Atomic Spectrometry Update- Industrial Analysis Metals Chemicals and Advanced Materials Atomic Spectrometry Update JOHN MARSHALL* AND JOHN CARROLL ICI Wilton Research Centre P.O. Box 90 Middlesbrough Cleveland UK TS90 8JE JAMES S . CRIGHTON BP Research Centre Chertsey Road Sunbury on Thames Middlesex UK TW16 7LN SUMMARY OF CONTENTS 1. Metals 1.1. Ferrous Metals and Alloys 1.2. Non-ferrous Metals and Alloys Table 1. Summary of Analyses of Metals 2. Chemicals 2.1. Petroleum and Petroleum Products 2.1.1. Crude oil and fractions 2.1.2. Lubricating oils 2.2. Organic Chemicals and Solvents 2.2.1. Chemicals 2.2.2. Solvents 2.3. Catalysts 2.4. Inorganic Chemicals and Acids 2.5. Nuclear Materials Table 2. Summary of the Analyses of Chemicals 3. Advanced Materials 3.1. Polymeric Materials and Composites 3.2.Semiconductor Materials 3.2.1. Silicon-based materials 3.2.2. Gallium arsenide-based materials 3.2.3. Indium phosphide-based materials 3.3. Glasses Ceramics and Refractories 3.3.1. Glasses 3.3.2. Ceramics and refractories Table 3. Summary of Analyses of Advanced Materials This Atomic Spectrometry Update is the latest in an annual series appearing under the title of ‘Industrial Analysis’. The structure of the review is broadly the same as in previous years. It is evident from this year’s literature that atomic spectrometric techniques are now beginning to develop in areas beyond the traditional remit of elemental compositional analysis. The instrumentation and methodology is now available to solve many of the most difficult problems in quantitative analysis albeit at a substantial cost (e.g.magnetic sector MS instrumentation). Consequently much of the research effort reported has gone into either improving the limitations of particular instrument types or to broaden the application horizons of existing techniques. In the case of the former methods for preconcentration of analytes and separation or removal of matrix components using column chromatography or extraction techniques predominate particularly in the analysis of metals nuclear materials and refractories. The improvements in sensitivity and freedom from chemical and spectral interferences which this type of approach confers can be applied to most of the spectroscopies of relevance with some benefit. In ICP-MS the use of such * Review Co-ordinator to whom correspondence should be addressed.techniques in conjunction with isotope dilution methodology has been successful in normalizing recoveries and in improving accuracy and precision. The now familiar and increasingly popular sample pretreatments involving HPLC- and GC-coupled techniques with plasma spectometers for speciation are of course related to the ion exchange/chelation resin separation methods but add value in providing molecule- and ion-specific information. However the multi-element capability of ICP-MS and ICP-AES in chromatographic speciation applications is hardly used at all perhaps indicating a limitation in current thinking. New frontiers are opening up in the use of GPC and HLPC for molecular mass characterization via elemental detection and in the notion of the combination of MS with soft plasma ionization (e.g.ICP or GD) to obtain molecular information in addition to elemental composition. The advent of electrospray MS is also of great interest in the identification of the valence state and even complexes present in solution and it may be that the classic separation between inorganic and organic spectroscopic techniques is coming to an end. The direct analysis of solids remains a subject of much activity and the ultimate goal of quantitative two- and three-dimensional compositional mapping by lateral and depth profiling gets a little closer each year via techniques such as GD and laser sampling for AES and MS and non-destructively by SIMS and X-ray microfluorescence. Total-reflection XRF too is clearly becoming a powerful tool for the surface characterization of semiconductors and advances in optics and detector technologies have increased the range of conventional XRF in light element detection of relevance in this area.It is often difficult to see the major advances in a given field because of the experience of daily contact with the subject. However after 10 years of Atomic Spectometry Updates it is gratifying to look back and see so many of the ideas which were being formulated a decade ago find their way into routine industrial application. This reviewer looks forward to the next decade with enthusiasm! 1. METALS This section of the review covers the analysis of ferrous non- ferrous metals and their alloys by analytical atomic spec- trometry.A summary of the analytical methods reported for metals in the year under review is given in Table 1. 1.1. Ferrous Metals and Alloys Inductively coupled plasma mass spectrometry is a technique which is being employed increasingly within the metals indus- try. The trend of recent years has continued in the period under review with a further increase in the number of abstracts received concerning the use of ICP-MS in application to the analysis of ferrous metals and alloys. Interest has focused on methods that limit the total amount of dissolved solids intro- duced to the plasma. High levels of dissolved solids have been Journal of Analytical Atomic Spectrometry December 1995 VoZ. 10 359RTable 1 SUMMARY OF THE ANALYSES OF METALS ~ Reference 9413076 9511964 Technique; atomization; analyte form* Element Ag Ag Matrix Sample treatmentfcomments AE;ICP;L AA;F;L Copper metal Placer Au Sample dissolved in aqua regia and silver was precipitated as the chloride and separated from the gold.The precipitate was dissolved in 5% hot thiourea solution. Determination of soluble and insoluble A1 for eight reference materials and comparison made with electrochemical methods. Anode dissolved in HNO,. Ascorbic acid employed as matrix modifier; standard addition calibration. Sample dissolved in HC1. One-step microwave digestion procedure. Method gave good agreement when applied to reference materials. Comparison of fire assay with AAS and ICP-OES. Sample solution (25 ml) mixed with 25 ml 0.1% NaCN and extracted into diisobutyl ketone.The resulting solution was centrifuged at 2000 rpm for 15 min. The organic layer was dried in a crucible and the residue dissolved in 6 ml HC1-2 ml HNO + 25 ml H,O. Batch hydride generation; slotted quartz tube employed to give three-fold increase in sensitivity. Sample (1-2 g) t 15 ml HNO placed in PTFE sealed vessels and placed in an ethylene glycol bath at 140°C for 1 11. Spectral interferences by excited state lead absorption lines were observed on both primary As lines (193.696 nm 197.197 nm). These interferences were eliminated by temperature programming and temporal resolution. FIA-ion exchange used to remove the iron matrix Generation of methyl borate in concentrated H2S04 FIA sample introduction; five-fold improvements in Modifier employed comprising of nickel and and H,PO media + methanol LOD zirconium salts.Graphite tube treated with zirconium solution. drops of HF. Digest treated with 5-8 ml of HCIO and heated to fuming and the residue dissolved in Sample (0.1 g) digested with 20 ml HN03 + a few K O . A review with references on the development of methods for the determination of Bi by AAS AES and electrochemistry. in sensitivity over conventional nebulization. Sample chip (2 g) decomposed with 55 ml(l+9) HF+a few drops of HNO,. This solution was transferred to an MCI GEL C K cation-exchange column. The Cd was then eluted using 50 ml (1 + 22) HC1. The eluate was evaporated to dryness and the residue dissolved in HNO,. The sample was dissolved in aqua regia and filtered. The filter paper was ashed and the ash fused with a flux of Na20-NazC0 and the melt dissolved in HC1.filtered. The residue was ignited in a Pt crucible (800 "C) mixed with HF-HNO evaporated to dryness fused with KHSO dissolved in HCl and combined with the original filtrate. The method was applicable to steel and iron samples containing 0.002-2% Cr. About 0.25 g of sample was dissolved in 10 ml aqua regia and the cooled solution mixed with 10 ml of ethanol. in MIBK and re-extracted in H,O matrix as basic bismuth nitrate. ETV sample introduction gave twenty-fold increase - Sample ( 1 g) was dissolved in HCl-HNO and The sample was dissolved in HCl-HNO extracted NH,OH neutralization method used to remove the Study of A1 interference effects. A1 Steel A&-$ 95/44 AA;ETA;L 951215 A1 Zinc anode A1 A1 High-purity tin Steels and iron ores AA;ETA;L AE;ICP;L 9512393 95/28 15 Gold metal Raw materials and waste products AA or AE;ICP;L AA or AEF or ETA or ICPL 95/21 951910 Au Au Steel and geological samples AA;HG,L 9512248 9512221 As As High-purity lead metal and AAS;ETA;L alloys B B Steel Steel AE;ICP;L AE;ICP;G 94fC3380 951160 B Steel MS;ICP;L 95fC49 1 Iron and nickel-based alloys AA;ETA;L B 9511877 Ba Aluminium alloys AA;F;L 951866 Bi Metals and alloys AA or AE;-;- 9413066 Bi Iron and steel samples Nickel-based alloys Zirconium alloys 9512583 AA;FL AA;ETA;L Bi Cd 9512865 951296 Cr Cr Steel Iron and steel AE;ICP;L AA,F;L 951865 9512806 Stainless steel AA;F;L c u 95/84 Fe Li Mg High-purity aluminium MS;ICP;L AA;F;L AA;F;L 95/1495 95/96 951292 Bismuth Aluminium and aluminium alloys 360R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 1 (continued) Technique; atomization; analyte form* Element Matrix Reference Sample treatmentlcomments Mg Zirconium and zirconium alloys AA;F;L Sample was dissolved in HF and boric acid used to react with excess HF. Method applies to 0.0001-0.002% Mg Sample (1 g) was dissolved in HCl oxidized with HNO evaporated to dryness and heated at 200°C for 5 min-the residue was dissolved in HCl diluted in H20 and filtered. As for Ca Direct analysis of the metal. Indirect method by determination of Na following ion exchange Powdered sample dissolved in aqua regia Direct analysis FIA-cation exchange used to remove the copper matrix The sample was dissolved in 4-5 ml of aqua regia. Sodium tartrate (10 ml) was added as a masking agent for antimony; Zeeman effect background correction was used Sample dissolved in mixture of HC1-HNO (4 + 1 Approximately 2 mg of sample was dissolved in a mixture of 10 ml HC1-3 ml HN03-5 ml H20.A slotted-tube atom trap was used to increase sensitivity. The sample was digested in a mixture of dilute HNO and HC1 and treated with HClO,; after reduction in volume and dilution ascorbic acid and HC1 was added and the solution filtered; the precipitate was washed with water and re-digested in a mixture of HNO and HClO heated until fumeless and finally boiled with a mixture of vlv) HCl-HNO,-H,O (3 + 1 + 3). Study of spectral interferences due to tungsten Steel chips (500 mg) were treated with 50% HNO - with microwave heating (120 W for 1 min 300 W 2 min and 600 W for 1 min) 9512366 9512807 9511206 9511014 951944 94/3078 94/3312 941C3398 94lC3396 95/242 9512501 Mg Iron and steel AAF;L Mg Manganese bronze Mn Steel Nb Steel AA;F;L AE;GD,S AA,F;L AEICPL AEGD;S AE;ICP;L AA;ETA;L Ni S tee1 P Nickel electrode coatings P Copper alloys Pb High lead-antimony regulus Sb Nickel alloys Sb Copper alloys A A;ETA; L AAF;L Se Steellheat resistant alloys AE;ICPL 9512513 Si Si Si Tungsten thread Si-Ni alloys Steel AE;ICPL AE;ICP;L MS;ICP;L 94/C3 3 8 1 9511950 9512542 9413336 9512502 Sn Sn Copper alloys Copper alloys AA;HGL AA;HG;L Sample (0.1-0.2 g) dissolved in a mixture of 5 ml HC1-2.5 ml HN03 and on cooling diluted to 100 ml with H20.This solution ( 3 ml) was mixed with 1 ml of 1% ethanolic 1,lO-phenanthroline to control interference from Ni and Cu.A 3 ml amount of 2% NaBH was then added to produce the hydride. A slotted-tube atom trap was used to increase sensitivity. Ta extracted as a fluoride complex in MIBK. Ta Ta T1 V V Titanium alloys Titanium-tantalum alloys Nickel alloys Nickel alloys Steel AA;F;L AA,ETA;L AA;F;L AE;ICP;L XRF;-;L 951172 9512239 951327 951851 951866 Microwave heating used in digestion procedure BS standard 7455 part 9 1994 The sample was dissolved in aqua regia; pg g-' levels determined. - Australian Standard method AS/NZS 1050.38 1994 Powdered sample was dissolved in aqua regia. The solution was filtered the paper ashed and the residue fused with Na202-Na2C0 and the melt dissolved in HCl. Development of standard reference material; using ICP-MS ICP-AES and ETAAS for certification.V V Zr Steel Iron and steel Alloys AA;FL AA;F;L AE;ICPL 9511 925 9512804 9413077 Various Gold metal AA AE or MS;ETA or 1CP;L AE;ICP;L 95/18 Various Platinum palladium and rhodium materials and solutions Various Gold metal Comparison of traditional wet chemical methods with ICP-OES 95/19 AA or AE;F or ICP-;L AE;ICP;L Comparison of fire assay with AAS and ICP-OES 95/21 Various (6) Copper metal Sample ( 5 g) was dissolved in 10 ml of aqua regia. Then 5 ml of 4 mg ml-' In"' + 10 g of ammonium nitrate were added. The solution was boiled filtered and the filtrate discarded. The precipitate 95/34 Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 361 RTable 1 (continued) Technique; atomization; Element Matrix analyte form* Sample treatment/comments Reference was washed with 10% ammonium nitrate and dissolved in 10 ml of aqua regia.Y (100 pg m1-I) was used as an internal standard. An ultrasonic nebulizer was used for introduction of the solution to the plasma. A computer program based on a model was used to correct for absorption enhancement and spectral interferences. pressure asher pressurized microwave decomposition device) were used to speed up sample preparation. Sample loss and contamination were reduced using these approaches. Preconcentration and extraction with 8-quinolinol solution in MIBK at pH 9.2 A review with 48 refs. on methods for the determination of impurities silver metal and alloys A review with 40 refs. on methods for the analysis of iron A review with 24 refs. comparing methods of analysis Investigation of matrix effects due to dissolution media.Microwave digestion employed for sample preparation. 1 7 1 0 ~ injection sample introduction. Elemental concmtrations used to establish origin of cartridge cases Separation of palladium and silver by coprecipitation with Y(OH) and precipitation of silver chloride Relative sensitivity factors for the elements of interest were determined by doping platinum samples with these impurities over a wide concentration range. determination of number of steel and nickel alloys. Improved precision reported with the FI method. Comparison of tabulated techniques by three laboratories. Indirect method based on the interferences of PO:- and Si02- on Ca.Partial least squares used for data analysis; the method allows the simultaneous determination of P and Si. Pressurized sample preparation devices (high Comparison of ETAAS and FIAAS for the Direct analysis of solid using laser ablation Molecular ion interferences and methods to overcome them are discussed The sample was dissolved in HNO and the solution evaporated to dryness. Impurity elements were extracted using an ethanolic solvent. Samples were dissolved in HCI-HNO solution. Impurity elements were coprecipitated with lanthanum hydroxide in ammonium hydroxide at pH 10 and separated from the nickel matrix. Depth profiling of brass coatings Sample (0.005-0.01 g) was dissolved in 0.5 ml of HCI-HNO (3:l) and evaporated to dryness and the residue wiis then dissolved in H,O.Sample (1 g) was dissolved in HNO,. A review with 34 refs. Nd:YAG laser (1064 nm) was used to ablate the samples; a solid state detector coupled with a high-resolution echelle spectrometer was employed for measurements. Good agreement was obtained with certified values for the analysis of reference materials. Investigation of spectral interferences in the analysis of steels sampled using laser ablation. Sample preparation were methods outlined optimum instrumental parameters tabulated and the effect of spectral interferences discussed. Sample (0.1 g) was treated with 5 ml of HCl and 5 ml of HNO in a double-wall microwave vessel. The solution was microwaved at 25 psi for 30 min. Then 1 ml of KCl (191 g 1-I) was added and the solution allowed to cool diluted to 50 ml and allowed to stand for 1 h.XRF;-;S AE;ICP;L 95/74 951140 Various (12) Steels Various Steel alloys A A;ETA;L Various (3) Titanium metal 951178 951239 Various Silver and silver alloys AA or AE;ICP;L AA or AE;ETA or ICPL MS;ICP;L AA;ETA;L Various (33) High-purity Fe 951267 Various Clean steels Various Zirconium 951268 951281 Various (6) Steel Various (3) Firearm cartridge case MS;ICP;L 951297 AA;ETA;L 951340 Various (22) Palladium-silver alloys Various Platinum powder AE;ICP;L MS;GD;S 951400 951535 Various (3) Steels and nickel alloys AA;ETA;L 951914 Various (33) Ultra-high-purity Iron Various (2) Manganese bronze AE or MS;ICP;L 951998 9511206 AA;F;L Various Gold and silver materials Various (4) Steel MS;ICP;S MS;GD;S 9511372 9511462 Various (4) High-purity lead AA;ETA;L 9511 888 Various (12) Lead-tin solder Various (7) High-purity nickel AE;ICP;L AE;ICPL 9511933 9511948 Various Brass-coated steel Various Nickel-based alloys MS;GD;S AA;ETA;L 9511952 9512183 Various (13) Iron and Steel Various Non-ferrous Metals Various (9) Steel AA;ETA;L AE;ICP;L AE;ICP;S 9512334 9512367 9512506 Various Steel Various High-purity noble metals MS;ICP;S MS;ICP;L 9512584 9 5/25 9 7 Various (4) Nickel alloy AA;F;L 9512830 362 R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 1 (continued) Element Various Various (2) Various (28) Various ( 18) Various (15) Various (3) Matrix Technique; atomization; analyte form* Low-alloy Steels AE;ICP or spark;L Copper metal steel AA;HG;L or S High-purity gold AE;ICP;L Zirconium alloys AE;ICP;L Unalloyed steel samples MS;ICP;L Microalloyed steels MS;ICP;L Reference Sample treatment/comments Multivariate calibration methods assessed ( principal component analysis partial least squares) FI employed for sample introduction.L-Cysteine used as reducing and releasing agent. The gold matrix was extracted with ether and the ether residue dissolved in HNO,. Study of spectral interferences due to the zirconium matrix. Flow injection sample introduction compared to conventional nebulization. Choice of internal standards to compensate for matrix interferences investigated. Flow injection sample introduction following sample dissolution in HNO with microwave heating 9512850 9513003 95/3011 9513025 9513056 9513062 *Hy indicates hydride generation and S L G and S1 signify solid liquid gaseous or slurry sample introduction respectively.Other abbreviations are listed elsewhere. shown to cause suppression of the analyte signal and drift problems owing to deposition of material on both the sample and skimmer cones. The use of F.I. as a means of sample conditioning both for analyte preconcentration and matrix removal has been widely applied in both FAAS and ICP-OES since the introduction of the technique in the 1970s. However the bulk of these applications were driven by the sensitivity limitations of the techniques in question and focused primarily on single-element preconcentration. The superior sensitivity and multi-element coverage provided by ICP-MS means that the majority of applications do not require any preconcen- tration and research has therefore centred on methods for matrix elimination.Thus FI sample introduction combined with microwave sample digestion has been applied to the determination of 15 trace elements in unalloyed steels (95/3056). Improved detection limits in the ng g-' range were reported. Flow injection and ICP operating parameters were optimized and suitable internal standards chosen to eliminate matrix effects due to iron and to compensate for ion signal instability. The method was applied to the analysis of two pure iron reference materials (CRM 097 and NIST 367). The relative standard deviation for all analytes studied was <3% for concentrations above 1 pg g-'. A similar approach has been applied to the determination of Bi Sb Se Sn and Te in steel (95/297).Flow injection parameters such as carrier flow rate and sample loop volume were optimized with respect to sensitivity and precision. Good agreement was obtained when the method was employed for the analysis of standard reference materials. The FI-ICP-MS technique has also been applied to the determination of B in steels (95/C491). The use of electro- thermal vaporization in the determination of Bi in iron and steel samples by ICP-MS has also been investigated (95/2583). Detection limits obtained were improved by a factor of fifty compared to those achieved using conventional nebulization. An investigation of instrumental parameters affecting the direct semiquantitative analysis of steels using IR laser ablation ICP-MS was undertaken (95/2571).Under some ablation conditions non-representative subsampling occurred for samples containing components with low melting- or boiling- points. This effect was reduced by minimizing the spatial overlap of laser pulses on the sample surface. The use of a high-resolution MS system with both ICP and GD has been described and applied to the analysis of steels (95/C2043). Continuing the theme of direct analysis a number of abstracts have been received concerning the development of novel glow discharge sources for the analysis of steels. A modified Grimm discharge has been designed to operate with a TMOlO microwave resonator (94/C3393). The modified discharge provided greater excitation and as a result detection limits obtained for the analysis of steel samples were reported in the sub-pg g-' range.The characteristics of an rf powered glow discharge for AE measurements have been described (95/C377). Claims were made that this approach assessed in terms of detection limit precision accuracy and sampling diversity was a viable alternative to arc and spark AES. Relative sensitivity factors (RSFs) have been determined for the analysis of alloying elements in steel by glow discharge MS (95/1309). The factors were determined empirically by examination of 30 steel samples selected from five Japanese reference standards [Japanese reference standards of Iron and Steel (JSS)]. Good agreement was obtained with the certified values when the factors were used in the analysis of a heat resistant superalloy JSS CRM-680-3. A technique for the simultaneous multi-element determi- nation of trace elements in steel has been reported (94/2999).The system employed laser ablation as a means of directly volatilizing the sample into a microwave-induced plasma. Optical fibres were used to link the echelle spectrometer and a gateable optical multichannel detector head. This configur- ation allowed simultaneous determination of up to 10 elements using single laser shots. A spark ablation unit has been coupled to an argon MIP system and used for the direct analysis of solid samples (95/330). Particles of the sample were generated by the spark and swept into the plasma. This system was employed for the analysis of low-alloy steels and aluminium alloy standard reference materials. Limits of detection for the analyte elements of interest were at the 10 pg g-' level and were comparable to those obtained using a spark-coupled argon ICP system.However the precision values obtained were in the range 3-11% which were 2-3 times higher than could be achieved using the ICP-based system. Continuous direct measurements of the 11 air-toxic metals regulated by the Clean Air Act (As Be Cd Cr Co Pb Hg Mn Ni Sb and Se) has been achieved by the use of laser spark spectroscopy (more commonly known as laser-induced breakdown spec- troscopy LIBS). In this technique a pulsed laser source was used to rapidly heat a particle which in turn produced a laser spark (plasma). Optical emission from the spark was spatially resolved and the corresponding emission spectra used to identify the constituent elements of the particle and quantify the abundance of the measured species (95/C745).In an alternative approach to a similar problem ICP-OES has been employed for the real-time monitoring of effluent from an incinerator plant. The instrument was monitored to permit the Journal of Analytical Atomic Spectrometry December 1995 VoE. 10 363Rperiodic introduction of an isokinetically-sampled air stream. Measurements obtained with the system agreed within a factor of 2-3 to those obtained by conventional sampling methods Inductively coupled plasma emission spectrometry continues to be widely applied in the ferrous metals industry and a comprehensive survey of the methods reported is provided in Table 1. A number of novel applications which may be of particular interest were received during this review period.An ICP emission spectrometer with a high-resolution echelle optical system has been coupled with a laser vaporization sampler and applied to the analysis of steel and soil samples (95/2506). The determination of C Cr Cu Mn Ni P S Si and V in certified steel samples was carried out using iron as an internal standard. Calibration functions were reported to be linear for all elements studied with the exception of C. Good agreement was obtained with reference steels data with RSDs of the order of 7%. A method had been developed for the determination of B in steel by ICP-OES using chemical vapour generation of B (95/160). The procedure was based upon the discontinuous generation of methyl borate in a concentrated sulfuric and phosphoric acid medium after the injection of 45 pl of methanol in 20 pl of sample.The methyl borate vapour and excess methanol was introduced to the plasma without disturbing the discharge. The iron matrix was not found to cause any interference problems. The reproduc- ibility of the method was reported as 1.9% relative for 20 pg ml-' B. An absolute detection limit of 20 ng of total B was achieved using a sample volume of 20pl. This method was claimed to greatly simplify this determination in compari- son with established methodologies. Spectral interference of iron on the most sensitive B lines at 249.78 nm and 249.65 nm is known to cause problems in the analysis of steels by ICP-AES. A method based on the use of a matrix removal approach has been proposed to overcome this difficulty (94/C3380).An FI procedure employing a cationic exchange resin was used to remove the Fe matrix on-line prior to ICP- AES measurement. The effect of sample solution pH the size of the ion-exchange column and the optimization of elution conditions were studied. Multivariate calibration methods have been applied to the determination of Cr Mn and Ni in low- alloy steels using both ICP-AES and spark AES (95/2850). Partial least squares (PLS) and principal component analysis procedures were examined for the improvement of analytical parameters such as sensitivity and detection limit and the results compared with those obtained by univariate optimiz- ation. The use of distributed lines in multisignal calibration was also discussed.As with previous reviews numerous abstracts were received outlining methodologies for the analysis of ferrous metals and their alloys by the more mature analytical techniques such as XRF FAAS and ETAAS. Many of these papers concerned the development of sample preparation protocols which while not entirely original in concept may be of practical benefit as a reference source. Details of these methods are conveniently summarized in Table 1. (95/C744). 1.2. Non-ferrous Metals and Alloys A significant number of abstracts describing developments in the use of glow discharges for both AE and MS for the analysis of non-ferrous metals and alloys have been received during the current review period. This research activity is indicative of the increasing practical usage of this technology in metals analysis and the need for improved sources in order to meet ever more exacting analytical requirements.The application of a magnetic field to a Grimm glow discharge lamp as a means of improving its performance has been reported (95/3063). An Nd-Fe-B magnet was placed behind samples of Cu and Cu-Ni-Fe alloy. Sputtering rates in argon (at 1000 V 4 Torr) were reported to increase from 100 to 200pg min-l for Cu owing to the influence of the magnetic field. An increase in noise was observed when the magnetic field was applied. The Cu I emission at 282.4nm increased when the magnetic field was applied in line with the increased sputter rate. However for Cu I at 324.7 nm for the Cu sample and for Cr") in the alloy containing 0.06% Cr a reduction in the emission inten- sity was observed in the presence of the magnetic field. This was attributed to self-absorption effects.In another study published by the same research group a side-on viewed source was developed to examine special emission features of an rf-powered glow discharge (95/2181). Spatial profiles of Ar emission at 420nm Cu emission at 324nm and OH band emission were collected with an imaging spectrometer. The source was operated over a pressure range of 0.1-1 Torr at rf power levels of 20-50 W. A further modification to the source was made by placing two magnets to create a transverse field in the region above the cathode surface. Effects on the applied magnetic field on the voltage characteristics of the source the sputtering ra,te and the spatial emission features of the source were investigated.A systematic investigation of spectral line selection and an evaluation of the analytical performance of an rf glow discharge source for the AE analysis of copper and aluminium and alloys has been reported (95/2997). Line selec- tion was based on S/Bs for bulk metals and S/Ns for trace analysis. The analytical lines selected on the basis of these criteria were used to evaluate analytical figures of merit. A review (39 refs.) outlining developments in dc glow discharge spectrometry for depth profile analysis has published (95/1018). Quantitative glow discharge AES was described in detail and current applications of GDMS to quantitative depth profile analysis was covered briefly. Glow discharge mass spectrometry has been applied to depth profiling of frictional brass coated steel (95/19S2).A linear combination of relative sensitivity factors and sputter rates in pure iron and brass matrices was used to quantify continuously varying concentrations of Cu Fe and Zn in the coated layers. A technique for the analysis of solid samples in air at atmospheric pressure has been described (95/2197). A xenon chloride laser was used to ablate and excite the sample and the resulting AE signal was registered using an optical spec- trometer. Optimization experiments carried out using the system were described. A strong dependence was observed between the intensity of the generated plasma and the number of laser shots delivered to a specific location. In order to achieve good control of the ablation process using this system it was necessary to establish the exact number of shots delivered before and during data acquisition.Time-resolved measure- ments were performed in the 1-4 ps range to eliminate back- ground emission and to avoid data capture during plasma collapse. Internal standardization was employed to normalize the signal response. Analytical performance was reported for the determination of Mg in aluminium alloys. Inductively coupled plasma atomic emission spectrometry remains the most popular technique for the analysis of non- ferrous metals on the basis of abstracts received. The influence of matrix spectral interferences in the determination of trace impurities (1 5 elements) in zirconium metal by ICP-OES has been the subject of investigation (94/3025). Information was given on spectral line selection to avoid overlaps with lines due to the Zr matrix.In cases where this was not possible line interference corrections were utilized. The proposed analytical protocol was tested using the analysis of NIST standard reference materials and the results obtained were in good agreement with the certified values. Flow injection sample pretreatment has been employed for matrix elimination in the analysis of E' in copper-based alloys by ICP-OES. The severe spectral overlap of the copper 213.6 nm and 214.9 nm lines on 364 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10the most sensitive P wavelengths (213.62 nm and 214.91 nm) present difficulties when attempting this analysis in an air path spectrometer.The copper matrix was retained on a cationic ion exchange column thus allowing the analyte to be separated and introduced directly to the plasma. Details on optimization of separation parameters were given. A method for the direct analysis of aluminium alloys by ICP-OES using direct sample insertion has been described (94/3241). The use of a mixed gas oxygen-argon plasma was required for the successful appli- cation of this method. Calibration curves were linear over three to four orders of magnitude and the detection limits were in the range of tens of picograms. No sample pretreatment was necessary using the method. Finally a review (34 refs.) has been published on the development in methodology and instrumentation for the analysis of non-ferrous metals by ICP- OES( 95/2367). Applications areas covered by the review included light metals heavy metals refractory metals and noble metals.Despite the dominance of ICP-OES and the emergence of ICP-MS and GDMS in the metals industry both FAAS and ETAAS are significantly represented in the applications base covered by this review. This perhaps reflects the economics of the situation in that not all laboratories are in the fortunate position to acquire instrumentation at the top end of the market and as such must rely on what resources are available. However the wide range of sample preparation methodologies and inventive front-end chemistries used to improve sensitivity and detection limits particularly in FAAS are testimony to the skills and ingenuity of the analytical community.Details of improvements in sample preparation relating to these tech- niques are given mainly in Table 1. A series of papers have been published describing the use of FAAS for the determi- nation of Sn (94/3336 95/2502) and Sb (95/2501) in copper alloys. A slotted tube atom trap (STAT) was employed to increase sensitivity in these methods. Results for the analysis of standard reference material were reported in each case. A method has been described for the analysis of trace amounts of A1 in high purity tin by ETAAS (95/2393). The sample was dissolved in hydrochloric acid and no modifier was employed providing a simple and rapid method of analysis. Studies were also carried out on the mechanism of interaction of A1 with the tin matrix during the furnace sample pretreatment.It was reported that in the drying stage A1 trichloride and tin@) chloride were converted into A1 hydroxide and tin hydroxy- chloride respectively. During the ashing stage A1 trichloride was converted to A1 oxide which was not volatile at that temperature. In contrast significant amounts of tin hydroxy- chloride were lost by evaporation and a small amount was converted to tin oxide. It was found that the latter did not interfere in the determination of Al. The method was used to determine A1 levels in the 0.1-6 ppm range and good agreement was achieved for the analysis of certified reference materials. The use of ETAAS for the analysis of Bi and Pb in nickel- based alloys has been reported (95/2183). In the case of Pb the background absorption arising from the presence of the alloy matrix were successfully compensated for by the deu- terium background correction system and the use of chemical modifiers were not necessary.For Bi it was reported that the presence of matrix modifiers (such as palladium or EDTA) could not prevent overload of the background correction system at the analyte wavelength. To resolve this problem Bi was separated from the matrix by coprecipitation by the addition of ammonium hydroxide solution. Using this approach Bi could be determined directly with no interference due to background absorption and scatter from the nickel matrix. The method was validated using standard reference materials. Nickel-based alloys have also been analysed by ETAAS for trace amounts of T1 (95/327).The alloy was dissolved using a microwave digestion procedure involving treatment with sulfuric hydrofluoric and nitric acids. An alternative hot-plate digestion procedure using a mixture of sulfuric and hydroffuoric acids and hydrogen peroxide was employed for comparison. Ascorbic acid was used as a modifier for the ETA-procedure. Comparable results were obtained for both digestion procedures. The use of platform atomization was found to improve the absorbance signal and the precision of the measurement. The method gave good agreement in with certified values for nickel-based alloy reference materials. A review (20 refs.) on ultratrace analysis by ETAAS may be of some interest in this context (95/2320). The categories of application surveyed by the review were the analysis of nickel- based alloys and steels. A review (73 refs.) has been published on applications of XRF in the aluminium industry (95/1063).The areas covered were aluminium minerals (bauxite) reduction cell electrolyte and aluminium alloys. Detailed lists of reference materials for nickel and nickel alloys (95/2162) cobalt and zirconium alloys (95/2153) and lead and tin alloys( 95/2 152) have also been published during the period covered by this Update. As with the other areas of metals characterization the use of ICP-MS for the analysis ofprecious metals has become more popular and an increase in the number of applications reported is noticeable. The direct determination of trace metals in gold and silver materials by laser ablation ICP-MS has been described (95/1372).Trace metals were determined in high- purity gold high-purity silver and 14 carat gold-silver alloys. An Nd:YAG laser was used to evaporate solid samples for precious metals into the plasma. In many cases accurate analysis of trace elements by this approach requires the use of matrix-matched standards. Data analysis and a study of crater size in this application indicated that approximately the same amount of material was ablated for both gold and silver samples. For the elements studied (Bi Cu Fe Pd Pt and Zn) no difference was observed when the instrument was calibrated using gold or silver materials. As a result this permitted all of the sample types to be determined using only one set of reference materials as calibration standards. The direct determi- nation of trace elements in pure copper gold and silver by spark ablation plasma optical emission and mass spectrometry was described (94/C3373).The spark emission chamber was used with both the optical emission and the mass spectrometer channels available with this instrument. The operating con- ditions such as spark cycle and power ICP operating con- ditions and sampling position were optimized for MS. The internal standard was selected from the MS polyatomic ions such as CuAr AgAr or alternatively the emission line from of the matrix element was employed. For detection by mass spectrometry detection limits below 10 ng g-' were claimed for most elements. The study compared this approach with that of using laser ablation sampling and concluded the use of the spark system was a viable alternative for conducting samples. The development of standard reference materials for use in the analysis of fine gold has also been reported (95/18).A review (48 refs.) on the analysis of silver and gold alloys by atomic spectrometric techniques has also been published ( 9 5/239). A method for the direct analysis of platinum powder by GDMS has been reported (95/535). Relative sensitivity factors were determined for the analyte elements of interest. This was achieved by analysis of platinum samples doped with analyte elements over a wide range of concentrations. These RSFs were then used in the direct analysis of a previously quantified platinum powder. Results obtained using GDMS showed accuracy values in the range of 10-15% and repeatability values of 5-10%.The analytical figures of merit obtained for GDMS were compared to the other spectroscopic techniques employed for the analysis of platinum. The ease of sample preparation sensitivity and speed of analysis were claimed to Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 365 Rmake this technique more attractive than competitive approaches. In one of the key areas of interest in this field ICP-OES has been benchmarked against classical wet chemical procedures for the precise determination of precious metals (95/19). Methodologies based on ICP-OES were developed to achieve results of gravimetric quality. Results obtained showed excellent agreement for a number of samples types such as platinum catalyst rhodium scrap platinum-palladium refining solutions and automotive materials.2. CHEMICALS 2.1. Petroleum and Petroleum Products Most of the work carried out during the review period has been concerned either with providing more information to aid in the search for oil or with the growing concern over environ- mental impact (particularly in the burning of fossil fuels) although determination of additive and wear metals in lubricat- ing oils continues to attract some attention. A summary of the literature received is given in Table 2. 2.1 .l. Crude oil and fractions Exploration geochemists have long relied on measurement of molecular biomarkers (usually obtained using GC-MS) for paleoenvironmental reconstructions estimation of source maturity and generation potential and for oil/source rock correlations.However an implicit assumption in most of this work is that all of the compounds measured originate from a related lipid pool. More recently attempts have been made to overcome this limitation by obtaining stable carbon isotopic composition for individual components/compounds using gas chromatography-isotope ratio mass spectrometry (GC-IRMS). During the review period a study of this type has been carried out (95/2424) for alkanes in oils and their associated asphaltene pyrolysate alkanes for seven crude oils sourced from different source rock types. Differences in 13C of up to 4% were observed between individual alkanes of the oil and asphaltene pyrolys- ates which the authors suggested could indicate that these originated from different sources.Bjoroy et al. (95/2423) have used a similar approach to study the C4-C20 fraction of North Sea oils and condensates. This appears to show that the oils/ condensates in the Central Grabben are not from a single source as had previously been proposed. The authors also showed that prolonged (48 h) storage at elevated temperatures (30 "C) did not significantly affect the carbon isotopic measure- ments. In order to obtain reliable indications of facies variation from this technique however it is necessary to correct for the effects of maturity since it has been shown that this can account for 50-90% of the observed isotopic variation (95/2425). In a study of the accuracy and precision of carbon isotopic analysis of individual n-alkanes using GC-IRMS it has been shown that in the absence of co-eluting peaks 13C results are generally correct to within 0.5% (95/2436).Furthermore it was shown that compound class separation using silica gel gravity liquid chromatography did not cause significant isotopic fraction- ation. Therefore it was concluded that differences of more than 0.5% in the I3C values of individual n-alkanes appeared to be significant even in the presence of background. GC-IRMS has also been applied to stable isotope nitrogen ratio measurements of natural gases (95/1401). Trace metals can also provide useful information which can aid in oil-source rock correlations. This approach has not been widely applied however partly owing to limited avail- ability of multi-element techniques with sufficient sensitivity but also owing to a general poor understanding of the complex interactions of trace metals in the oil with reservoir minerals formation waters formations through which the oil migrates and chemicals and equipment used during production and storage.Olsen et al. (95/1344 and 95/C2009) have shown that ICP-MS and INAA can provide complementary information which meets the analytical requirements for the above task and that this information can in some circumstances be used to distinguish oils from different oil fields and oil types. Similarly a Chinese study of over 200 samples of crude oil source rocks and oilfield water using synchrotron radiation XRF has shown that 30 elements could be determined down to ppm levels and that these could be used to classify types of crude oil and for source rock correlations (95/1725).However many more studies of this type will be required before the complex interactions are fully understood and trace element concentrations are adopted as a main-line technique in explo- ration geochemistry. Although ICP-MS analysis of crude oils can be carried out after direct dilution with hydrocarbon solvents this generally necessitates that the spray chamber is cooled to low tempera- ture and that oxygen is added to the plasma to prevent blockage of the sampling cone with carbon. Furthermore sensitivity is generally degraded and molecular ions from carbon and oxygen containing species cause severe inter- ferences on many isotopes. Many of these problems can be substantially reduced by introducing the sample in the form of a microemulsion. The latter approach has been applied to determination of Cd Co Cu Fe Pb and Zn in Saudi Arabian Crude Oils from four different fields representing heavy medium and light crudes (94/3148).Calibration was accomplished by standard additions using an oil-soluble multi- element standard. An alternative approach which can be used with both ICP-MS and ICP-AES is to desolvate the sample aerosol prior to introduction to the plasma. Botto (95/C558) has described use of an ultrasonic nebulizer with a microporous membrane desolvation system for introduction of volatile petroleum products into ICP-AES. The system achieved near complete removal of organic matrix from the sample aerosol prior to introduction into the ICP permitting use of a 'univer- sal' (solvent independent) calibration (using internal standard to compensate for differences in nebulization efficiency). The author predicted widespread application for analysis of light distillate feedstocks gasolines and high-purity solvents.However difficulties may be encountered if the analyte element itself is present in a volatile form. Another drawback with direct analysis of crude oil and related products after dilution with hydrocarbon standards is the requirement for costly organometallic solvents. A novel solution to this problem has been reported which involves coulometric preparation of reference solutions of Co Cu Ni V and Zn in organic solvents by anodic dissolution of the corresponding metals (95/2799).A somewhat simpler approach is to use mixed solvent systems which will dissolve petroleum products but which will also tolerate reasonable concentrations of water. It has been shown that a 1 + 4 mixture of 2,6-dimethyl- 4-heptanone (IDBK) and propan-2-01 can fulfill this role and can tolerate up to 30% water by volume (for incorporation of inorganic standard solutions). This solvent system has been used for FAAS and GFAAS determinations of Ni and V in crude oil and petroleum products using aqueous standard stock solutions (95/C553 and 95/C557) although FAAS deter- mination of V and GFAAS determination of Ni required the addition of matrix modifiers (cationic surfactant and 1500 pg g-l Pd respectively). Continuously tightening legislation on permitted levels of sulfur in fossil fuels has led to increasing interest in measure- ment of sulfur in crude oils refinery streams and finished products.There is therefore a growing need for standardized methods of analysis and for Standard Reference Materials (SRMs) to help ensure consistency of results between labora- tories. A significant contribution to the latter has been provided through determination of sulfur in 13 petroleum and 14 coal 366 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10Table 2 SUMMARY OF ANALYSES OF CHEMICALS Technique; atomization; analyte form* Element Matrix Sample treatment/comments Reference PETROLEUM AND PETROLEUM PRODUCTS- As Gasoline AA;ETA;L Samples pretreated with iodine to break down volatile organo-metallic complexes prior to simultaneous determination of both As and Pb using GFAAS equipped with dual galvanometer drive system to control rapidly alternating source and wavelength selection using AAS after combustion and hydride generation using sodium tetrahydroborate. (Limit of detection = 5 ng g-') Study of variation in isotopic composition of single components in C,-C fraction of North Sea oils and condensates using GC-isotope ratio MS.composition of crude oil alkanes and associated asphaltene pyrolysate alkanes using GC-isotope ratio MS. individual compounds in North Sea oils. Maturity found to account for 50-90% of observed variation but some source differences also apparent. Carbon isotopic analyses of individual n-alkanes extracted from marine particulate organic matter using GC-isotope ratio MS lubricating oil (up to 35%) surfactant (8-10% ethoxy nonylphenol 10 mol 1-') and water analysed directly by ICP-AES and gasoline by microemulsion nebulization ICP-MS.Detection limits were 0.015-0.17 pg g-' Cd Determination of cobalt naphthenate in gasoline by microemulsion nebulization FAAS. Identification and determination of five classes of Cu compounds formed by interaction between jet fuel and Cu in presence and absence of Du Pont metal deactivator using HPLC-FAAS (limits of detection approximately 10 ng g-'). Sample (1-3 g) diluted with petroleum solvent and Fe determined by FAAS using air-C2H2 flame at 248.3 nm. microemulsion nebulization FAAS (0-10 pg g-' Fe) 95/c5 59 Arsenic determined in thermally cracked gasoline Comparative study of stable carbon isotopic Study of effect of maturity on 13C/'*C ratios of Emulsion prepared by ultrasonic agitation of Cd determined in Saudi Arabian aviation fuel diesel Determination of ferrocene in gasoline by As for Ca.Determination of tricarbonyl-( 2-methyl- cyclopentadieny1)manganese and bis- (pentamethylcyclopentadieny1)manganese in gasoline using GC with a plasma emission detector at 403.45 nm. Detection limits were 62 and 69 pg s-' respectively. Nitrogen isotopic ratios measured using GC-MS. Standard deviations of f 0.5% possible using sample sizes as small as 10 nmol and with nitrogen concentrations down to 0.1% calcined at 550 "C. Resulting solid dissolved in 15 ml HCl (1 l) preconcentrated to 2 ml and then diluted to 25 ml in plastic vessel.Modification of IP288 method for direct determination of Ni and V after solvent dilution. Precision determined from round-robin study consisting of 54 European laboratories showed significant improvement over IP288. (Concentration range Samples diluted in DIBK-propan-2-01 ( 1 + 4) with standards prepared in the same mixture from aqueous inorganic solutions. Samples diluted in DIBK-propan-2-01 (1 + 4)with standards prepared in the same mixture from aqueous inorganic solutions. Matrix modifier ( loo/,) of 1500 pg g-' Pd or dodecylbenzenesulfonic acid required to obtain acceptable results for Ni. Sample (25 ml) burnt on electric heater and residue 1-70 pg.g-9 As Gasoline AA;F;L 9511087 C C Crude oils and condensates MS;-;L Crude oil MS;-;L 9512423 9512424 C North Sea Oils MS;-;L 9512425 C Ca n- Alkanes Lubricating oil MS;-;L AE;ICP;L 9512436 951912 Cd Petroleum products MS;ICP;L 9511308 Gasoline Jet fuel AA;F;L AA;F;L 951943 951102 c o c u Fe Lubricating oil AA;F;L 95/78 Fe Gasoline AA;F;L 95/28 3 7 Lubricating oil Gasoline AE;ICP;L AE;ICP;L 951912 9512857 Mg Mn N Na Ni Natural Gas Crude oil or diesel Fuel oil MS;-;L AA or AE;F;L AA;F;L 95/1401 9512546 9413 124 Ni Ni Crude oil and petroleum AA;F;L products 95/c 553 95/c557 Crude oil AA;ETA;L Journal of Analytical Atomic Spectrometry December 1995 Vol.10 367 RTable 2 (continued) Technique; atomization; analyte form* Sample treatmentlcomments Reference 9512176 94/c 3 40 5 9511 951213 95/c559 9511 308 9511345 9 511 68 5 95/c2915 951C2916 9 5/c 5 54 9413 124 9 5/25 53 95/c557 951912 9413 148 9413328 94/c3 40 1 94fC3444 Element 0 Pb Pb Pb Pb Pb S S S S Si V V V Zn Various (6) Various (5) Various (wear metals) Various Matrix Organic matter MS;-;L Revised method for oxygen isotope analysis of organic matter and water utilizing nickel pyrolysis bombs and simplified operating procedure which eliminates need for Ni powder catalyst or spark discharge chamber.Gasoline samples formed into microemulsions using sodium dodecyl sulfate butanol and water. Calibrated using aqueous standards Review (59 refs.) of application of GC coupled with atomic spectroscopic detectors for measurement of organolead compounds in water sediment and biological materials Method for determination of tetraethyllead and total lead based on conversion of tetraethyllead to inorganic lead using iodine monochloride As for arsenic As for Cd.Detection limits were 0.006-0.16 pg g-' Pb Total S measured in 13 petroleum and 14 coal SRMs by isotope dilution thermal ionisation MS. Total uncertainty (%YO confidence) approximately 0.5% for petroleum samples and 1-4% for coals. On-line sulfur analyser for measurement of S in process streams of naphtha kerosine and light and heavy oils (range 0.01-5% m/m S) Recent developments in EDXRF for improved precision in determination of sulfur in reformulated gasoline. Results compared favourably with WDXRF sulfur in petroleum products by WDXRF (US government required method for reformulated gasoline and diesel fuel). Determination of carry over of Si containing foam inhibitors and catalyst fines in refinery streams and products Discussion of ASTM D2622 standard test method for As for Ni.(Concentration range 2-180 pg g-') As for Ni but cationic surfactant matrix modifier required [Aliquat 336 and cetyl pyridinium chloride ( 1 % v/v) used]. As for Ni As for Ca. Sample mixed with tetralin Triton X-100 and water and vortexed to produce a microemulsion which was analysed directly (Cd Co Cu Fe Pb and Zn determined) Fundamental parameters methods applied to determination of Ba Ca Fe S and Zn at concentrations up to 1 mg g-' using WDXRF. Acid dissolution used for analysis of oils containing large particles (up to 88 pm) acidlmixed solvent dilution used for samples containing smaller particles (up to 10 pm) wavelengths down to 120 nm to be measured and rapid change in plasma conditions for optimal performance for alkali metals.Limit of detection for chlorine (134.7 nm) was 1 pg g-' (cf. > 1000 pg g-' for visible line) workstation capable of preparing used oil samples for ICP-AES analysis at rate of one sample every 78 s with dilution accuracy better than 0.5%. Ultrasonic nebulization with microporous membrane desolvation used for direct analysis of volatile petroleum products (e.g. solvents light distillates and gasolines). INAA and ICP-MS compared for analysis of crude oils fractions and source rock bitumens. Good agreement for some elements (e.g. As Fe Ni Se and V) but techniques complementary for others (e.g. B Be Cd and Br) New spectrometer described which dlows Description of bench-top automated robotics AA;F;L Gasoline Organolead compounds Various Gasoline AA;F;L AA,ETA;L MS;ICP;L Gasoline Petroleum products Fossil fuels MS;thermal ionization;L Refinery streams XRF;-;L Gasoline XRF-;L Fuels XRF;-;L Refinery streams and products AE;ICP;L Fuel oil Crude oil and petroleum products AA;F;L AA;F;L Crude oil Lubricating oil Crude oil AA;ETA;L AE;ICP;L MS;ICP;L Hydrocarbons XRF;-;L Aircraft oils (lubricating and hydraulic) AA;F;L Petroleum products AE;ICP;L Various Lubricating Oil (wear metals) AE;ICP;L 95/C556 9 5/C 5 5 8 Various Volatile petroleum products AE;ICP;L Various Crude oil and fractions MS;ICP;L and NAA 9511344 368 R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 2 (continued) Technique; atomization; analyte form* Element Matrix Various (5) Drilling fluids Sample treatmentlcomments Reference 9511590 9511619 9511725 9511786 95lC2009 951c2022 95/2308 XRF;-;slurry XRF used for determination of Ba C1 Cr K and S in drilling fluids containing solids suspended in liquid phase such as oil or brine.Samples mixed with binder powder to absorb oil create uniform particle structure and prevent problems with out-gassing of samples in X-ray beam. Synchrotron radiation XRF used to determine 30 trace elements in oil water and source rocks. Limits of detection in pg g-' range Major minor and trace components determined using PIXE RBS INAA ESCA ICP-AES NMR and ion chromatography. Intercomparison of ICP-MS and NAA results for 25 Exxon oil samples. Metals concentrations (e.g. Co Ni and V) allowed oils from different fields to be distinguished INAA used to measure 40 elements in solid fossil fuels (coal or oil shale) and their combustion products (slag ash from different aggregates and fly ash) Filter debris samples from helicopter gearboxes and aircraft engines analysed for 19 elements using INAA.Comparison with analysis of corresponding oil samples showed little useful wear information could be found in the oil of a finely filtered engine system. Method proposed for coulometric preparation of reference solutions of Co Cu Ni V and Zn in acetone-ethanol-xylene mixtures by anodic dissolution of the corresponding metal at specified current. oils. Overview of use of ICP-AES for analysis of engine Various Greases XRF;-;L Various Crude oil source rocks and oilfield water Various Brown coal and liquefaction products Various Crude oil XRF;-;L or S Various MS;ICP;L and NAA Various (40) Combustion products NAA;-;S Various Lubricating oil NAA;-;S Various ( 5 ) Petroleum and products AA;F;L 9512799 Various Lubricating Oil AE;ICP;L 95/28 13 ORGANIC CHEMICALS AND SOLVENTS- A1 Pharmaceutical infusion AE;ICP;L solutions 951328 Evaluation of seven emission lines of which only 167 nm and 396 nm gave detection limits below 5 ng ml-'.Former line gave the lowest detection limit but suffered interference for samples containing high iron or organic carbon whereas latter line suffered interference from high levels of calcium L-Cystein used in place of KI for reducing pentavalent to trivalent forms of metals at room temperature. Lower acid and reagent concentrations required than with KI and solutions stable for at least 1 week (cc 1 day for KI).Concentration range = 0.01 to 5 ng 1-l Sample (10 mg As) heated with H,SO,/ammonium sulfate/K,SO (10:2 1) for 4 h cooled and diluted (H,O) to 100 ml. 2.5 ml of resulting solution diluted to 100 ml with 1% H2S04 and then 1 ml mixed with 1 ml of 1% NiS04 and diluted to 50 ml with 1% H,SO Comparison of solvents for dissolution of drug substances for determination of boron using ICP-AES. Acetic acid best in terms of solubility wash out times and spectral band structure. Evaluation of low power (approximately 100 W) low pressure ICP-MS as an element specific detector for gas chromatography. Detection limits < 10 pg and linear range 2-3 orders Determination of volatile brominated hydrocarbons using one colour (260.634 nm) laser induced photofragmentation-xcitation.Detection based on resonance enhanced multi-photon ionisation gave best limits of detection (ppb) but only for low laser energies. As L-Cystein (reducing agent) AA;HG;L 9413002 As Chinese patent drugs A A; ETA;L 9511057 Pharmaceuticals AE;ICP;L 94fC3463 951527 95/22 1 1 B Br Br Halogenated GC effluents Brominated hydrocarbons MS;ICP;L AE;laser;G or AF;laser;G or LEI;G Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 369RTable 2 (continued) Technique; atomization; analyte form* Sample treatment/comments Reference 95/C620 Element Matrix C Organic compounds AE;ICP;L Measurement of total organic carbon in water samples by direct measurement of the carbon emission line after introducing samples into ICP using a direct injection nebulizer (DIN).Detection limit was 0.5 pg g-' but could be lower if background reduced Three MIP sources (Beenakker surfatron and torch) compared. Beenakker gave lowest detection limit (0.05 ng m1-I) and gave correct C:Cl ratios when amount of analyte was low. Torch gave superior element ratios when amount of analyte was high. Comparison of experimental and theoretically calculated high resolution X-ray emission spectra for methane and mono di tri and tetra- fluoromethane Study of peak splitting for high molecular mass polycyclic aromatic compounds in microwave plasma of GCI-MIP-AES. Addition of additional make-up gas shown to improve peak shapes ICP-AES nebulizer used to introduce samples to combustion total organic carbon (TOC) analyser. Signals more symmetric and noise reduced c$ conventional drip sample introduction Three digestion techniques compared.Best results obtained using autoclave digestion at 105 "C and 0.4 kg cm2 for 1 h. (Calibration linear up to 5 pg ml-'; limit of detection 0.8 pg 1-') Determination of Cd Cr and Pb in Pian Zihuang and Liuwei Dihuang Wan using GFAAS. (Calibration range 0-5 ng ml-1 Cd) C,F,Cl CHF and CCl measured in DCP discharge using wavelength modulation laser absorption spectroscopy with semiconductor diode lasers. (Detection limits 0.6-1.5 ppb using C1 837.6 nm non-resonance line) As for Br 9511025 C Chlorinated hydrocarbons AE;MIP;L Fluoromethanes Polycyclic aromatics Organic carbon X-ray emission 9511568 AE;MIP;L 9512304 9512882 AA;F;L 951915 Cd Herbal drugs Chinese traditional medicine AA,ETA;L AA;DCP;G 9512252 951249 Cd c1 Chlorinated hydrocarbons Halogenated GC effluents; Chlorinated hydrocarbons Pesticides MS;ICP;L AE;MIP;L AE;MIP;L 95 1527 9511025 9511928 c1 c1 c1 As for C.(Limit of detection using Beenakker cavity was 0.5 ng ml-'). Review (no refs.) of application of GC-MIP-AES for determination of chlorinated aromatic compounds and phenols. Comparison with GC-MS. Comparison of pharmacokinetics of trace element Co and its protoporphyrin chelate in rats. GFAAS used to study levels of Co in tissues and blood plasma following treatment with Co (chloride or protoporphyrin) chromatography using Hypersil SAS C1 column with mobile phase comprising 68% methanol at pH 4.5.(Limits of detection in ng range). heterophilus sweet and its products by formation of ion pair with CI-(NH~)~(CSN),- and separation by solvent flotation. suitable solvents and leaching with simulated rain. CrV' determined by extraction with NaOH (around 12% of total Clr) Metalloporphyrins separated by liquid Indirect determination of alkaloids in Leonorus Speciation of Cr by sequential extraction with As for Cd. (Calibration range 0-80 ng ml-' Cr) As for Cd. (Calibration linear up to 10 pg ml-'; limit of detection 8.5 pg 1-') Free Cu separated from complexed species using mixed phase column HPLC coupled to ICP-AES Evaluation of GC-MIP-AES for simultaneous detection of F and 0 containing molecules. Hydrogen and methane reagent gases added to produce carbon coating on discharge tube thereby eliminating spurious 0 peaks caused by attack by fluorine radicals Chlorinated aromatic compounds c o Cobalt protoporphyrin AA;ETA;L 9511 129 c o (Cr) Cr Metalloporphyrins MS;ICP;L 9511977 Alkaloids AE;ICP;L 94lC3410 Compost from municipal AA;F;L waste 95/47 Chinese traditional medicine AA;ETA;L Herbal drugs AA;F;L 9512252 9519 15 Cr c u Dyes AE;ICPL 951c2932 c u Fluoroethers AE;MIP;L F 9413257 370 R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 2 (continued) Technique; atomization; analyte form* Element Matrix Sample treatment1comments Reference 951249 9511568 9 51 1977 9512222 9512304 9413027 94lC3404 9413054 9413054 9512222 9413257 9511225 94lC3406 F Fluorinated hydrocarbons AA;DCP;G As for C1.(Detection limits approximately 70 ppb As for C. As for Co. (Limits of detection in pg range for hemin). Ultrasonic slurry sampler used for automated determination of Ni and Fe (contained in catalyst fines 0.5 to 50 pm in size). Concentration range 0.02 to 1 mg kg-'. using F 739.87 nm non-resonance line) As for C. Cold Hg vapour generated from micellar media using sodium tetrahydroborate. Signal obtained using anionic surfactant Na dioctylsulfosuccinate solution was 50% higher than for conventional Hg cold vapour generation. Samples digested with HNO,/H,SO,/H,O mixture. Mercury cold vapour generated using tin'") chloride reducing agent. Determination by GFAAS at 235.7 nm. (Concentrations approximately 0.6 pg g;' Hg in medicines) Samples diluted with water and analysed directly. Calibrated using standard additions.Limit of detection 0.9 ng ml-' and recoveries 75-125%. As for K. (Limit of detection = 2.3 ng ml- '-I). As for Fe. Concentration range 0.1 to 30 mg kg-'. As for F. GC-MIP-AES used to study effect of molecular structure and condition of discharge tube on elemental response for 0. Response found to vary with both parameters. Sample (2 g) heated at 60 "C for 5 min with 5 ml of 3 mol 1-' KOH-ethanol solution and then shaken for 1 min to saponify the oil. Matrix modifier was added (0.8 ml of 2% PdC1,) and solutions made up to 10 ml prior to analysis. (Concentrations 100-165 pg kg-' Pb in oil) As for Cd. (Calibration linear up to 100 pg ml-'; Limit of detection 200 pg 1-') 22 chelating agents tested for enhancement of Pb signal in HGAAS.System optimized using 1-(2- pyridylazo)-2-naphthol-6-sulfonic acid. (RSD at 50 ng ml-' level was 3.9%) As for Cd. (Calibration range 0-50 ng ml-' Pb) AOAC method in which sample equilibrated at 60 "C and then mixed with lecithin solution in cyclohexane prior to measurement of Pb using GFAAS. Reproducibility was around 30% (16 labs) and repeatability 11% and 7% respectively for soya bean oil and cocoa butter. Samples diluted fourfold with IBMK or ethanol but poor recoveries obtained when samples contained toluene hexene heptanol heptanal or their mixtures. Effect buffered by adding 20% heptan-1-a1 and 70% ethanol as solvent Samples diluted (at least 10 fold) so that final solutions contained approximately 20% toluene:80% ethanol.Standards prepared in same matrix. (Concentrations 50-2000 pg g-' Ru) Sulfur containing compounds converted to H,S by pyrolysis at 1050°C in presence of H gas. H,S trapped in liquid nitrogen trap and then flash vaporized into He MIP. (Detection limit 400 pg g-' when 180.73 nm line used) As for As. (Concentration range=0.05 to 10 pg 1-') Sample (1 ml) digested with 0.5 ml HNO and then diluted to 10 ml with H,O. 5 ml of resulting solution diluted to 10 ml with 10 mg ml-' nickel nitrate (matrix modifier) Torch comprised two concentric quartz tubes the inner of which held the electrode which coupled to the microwave field. Samples introduced by nebulization through tubular electrode or vaporization from cupped electrode. (Limits of detection 0.03 and 0.3 pg g-' respectively) F Fluoromethanes Fe Metalloporphyrins X-ray emission MS;ICPL Fe Edible oils and fats AA;ETA;slurry H Polycyclic aromatics Hg Surfactants AE;MIP;L AA;CV;L Hg Chinese traditional patent medicines AA;CV;L K Acetone AA;ETA;L Na Acetone Ni Edible oils and fats 0 Fluoroethers 0 Organic compounds AA;ETA;L AA;ETA;slurr y AE;MIPL AE;MIP;L Pb Fried oil AA;ETA;L Pb Pb Herbal drugs Chelating agents AAF;L AA;HG;L 9519 15 9413030 Pb Pb Chinese traditional medicine AA;ETA;L Edible oils and fats A A;ETA;L 9512252 9512547 Rh Organic solutions AA;F;L 9413 127 Ru S Hydroformulation solutions AA;F;L 9511839 9412996 Aqueous sulfur compounds AE;MIP;L 9413002 951973 Sb Se L-Cystein (reducing agent) AA;HG;L Chinese oral medication AA;ETA;L 951332 Si Organic samples AE;CCP;L Journal of Analytical Atomic Spectrometry December 1995 Vol.10 371 RTable 2 (continued) Technique; atomization; analyte form* Element Matrix Sample treatment/comments Reference Sn Alkyltin MS;GD;L Determination of tetraethyltin and tetrabutyltin using 95/c29 59 GC coupled lo rf glow discharge source mass spectrometer. (Detection limits approximately 1 pg Sn) Study of solvent enhancement effect of methanol ethanol propanol and acetone. Optimum signal obtained with 20% v/v propanol in 0.5 mol 1-' HC1 Indirect method for determination of trace amounts (200-2000 ng m1-l) of nonionic surfactants by precipitation with tungstophosphates Study of effect of five sulfonate containing and sulfate containing surfactants in FAAS determination of Yb. Sulfonate containing surfactants found to give enhancement but sulfate containing surfactants gave suppressions protoporphyrins from whole blood of lead poisoned patient.(Limits of detection in ng range.) Determination of trace elements (Cr Cu Fe Mn Ni) in organic matter by introducing powdered sample into ICP. (RSD 6-13%; recovery 95-115%) Sample diluted 10 fold with 2-ethoxyethyl acetate and introduced directly to MIP (oxygen-nitrogen) for MS determination of Cr Cu Fe Mn Ni and Pb. (Limits of detection 0.01 to 0.1 ng ml-l.) desolvation far analysis of volatile solvents (hexanes methanol tetrahydrofuran acetone and dichloromethane) using conventional sample introduction rates (1-4 ml min-l). (Limits of detection similar to aqueous) determination of Ag Cu Fe Ni and Pb in IBMK solutions chromatography can be operated in either atomic or molecular t i e .similar to EI) mode depending on forward power and plasma gas flow Impurities (Al Co Cr Cu Mn Ni and V) preconcentrated on graphite powder (40-100 mg) by distilling off sample (2-10 8). Resulting powder mixed with 3-5% NaCl and impurities determined by AES. (Limits of detection approximately Review (642 refs.) of analysis of chemical and 951 1924 XRF or AA;F;L AA;F;L As for Co. Applied to determination of Zn Use of ultrasonic nebulizer with membrane Use of atom concentrator tube-FAAS for 9413296 Low pressure ICP-MS detector for gas 941C3456 1 ng g - 9 petrochemical industry products in China during period July 1991 to June 1993 enhancements with ethanol solutions. Electron density and mass flow rate of aerosol found to increase with increasing ethanol concentrations impurities in trimethylaluminium and triethylindium using ETV-AES.Time-temperature programme separated impurities based on their volatility Discrete nebulization of one drop (< 60 pl) of non- flammable chlorinated solvents into a fuel lean air- acetylene flame for determination of extracted chelates or ion paired complexes of Ag Cd Co Cr Cu Fe Mg Mn Ni Pb and Zn Determination of Al Cr Cu Fe Ni and Pb in olive and sunflower oils using GFAAS. All elements except Cu and Pb required use of L'vov platform to eliminate matrix interferences. (Limits of detection 1.3- 14.9 ng g-') Study of effect of solvent (water methanol and chloroform) and solvent load on background spectra and visual features of ICP.Investigation of mechanism of sensitivity Determination of volatile and non-volatile trace V Water miscible solvents AA;FL Nonionic surfactants Anionic surfactants 9512766 951291 Zn Metalloporph yrins Various ( 5 ) Organic matter Various (6) Photoresist solution MS;ICP;L AE;ICP;S MS;MIP;L 9511977 9413093 9413188 Various Volatile solvents AE;ICP;L 9413250 AA;F;L MS;ICP;G Various (5) IBMK Various Organometallics and organohalides AE;arc;S 95/24 Various (7) Ferrocene Various Various Chemical products Ethanol solutions Various AE;ICP;L 95/67 9 51293 Semiconductor grade organometallics and process chemicals Various AE1CP;L 951299 AA;F;L 951304 Various ( 10) Chlorinated hydrocarbon extracts Various (6) Vegetable oils AA;ETA;L 951409 Various Organic solvents AE;ICP;L 951525 372R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10Table 2 (continued) Technique; atomization; analyte form* Element Matrix Sample treatment/comments Reference Various Chloroform AE1CP;L Study of effect of solvent load on axial emission 951526 profiles for Mg I Mg 11 C I C2 and CN.Former two parameters indicated 'robustness' of plasma under different operating conditions and latter two boundaries of aerosol channel and atomic plasma in 'tailflame'. Elemental speciation of heavy metal complexes with humic substances and organo-iodine compounds in natural waters (around 1 ng g-') by LC-ICP-MS utilising isotope dilution with continuous on-line introduction of isotopically enriched species unspecific spike solution Determination of volatile and non-volatile trace impurities in trimethylaluminium phosphorus tribromide and phosphorus oxychloride using ETV-ICP-MS.Initial sub-ambient temperatures of ETV allowed direct analysis of difficult to handle samples. Single and multi-element GFAAS coupled with various sample processing procedures used to determine critical metal impurities down to 10-20 ng g-' Low pressure ICP-MS system described which can be used as either element specific or structure specific (similar to EI) detector for GC. Degree of fragmentation controlled by plasma gas flow and forward power. (Detection limits 10-500 pg). impurities in organometallic semiconductor grade reagents. Quantitative study of mechanism of ethanol enhancement in ICP-AES by application of Raoult-Clausius-Clapeyron and Einstein- Boltzman-Saha equations chloroform) on plasma electron density maps obtained from intensity of one argon line (calibrated against electron density obtained from Stark broadening).Study of effect of ethanol load on plasma excitation temperature and sensitivity for Al Cd Cr Fe Mn Mo Na Pb and V. Optimal detection limits obtained at 15% ethanol (corresponding to maximum excitation temperature) Indirect methods evaluated for determination of papaverine hydrochloride in pharmaceutical preparations by precipitation of ion associates with several metal containing complex anions. Ammonium reineckate gave best recoveries Determination of trace elements in headache magistral and its six Chinese crude drugs Automated calibration method for determination of element ratios and quantitation in unknown samples using GC-MIP-AES (to be used in conjunction with GC-MS) Investigation of source and interface variables of electrospray MS for application to elemental analysis and to provide information on valence state molecular form and composition of solvation sphere ETV-ICP-MS used for determination of trace Study of effect of solvent load (water methanol and 9512780 95/C2917 9513065 Various Humic complexes and M S; IC P;L organo-iodine compounds 951529 Various ( 15) Semiconductor grade organometallics and process chemicals MS;ICP;L 951532 Various (25) Morpholine monoethanolamine and diethanolamine Various (6) Organic compounds AAETAL MS;ICP;L 95/C723 95/ 1464 Various Various Organometallics AE or MS;ICP;L AE1CP;L 9511912 9511961 Ethanol Various Organic solvents AE;ICP;L 9512188 Various (9) Ethanol AE;ICP;L 9512399 (Various) Papaverine hydrochloride AE;DCP;L 9512517 Various (10) Chinese medicine Various Unknown organics AA;F;L AE;MIP;L Various Methanol MS;-;L CATALYSTS- A1 TiC14/Si04 polyolefin catalyst AA;F;L Determination of Al Mg and Ti in TiCl,/SiO catalyst modified with MgC1 to produce different Mg Ti ratios and study of effect on polymerization of ethylene and propene (homo and copolymers) Determination of oxidation state of Ge promoter on a carbon supported Pd hydrogenation catalyst.Two types of Ge identified (Ge"+ and GeO alloy). As for A1 9512746 XPS and AE AA;F;L 9511 160 95/2746 Pd/carbon catalysts Ge Mg TiCl,/SiO polyolefin catalyst Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 373RTable 2 (continued) Technique; atomization; analyte form* Sample treatment/comments Element Matrix Pd Hydrogenation catalysts Reference 9511904 AE;F;L Determination of Pd and Na in catalysts based on Pd/Na/Ag on aluminium supports.Catalyst dissolved under pressure at 160-170 "C using 3:2 HNO, HC1. Solutions filtered to remove AgCl precipitate prior to analysis XPS TEM SEM electron diffraction IR ICP-AES and photomicroscopy used to characterize structure and Pd distribution on colloidal catalysts prepared by one-step method Sample (2 g) heated at 650 "C for 3 h in stream of H ( 5 1 h-I) cooled in stream of N and then digested in aqua regia. Solution evaporated 4 ml HC1 added and solution evaporated again. Residue dissolved in 2 mol 1-' HC1 and Pt extracted into IBMK with triphenylphosphine extraction into IBMK.Results compared favourably with those obtained by fusing sample with potassium pyrosulfate. oxidation state of Ti also determined using XRD and EPR N,O-C2H2 flame. Lower concentrations determined using GFAAS. For FAAS determinations standards matrix matched by adding aluminium. As for Pt but solution analysed directly without 9513 103 As for Al but crystal structure of catalyst and 9512746 Higher concentrations determined using FAAS using 94/c 3 397 Comparison of sample preparation methods Polymer supported colloidal catalysts AE;ICPL and XPS and TEM and SEM 9 5/27 7 3 Pd Pt Cobalt oxide catalyst AA;F;L 9513103 Cobalt oxide catalyst AA;F;L Rh TiC1,/Si02 polyolefin catalyst AA;F;L and EPR Ti V Catalytic cracking catalysts AA;F or ETA;L Various Exhaust catalysts (noble metals) Various Pd catalysts AE;ICP;L or AA;F;L 951258 951C483 951891 Spatially resolved analysis of new catalysts for determination of Pd distribution and used catalysts to screen for poisons using UV laser ablation.Approximately 1.2 g of KOH pellets melted in Ni crucible spread onto crucible walls by spinning manually and then cooled. Approximately 0.2 g of dried catalyst added to crucible and remelted. Cooled melt leached with H20 and filtered prior to determination of Al B Na and Si. Samples dissolved in HF HNO and H2S04 prior to determination of Al Fe Mo Na Ni Si Ti and V using FAAS. RSDs were <4% for nearly all determinations. thickness and volume of material excited based on fundamental parameters.Program described for calculation of critical sample MS;ICP;L Various (4) Borosilicate catalysts AE1CP;L Various (8) Aluminosilicate catalysts AA;F;L 9511216 XRF;-;S Various Catalysts 9511777 INORGANIC CHEMICALS AND ACIDS- Ag Silver halides Thermal lens XRF';-;S Study of thermal lens effects produced by an argon ion laser on silver chloride and bromide suspensions After acid digestion the sample was diluted with water and the molybdoarsenic acid was complexed with tri-n-octylamine in molten stearic acid; following extraction the solidified stearic acid was separated and pressed into a disc with boric acid; LOD= 1.2 pg g-' diethyldithiophosphoric acid to separate from pentavalent species Direct examination by XRF and electron probe microanalysis for YO levels of As Methanol was added to the sample which was heated with bubbling of inert gas to form trimethylboric acid; this was separated using an aqueous solution of a resin and the resulting solution was evaporated in high purity inert gas and the residue dissolved in acid; LOD= 1 ng ng-' determination of Ba with an LOD of 10 mg 1-' Quantitative extraction of trivalent As using Investigation of effect of pH adjustment on Investigation of interference effects in flame Use of cadmium internal standard to correct for 95/C1989 9413349 9512298 slight changes in the solution matrix effect with concentration; LOD = 5 mg 1-l 9511 87 1 9511871 As Molybdoarsenic acid As Sulfuric acid AE;ICP;L 95/12 10 Fertilizer waste sludge Sulfuric acid XRF;-;S MS;ICP;L As B 9511747 9511298 Ba Industrial waste AA;F;L Ca c1 Aluminium chloride Photographic developer AA;F;L XRF;-;L 374R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 2 (continued) Technique; atomization; analyte form* Sample treatmentlcomments Reference Element c o c u Matrix Sodium chloride Titanium dichloride AA;ETA;L Investigation of effect of sodium chloride matrix on signals using dual cavity platform Molten salt was decomposed in nitric acid evaporated to dryness and dissolved in hydrofluoric acid; after extraction with dithiocarbamate into 4-methyl-2-pentanone the organic phase was heated to dryness and treated with nitric and hydrochloric acids; LOD = 0.01 pg g-' Description of gaseous sample introduction based on a by-pass-backflush-balancing gas injection system constructed from non-metallic tubing and flowmeters and a graphite capillary inlet; LOD=0.7 ng ml-' By-pass-backflush-balancing direct sample injection system (see 9413246) Evaluation of flame photometric instrumentation for AOAC official method; assessment based on oxalate and citrate extractions of NIST standards Matrix matching and standard additions methodology using FI sample introduction The sample was introduced to a transversely heated tungsten tube atomizer as a slurry; LOD = 2 ng g-' Fusion of sample with ammonium hydrogen sulfate; minimal interference effects from the flux were observed.Use of a strong reducing agent to convert nitrate to nitrogen gas and detection of UV absorption As for Li As for As The sample was distilled in a mixture of phosphoric hydroiodic and hydrochloric acids in the presence of zinc and the SeI thus produced was collected in a mixture of perchloric and oxalic acids and potassium permanganate prior to generation of the hydride for the ICP; LOD = 0.05 ng ml- Investigation of blanks encountered in the determination of Si at sub-ng g-' levels for electronic grade applications Sample (0.1 g) was fused with sodium hydroxide and sodium chlorate in a silver or gold crucible and dissolution of the resulting melt in hydrochloric acid 951212 9413308 As for Co 951212 An oxidizing agent and a fuel are introduced to a gas 951874 flue channel and metal particle content is calculated on the basis of intensity measurement Comparison of high-performance chelation ion chromatography and ICP-OES for determination of Ba Ca Mg and Si Effect of nitric acid on determination of REEs using both pneumatic and ultrasonic nebulization Solid phase extraction of trace elements using ammonium hexamethylenedithiocarbamate mixed with polyurethane foam and packed into disposable syringes; the complexes thus formed were extracted into IBMK or 4 mol 1-' nitric acid prior to detection; recoveries > 98% reported Preliminary separation of analytes including REEs carried out by ion-exchange chromatography on Dowex SOW-X(H) resin Selection of lines for analysis based on sensitivity and spectral interference criteria Method described for the detection of trace level impurities (Al Bi Cd Co Cu Fe Mn Ni Pb Si and Sn) Study of the effect of acids on vaporization and interference effects The liquid-phase sample was collected and evaporated and the residue digested in concentrated ammonia solution and analysed by ICP-MS using ultrasonic nebulization 9511224 951c2944 9413001 AA;ETA;L Fe Hydrogen chloride gas AA;ETA;G 9413246 Fe K Hydrogen chloride Fertilizers AE;MIP;G AE;F;L 9413260 951410 Sodium antimonate Molybdenum oxide trih ydrate AA;F;L A A;ETA;S 9511957 9413139 K Li 95/35 Li Lithium niobate AE;ICP;L AA;-;G 951872 N Nitrate 9 513 5 9511210 951928 Nb Sb Se Lithium niobate Sulfuric acid Calcium carbonate AE;ICP;L AE;ICP;L AE;ICP;HG 951c3032 95/45 Si Si Ultra pure acids B A A; ETA;L AA;F;L Zn Sodium chloride Alkali Combustion gases metals AA;ETA;L AE;F;G Alkaline Brine earths AE1CP;L REE Nitric acid AE;ICP;L AA or AE;F or 1CP;L Various (9) Sodium salts Various Aluminium sulfate solutions AE;ICP;L 9413056 Various (8) Various ( 11 ) Palladium compounds Tantalum pentoxide AE;ICP;L A A;ETA;L 9413 129 9413 147 Mineral acids Tungsten hexafluoride MS;ETV-ICP;L MS;ICP;L 9413252 9413278 Various (7) Various (12) Journal of Analytical Atomic Spectrometry December 1995 Vol.10 375 RTable 2 (continued) Element Matrix Technique; atomization; analyte form* Various Osmium powder AE;arc;S Various (7) Hydrogen chloride AE;ICPG Various Fertilizers MS;ICP;L Various ( 15) Phosphorus tribromide and MS;ETV-1CP;S ox y c h 1 o ri d e Various Various Hydrogen chloride gas AE;ICP;L Copper electrolyte solutions XRF;-;L Various (8) Ammonium fluoride AA;ETA;L Various (4) Chloride-ammonia palladium AA;F;L Various Arsenic and selenium AA;ETA;L electrolyte Various (10) Chlorine Various Aluminium fluoride Various (10) Hydrofluoric acid Various Lithium niobates Various Various Various Calcium sulfate Lithium chloride and carbonate Hydrogen peroxide and phosphoric acid NUCLEAR MATERIALS - B Magnesium (for uranium production) AE;ICP;G AA;ETA,L MS;ICP; L AE;ICPL MS;LA-ICP;S AA;F;L AA;ETA;L AE;arc;S Sample treatment/comments Reference Evaporation of matrix in a quartz boat with graphite powder as impurity trap Sample was introduced to the argon gas flow of a sealed ICP source at atmospheric pressure; LOD for Sn was 49 ng g-' and C was 271 ng g-' Separation and identification of metal chelates present in commercial fertilizers using gel- permeation chromatography Thermal separation of analytes from matrix using modified ETV with sub-ambient temperatures for multi-element screening for volatile and non- volatile impurities in semiconductor grade process chemicals Method based on trapping of volatile chlorides in chilled de-ionized water traps and ultrasonic nebulization to achieve required sensitivity dispersive XRF system with a flow-through cell for continuous monitoring of As Cu and S; LOD for Cu of 0.7 g 1- ' in the presence of 0.8 g I-' Ni reported Direct determination of ng g-' levels of impurities in up to 20% ammonium fluoride solutions; a multi- step ion exchange procedure was for separation and preconcentration was used to verify accuracy of the former procedure and to improve detection limits Method for the determination of Pd and impurities (Cu Ni and Zn) Sample (pure selenium) was digested in a quartz dish under class 100 clean room conditions using nitric acid (for pure arsenic mixed 3:2 with hydrochloric acid) evaporated to dryness and hydrogen bromide added to remove matrix; the residue was dissolved in nitric acid and diluted to 10 ml Formation of a pure chlorine rf discharge employed to determine trace element impurities in sample; LOD for Sn was 25 ng g-' and for C was 725 ng g- ' matrix using nitric acid extraction; LODs 1-3 ng g-' Comparison of isotope dilution and conventional ICP-MS for the determination of trace heavy metals of interest in the microelectronics industry Sample (100 mg) was fused with 2 g of ammonium hydrogen sulfate and dissolved in 20 ml water and mixed with 10 ml of sulfuric acid 1 g of tartaric acid and 1 ml of hydrogen peroxide and diluted to 100 ml; Yttrium was used as internal standard Semiquantitative and quantitative analysis of powders using laser ablation of pelleted sample Formation of an emulsion using isooctylphosphorate and poly ( bissuccinamide) and hydrochloric- sulfuric acids; the pH was adjusted to 5 using acetic acid-sodium acetate buffer and after 8 min extraction the aqueous layer was discarded while demulsification was performed prior to analysis; LODs for Cu Co and Ni were reported in the pg g-' range and recoveries were 92-102% A safe method of preconcentration and evaporation of hydrogen peroxide using a dynamic vacuum was described; interferences in the determination of K and Na in phosphoric acid were overcome by standard addition sample dilution and optimization of the furnace heating programme 9 51240 951329 951418 951532 Description of application of on-line energy Quantitative extraction of Co Cu Fe and Ni from 951C3030 The magnesium sample was converted to the oxide and ground with conducting graphite containing lithium fluoride and gallium oxide; 30 mg of the mixture was excited in a dc arc operated at 12 A; an RSD for B of 5.5% was reported in the 1-10 pg g-' concentration range 95/C621 9511740 9511876 9511931 9511934 9512 18 5 9512329 9512440 9512503 9512616 9512834 951214 376 R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 2 (continued) Technique; atomization; analyte form* Element Matrix Sample treatment/comments Reference B Uranium oxide AEi-i- The sample was preconcentrated using a multi-polar evaporator by heating at 1 min intervals up to 2000°C and the condensate was collected in a cold trap and was treated with 1 drop of ethanolic 2% linear bakelite solution and examined spectrographically using gallium as internal standard As for B; an RSD for Cd of 7.6% was reported in the 1-10 pg g-' concentration range Sample (1 g) was spiked with l6'Dy; the bulk of the matrix was removed by ion exchange resin and Dy was separated from the other REEs using P507 extractant resin I5'Gd and 233U were used as the diluents and quantitatively added to the samples; Gd and U were separated using DHDECMP resin and detected with a thermal ion source MS high-pressure asher; LOD =0.1 pg ml-l evaporated to near dryness and a mixture of nitric and hydrofluoric acids was added to dissolve trace tantalum which was separated from the uranium matrix by TBP levextrel resin chromatography Analysis of leachates of spent fuel and vitrified highly active waste and dissolver solutions; investigation of the formation of polyatomic ions of Tc collector ICP-MS instrument mercury as a catalyst and 233U was extracted with 30% tributyl phosphate in dodecane Investigation of hydride interference on the determination of minor actinide isotopes The sample was dissolved in nitric acid and passed through a TBP levextrel chromatographic column using nitric acid as the eluent; Cs K Li and Na were determined in the eluate The method involved a pre-separation of uranium from the analytes using HPLC which was consigned to waste and the eluate was then switched back to the ICP-MS line Transition metals (Co Fe Mn Ni) were concentrated and separated from boric acid using cation chromatography resulting in enrichment factors of up to 500 fold for a 1 litre sample; LOD's in the range 0.02 ng 1-' for Co to 2 ng 1-' for Fe were reported Qualitative examination of fuel residues containing metallic and oxidic phases by SEM and X-ray microanalysis; ICP-MS used to identify and quantify Mo Pu Rh Ru and Zr content of fines determination of chemical speciation for Pu Sr and U in the solid phase Separation of trace elements using a column of PTFE powder (330 pm) coated with tributyl phosphate as extractant; the eluent was passed directly into the ICP for the determination of Mo and other elements with recoveries in the range 91-110% reported Samples were dissolved in nitric acid and the filtered residue was dissolved in a mixture of nitric and hydrochloric acids; both standard addition with internal standard and isotope dilution protocols were adopted for determination of Mo Pd Pu Rh Ru Tc U and Zr procedures in the determination of major elements in Pu nitrate solutions from reprocessing Np- containing experimental nuclear fuels Gd- containing natural and irradiated uranium dioxide and U-Pu-Zr alloys 951992 Determination of leachable or 'active' S using Parr The sample was converted to uranyl nitrate and Measurement of U isotope ratios using a multiple The sample was dissolved in nitric acid containing 9413215 Use of extended X-ray fine structure spectroscopy for 94lC348 1 951107 Use of standard additions and isotope dilution Cd DY Magnesium (for uranium production) Uranium oxide AE;arc;S IDMS 951214 9413204 Gd Gadolinium oxide-uranium IDMS oxide pellets 9512578 S Graphite nuclear packing AE;ICP;L Ta Uranium compounds AE;ICP;L 9413125 951289 99Tc Spent nuclear fuels MS;ICP;L 951314 U Uranium isotope mixtures MS;ICP;L AE;ICP;L 9512398 9512812 233U Uranium/aluminium alloy fuel Actinides Thorium and Uranium MS;ICP;L AA or AE;F;L 9513 15 951290 Alkali Uranium dioxide metals REE Uranium materials MS;ICP;L 951C484 Transition PWR primary water metals MS;ICP;L 9413110 Various Spent nuclear fuels MS;ICP;L Various Nuclear waste EXAFS AE1CP;L Various ( 1 1 ) Uranium dioxide Various (8) Spent nuclear fuels MS;ICP;L 951313 Various Nuclear samples MS;ICP 95lC470 Journal of Analytical Atomic Spectrometry December 1995 Vol.10 377 RTable 2 (continued) Element Matrix Various Nuclear waste waters Various Spent nuclear fuel corrodant solutions Various Uranium dioxide spent fuel Various Uranium metal and thorium oxide Various ( 11) Uranium Various Radioactive mixed waste Various (18) Nuclear grade uranium compounds Various (21 ) Uranium silicide fuel Various Spent nuclear fuels Technique; atomization; analyte form* MS;ICP;L MS;ICP;L MS;ICP;L AA; ETA;L AE;ICP;L AE or MS;ICP;L AE;ICP;L AE or AA;ICP or ETA;L MS;ICP;L Sample treatmentlcomments Reference Study of 99T~ lZ9I and tritium migration using 951005 isotope dilution protocol satisfactory but poor results were obtained for Am and Cm due to statistical and background uncertainty Separation of REEs and actinides from the matrix by high pressure ion chromatography for removal of isobaric interferences sample on a small column of Chelex-100 eluted with nitric acid and detected by Zeeman-effect ETAAS Impurities were separated from the matrix following a single step extraction using tributyl phosphate- carbon tetrachloride extraction system Comparison of separation techniques for clean up of samples involving (a) liquid extraction using tri-n- octylphosphine oxide in cyclohexane and (b) extraction chromatography using an Eichrom TRU-Spec column Separation of impurity elements from the uranium matrix by extraction with tributyl phosphate; RSDs <2.2% for all elements except B (9.4%) Chemical separation of REEs and other trace elements from the matrix for ICP-OES; Ag determined by ETAAS chromatography procedures were developed for the separation of fission Cs from Ba for the lanthanides and the actinides to remove spectral interferences Direct analysis for Np Pu and U was found to be 95/C5 15 95/C8 17 Trace elements were preconcentrated from the 951890 951895 9511386 - 951191 1 9512336 Instrument installed in a glove box and ion 9512397 *Hy indicates hydride generation and S L G and S1 signify solid liquid gaseous or slurry sample introduction respectively.Other abbreviations are listed elsewhere. ~ SRMs using isotope dilution thermal ionization mass spec- trometry (95/1345).These SRMs are suitable for use as primary or quality control standards for determination of sulfur using XRF or high-temperature combustion methods. The former technique is particularly suitable for on-line sulfur determination in view of its robustness stability non-destructive nature and amenability for use in inherently safe instrumentation. Equipment of this type is produced by several manufacturers and has been applied (e.g. 95/1685) to determination of sulfur (0.01-5 % m/m) in refinery process streams (naphtha kerosine light and heavy oils etc). XRF has also been applied to analy- sis (e.g. Ba Cr K and S) of drilling fluid containing solids suspended in a liquid phase comprising oil and brine (95/1590). 2.1.2. Fuels Most of the work carried out during the review has been driven directly or indirectly by the growing concern over the environmental impact of burning fossil fuels.Determination of lead in gasoline continues to attract attention but interest is also being extended to other elements which could have a potential environmental impact (e.g. As and Cd). Most common methods for determination of lead in gasoline involve breaking down the alkyllead compounds with halogen (e.g. iodine) prior to analysis. Moseley et al. (95/C559) have extended this approach for GFAAS determination of As in gasoline. The authors reported simultaneous determination of As and Pb using a GFAAS spectrometer equipped with a dual galvanometer drive system to control the rapidly alternating selection of both source and wavelength.An alternative method for determination of As in thermally cracked gasoline has been reported which involves combustion followed by hydride gener- 378 R Journal of Analytical Atomic Spectrometry December i ation AAS (95/1087). The reported limit of detection for this method was 5 ng 8 - l . Direct nebulization of volatile hydrocarbons such as gasoline into flames or plasmas can often cause problems such as quenching impaired sensitivity high noise enhanced back- ground and generation of interfering species. A possible solu- tion is to introduce the samples in the form of microemulsions. Wei and co-workers have adopted this approach for measure- ment of Co naphthenate (95/943) and ferrocene (95/2837) in gasoline using FAAS. In these studies the microemulsions were formed by adding the gasoline samples to approximately 6 ml of butanol and 2 g of sodium dodecyl sulfate and diluting to 25 ml with water.The authors also reported application of the method to determination of lead in gasoline (94/C3405) but it is not clear how problems associated with selective volatiliz- ation of the different alkyllead compounds were overcome since no steps were taken to break these down prior to analysis. Use of microemulsions has also been adopted by Al-Swaidan (95/1308) for determination of lead and cadmium in petroleum based fuels using ICP-MS. The mean Pb and Cd concen- trations detected were 0.15 and 0.17 pg g-' respectively in aviation turbine fuel and 0.35 and 0.01 pg g-' in diesel fuel. The authors also reported levels of Pb and Cd in leaded gasoline of 901 and 0.085 pg g-' respectively. However this level of lead seems remarkably high for a normal leaded gasoline. The results were discussed in relation to sources of the metals and possible environmental impact and health risks.In many instances determination oftotd lead in gasoline (or environmental samples) presents only a partial picture since properties of the different chemical forms of lead (e.g. alkyllead partially alkylated ionic forms and inorganic lead) can vary 1995 Vol. 10enormously both in terms of their function as gasoline additives and in their toxicity. A simple method of distinguishing alkyl- lead and inorganic lead in organic solvents (e.g. gasoline) has been reported which involves carrying out extractions with and without the addition of halogen (ICl) to break down the alkyllead compounds (95/213).If full speciation is required however then the normal approach is to use GC with some form of atomic spectrometric detection. The state-of-the-art in speciation of organolead compounds using this approach has been reviewed (59 refs.) and an overview provided of procedures applicable to analysis of water samples sediments and biologi- cal materials (95/1). The GC-AES approach has also been applied to determination of the gasoline additives tricarbonyl- (2-methylcyclopentadienyl)manganese and bis( pentamethyl- cyclopentadieny1)manganese (95/2857). Limits of detection were 62 and 69 pg g-' respectively and RSDs less than 6.6% (n= 10). The alternating current plasma source used in this study was claimed to offer a cheap and easily constructed alternative to commercially available GC-AES systems although sensitivity (at least for Mn) appeared to be somewhat poorer.Copper in jet fuel is highly undesirable since this metal can degrade the oxidation stability of the fuel even when present at very low (ng g-') concentrations. In cases where significant copper is present in the fuel it is common practice to add 'metal deactivators" to render the metal harmless. In order to fully understand the behaviour of these deactivators it is necessary to be able to measure the various forms of metal complexes formed. Taylor and Synovec (95/102) have reported use of HPLC-FAAS to study copper compounds formed by interaction between jet fuel and copper in the presence and absence of Du-Pont metal deactivator (active component N,N'-disalicylidenepropylene- 1,2-diamine).Detection limits were around 10 ng g-'. Sulfur levels in fuels such as diesel and gasoline are continu- ally being driven down by increasingly tight legislation designed to reduce sulfur dioxide atmospheric pollution. Measurement of sulfur at these lower levels is stretching the analytical performance some older EDXRF equipment tra- ditionally used for this type of analysis to such an extent that precision and accuracy is severely degraded. This has been highlighted by recent changes in US government regulations which made ASTM D2622 (WDXRF) the required method for S in petroleum products such as reformulated gasoline and diesel fuel.However recent developments in EDXRF instru- mentation have been shown to go some way to redressing this balance and provide performance comparable to that exhibited by WDXRF (95/C2915). For heavier fractions such as fuel oils concentrations of Ni and V are also of importance in addition to S. Nickel compounds have carcinogenic and muta- genic effects and their emission levels must therefore be tightly controlled while V can form low melting-point vanadates which can cause superheater corrosion. Several methods have been developed by national normative institutions for determi- nation of these elements in fuel oils. However many of these methods are characterized by poor repeatability and reproduc- ibility. A method has been proposed for direct determination of Ni and V in fuel oils using FAAS after simple solvent dilution (94/3124).The method has been tested in a round- robin comprising fifty-four European laboratories and has been shown to give significant improvements in repeatability and reproducibility over that provided in the Institute of Petroleum method IP288. For a fuel oil standard containing 30pg g-' Ni and 50pg g-' V the repeatabilities were 3.4 and 3.8 pg g-l and the reproducibilities 8.1 and 11.1 pg g-' respectively. Comparisons with independent analytical tech- niques were also carried out in order to validate the accuracy of the method. 2.1.3. Lubricating oils Inductively coupled plasma atomic emission spectrometry has long been used for determination of additive and wear elements in new and used lubricating oils and an overview of these applications has been published during the review period (95/2813).Readers may also be interested in an automated workstation which has been applied to preparation of oil samples for ICP-AES analysis (95/C556). The system described carried out gravimetric dilution of the samples with kerosene followed by vortex mixing and was claimed to have a through- put rate of one sample every 78 s (i.e. fast enough to keep pace with the ICP-AES instrument). In a study carried out on CF-188 Hornet aircraft engines using INAA (95/2308) how- ever the authors showed that most useful wear data could be obtained from filter debris analysis and claimed that little useful information could be obtained by analysis of the oil from a finely filtered engine system.This situation does not appear to be typical however since ICP-AES and AAS still form a large proportion of the core techniques used for engine condition monitoring although often acid dissolution is used to extend the range of wear metal particles which can be detected using these techniques. In one reported example of FAAS analysis of used aircraft lubricants (94/C3401) acid dissolution was used for samples containing larger wear par- ticles (up to 88 pm) and an acid mixed solvent system for samples containing smaller particles (< 10 pm). A major limitation of ICP-AES for lubricating oil analysis is the inability to measure chlorine. This often necessitates use of an alternative technique such as XRF or a combustion method in addition to ICP-AES for a full characterization of the oil. A new instrument has been described which is capable of measuring wavelengths down to 120 nm (94/C3444).This permits measurement of the chlorine line at 134.7nm which has been shown to have a detection limit below 1 pg g-' for most applications (CF> 1000 pg g-' for the visible C1 line). The ability to measure halogens simultaneously with metals and non-metals such as sulfur and phosphorus should make this instrument an extremely powerful tool for analysis of oil samples generally and lubricating oils in particular. However the robustness and long-term stability of such short wavelength lines in routine laboratory environments has yet to be estab- lished. With the exception of determination of chlorine XRF is not widely used for determination of additive elements in lubricating oils.This is largely due to poor sensitivity for magnesium one of the main additive elements. Greases on the other hand present many problems for analysis using solu- tion techniques such as AAS and ICP-AES since they can be difficult to dissolve or digest without loss of analyte. Consequently XRF is a suitable alternative since samples can be analysed directly but it is often difficult to get uniform and repeatable filling of the sample cups and out-gassing can occur during exposure to the X-ray beam giving rise to poor accuracy and precision. Seiber (95/1619) has described an elegant solu- tion to this problem in which the samples were diluted with a binder powder. The powder absorbed the oil and created a uniform particle structure which substantially improved measurement repeatability.Furthermore the method elimin- ated the problem of out-gassing and reduced matrix differences between different types of greases (type of soap varying oil content presence of graphite etc.) permitting use of liquid oil standards for calibration (analysed greases not required). 2.2. Organic Chemicals and Solvents A summary of the work concerned with analysis of organic chemicals and solvents published during the review period is given in Table 2. A review (642 refs.) of work carried out in China on the analysis of chemical industry products petro- Journal of Analytical Atomic Spectrometry December 1995 V01.10 379Rchemical industry products and silicate during the period July 1991 to June 1993 has also been published (95/67).2.2.1. Chemicals Methods for determination of most elements in virtually all types of organic chemicals are now well established and so little of the work carried out over the review period was concerned with straightforward determination of elements in specific matrices. The major challenge now appears to be the increasingly important area of determination of the chemical form of the elements present in the samples and this is where most effort has been directed during the review period. In relatively simple cases where the analyte can be present in only a very small number of forms it is often possible to carry out the chemical speciation by selective dissolution using specific reagents. For example speciation of chromium in com- post from municipal wastes has been accomplished by Tessier's method in which the elements were divided into five fractions by sequential extraction with suitable solvents (95/47).Leaching with simulated rain solution (including acid rain) was studied and CrV* was leached (2 h) from the compost using 0.1 mol 1-1 sodium hydroxide solution. Results showed that most of the Cr was present in the compost in an insoluble form and that only small amounts could pass to the environ- ment during normal use. However it was something of a concern that around 12% of the chromium was found to be present in the form of Cr". Where more specific information is required regarding the chemical form of the elements present or where the analyte can be present in a variety of different forms the most common approach is to combine chromatographic separation with some form of atomic spectrometric detector.Capillary GC exhibits very high chromatographic resolution and so this is the separation method most often used in cases where the analyte is sufficiently volatile to pass through the column (or can be made sufficiently volatile by derivatization). In view of the widespread availability of robust commercial instrumentation GC-AES has become the method of choice for a wide variety of applications. This technique can provide information on element ratios (including C H N 0 S and halogens) and empirical formulae for individual compounds separated on the column and so provides a very powerful adjunct to GC-MS for analysis of unknown compounds in a complex mixture.Calibration procedures adopted are often very simple and are easily automated (95/C2917) but these generally assume that the calibrations are independent of the chemical form of the analyte. Literature reports have shown however that this is certainly not universally true and there are many instances where the assumption is not valid. Webster and Cooke (95/1225) have shown that not only did oxygen calibration slopes vary depending on the molecular form of the analyte but also showed variation for the same compound depending on the condition of the plasma cavity discharge tube. Spurious oxygen peaks can also be generated by etching of the discharge tubes by fluorine in the plasma when fluorine compounds are analysed although it was shown that this problem could be solved by using hydrogen and methane gases to produce a carbon coating on the (alumina) discharge tube (94/3257).Another problem which has been reported with GC-AES for some applications is poor peak shape (95/2304). In this case the authors were able significantly to reduce peak splitting of high molecular mass polycyclic aromatic compounds by in tro- duction of additional make-up gas introduced through the transfer line. In spite of all of the reported problems however GC-AES still appears to have found widespread use for a number of applications particularly in com bina tion with GC-MS. A review has been published covering use of this technique combination for determination of chlorinated aro- matic compounds and phenols (95/1928). A comparative study of three different helium MIP sources a Beenakker cavity a surfatron and a microwave plasma torch (MPT) has been carried out with respect to their performance for the determi- nation of chlorinated hydrocarbons (95/1025). It was found that that the Beenakker cavity gave the best detection limits (0.05 ng ml-I for C and 0.5 ng ml-1 for C1) and for low analyte loading (e.g.when used as a GC detector) gave accurate C Cl ratios. However when analyte loading was high the MPT was markedly superior to the other sources. Where higher sensi- tivity is required MS can be used in place of AES as the detection system. Olson et al. (95/C2959) have reported appli- cation of an rf GD source (usually confined to analysis of solids) for element specific detection using GC-GD-MS.The system was tested on organotin compounds and produced detection limits in the order of 1 pg (as tin). The ICP can also be used as a source for MS detection of GC effluents and in normal operation produces almost complete fragmentation of analytes to monatomic ions-ideal for element specific detec- tion. However for characterization of unknowns it is also necessary to obtain parent molecule and fragment ions. Generally this requires a separate experiment with complemen- tary dedicated equipment using for example an electron impact (EI) source. Evans et al. (94/C3456,95/527 and 95/1464) have shown that using low-pressure ICP-MS it is possible to control molecular fragmentation and to obtain either atomic (similar to conventional ICP-MS) or molecular (similar to EI) mass spectra simply by adjusting the plasma gas flow rate and forward power.Reported limits of detection were generally in the region of tens of pg. Although at an early stage of develop- ment instrumentation of this type could prove to be extremely powerful for characterization of unknowns and may ultimately obviate the need for use of complementary techniques e.g. GC-AES and GC-MS. One problem with all of the equipment described above is that it is relatively expensive limiting widespread use and also the sensitivity often does not match that of small dedicated GC detectors [e.g. electron capture detectors (ECD) for halogens]. The solution to these problems may come with the advent of small cheap semiconductor diode lasers.Niemax et al. (95/249) have described a novel detector which has been applied for detection of halogens and oxygen using non-resonance AA of the elements excited in a dc discharge using wavelength modulated diode lasers. Preliminary detection limits reported were 0.6-1.5 ng 8-I for C1 compounds (using C1 837.6 nm line) approximately 70ng 8-l for F compounds (F 739.87nm line) and around 20 ng 8-l for 0 containing molecules (0 777.18 nm). Detectors of this type may ultimately pose a serious challenge to more established detectors such as ECD and AES for element specific GC especially since selectivity is undoubtedly mark- edly superior to many (e.g. ECD). For less volatile analytes it is not possible to use GC for separation of the chemical species without first carrying out lengthy derjvatizations to convert them into more volatile forms.For this reason it is usually preferable to use HPLC for these applications. During the review period HPLC has been used in combination with ICP-AES for determination of Cu organometallic dyes and their degradation products (95/C2932) and in combination with ICP-MS for speciation of Co and Zn protoporphyrins and hemin and application to determination of zinc protoporphyrin from the blood of a lead poisoned patient (95/1977). The HPLC-ICP-MS combination is particularly powerful in view of the high sensitivity which can be achieved (detection limits typically in the ng range) making it ideally suited to applications where the concen- trations of analyte can be extremely low (e.g.most environmen- tal applications). However it is well known that the ICP-MS sensitivity can vary enormously (sometimes as much as several hundred per cent) with changes in matrix e.g. as the solvent 380 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10composition changes in gradient HPLC or if organic compo- nents co-elute with the analyte(s) of interest. This can make calibration of the techniques very difficult and accuracy of results obtained can often be severely degraded. A solution to this problem is to calibrate using isotope dilution. Since only isotope ratio measurements are used in calculation of concen- trations using this approach and since both isotopes of the analyte in question are suppressed or enhanced to exactly the same degree by matrix changes this approach does not suffer from the matrix effect problems which can plague external calibration methods.Heumann et al. (95/529) have described a system which can be used for HPLC-ICP-ID-MS. In the case of well defined species isotope dilution was carried out by adding an isotopically enriched species specific spike to the sample solutions prior to the separation column or for species with unknown composition or structure a species unspecific spike was continuously added to the eluent. Examples of the former approach were determination of iodide and iodate in mineral water (0.5-20 ng ml-') and the latter approach deter- mination of metal complexes with humic substances (around 1 ng m1-l) and organo-iodine compounds in natural water (0.7-1.4 ng ml-I).In some cases although it may not actually be necessary to determine the different chemical forms of an element the fact that the element can be present in several different forms can severely alter the response of atomic spectrometric techniques making quantitation impossible. An example of this is determi- nation of S in aqueous samples using plasma emission spec- trometry where erroneous results can be obtained due to selective volatilization of the more volatile compounds during nebulization. Alvarado and Carnahan (94/2996) have solved this problem using a system in which the sulfur compounds were converted to hydrogen sulfide by non-catalytic pyrolysis at 1050°C in the presence of hydrogen gas trapped by condensation in a liquid nitrogen trap and then flash vaporized into a 1.6kW helium MIP for determination using AES.Results were obtained for aqueous solutions of cystein meth- ionine dimethylsulfoxide and ammonium sulfate. Detection limits were 30 ng g-' using the non-resonant S line at 921.3 nm and 0.4 ng g-' for the resonant S line at 180.73 nm. Another approach to solving the selective volatilization problem is using a direct injection nebulizer (DIN). It has been demon- strated that using a DIN it is possible to measure total organic carbon (TOC) simultaneously with other elements in water and effluent samples using ICP-AES (95/C620). Detection limits obtained were around 0.5 pg g-' although the potential exists to improve this substantially by reducing the background carbon in the plasma.It appears that even conventional nebulizers have something to offer in the field of TOC analysis. It has been shown that a glass pneumatic ICP-AES nebulizer could be used to introduce samples into combustion TOC analysers and that compared to conventional drip sample introduction the new approach gave more symmetric signals less tailing and lower noise (95/2882) Determination of heavy metals in herbal drugs and traditional Chinese medicines continues to attract a lot of attention with most papers concentrating on sample preparation techniques (e.g. 95/2252 95/2780). Jung et al. (95/915) have carried out a comparative study of three digestion methods for the determi- nation of Cd Cu and Pb in crude herbal drugs using FAAS. The most promising method was found to be autoclave diges- tion with nitric hydrochloric and perchloric acids at 105 "C and 0.4 kg cm-2 for one hour (although solutions had to be filtered prior to analysis).Other specific reports included GFAAS determination of As (95/1057) and Se (95/973) and cold vapour AAS determination of Hg (94/C3404) in tra- ditional Chinese medicines. In the latter work samples were digested using a mixture of nitric acid sulfuric acid and hydrogen peroxide and tin" chloride was used as the reducing agent for Hg". Another reducing agent which is commonly used is sodium borohydride. Gutierrez and co-workers (94/3027) have shown that with this reducing agent it is possible to enhance the sensitivity of the cold vapour AAS method by approximately 50% by adding surfactant (sodium dioctylsulfosuccinate) to the solutions.The increase was attri- buted to accumulation of Hg" ions on the anionic micelle surface by electrostatic attraction providing a better location for reduction by the sodium borohydride. Sensitivity enhance- ment has also been reported for determination of Pb by plumbane generation AAS using 1-( 2-pyridylazo)-2-naphthol- 6-sulfonic acid (94/3030) while L-cystein has been shown to be an effective replacement for the reducing agent potassium iodide for determination of As and Sb using hydride generation AAS (94/3002). L-cystein showed similar performance to pot- assium iodide but required lower acid and reagent concen- trations and had the further advantage that solutions were stable for at least 1 week (cf. 1 day for potassium iodide solutions).Indirect methods using atomic Spectrometric tech- niques for the determination of molecular compounds have been fairly extensively used for pharmaceutical applications particu- larly for Chinese medicines. The methods are generally quick and simple and require only a minimum of equipment. Examples during the review period included the determination of papaverine hydrochloride in pharmaceutical preparations by ion pair formation with ammonium reineckate (95/2517) and determination of alkaloids in Leonurus heterophilus Sweet and its pharmaceutical products by ion pair formation with Cr(MH3)2(CSN),- (94/C3410). In both cases insoluble ion pairs were formed with the analytes allowing indirect determi- nation of the analyte from the residual metal left in solution or from analysis of the precipitate.Another area which has attracted interest over the review period is the determination of trace elements in edible vegetable oils using GFAAS (94/C3406 95/409). In the latter study the method was used to measure A1 and Fe in olive and sunflower oils after storage in contact with various metals and alloys. The possible effects of metal contamination on oxidative stability were also discussed. The IUPAC Commission on Oils Fats and Derivatives has carried out development and evalu- ation of a direct GFAAS method for determination of Pb in edible oils and fats. The method which involves heating the sample to 60"C shaking to homogenize and mixing with 2% lecithin solution in cyclohexane has been tested in a round- robin study involving 23 collaborators from 12 countries using various graphite furnaces with and without platform.Reproducibility and repeatability RSDs were 30.2 and 11.3% respectively for soya bean oil and 29.7 and 7.0% respectively for cocoa butter. The method has been adopted first action by AOAC International as an IUPAC-AOCS-AOAC method. One difficulty which can be encountered with analysis of edible oils and fats is that elements can often be present in the samples in the form of catalyst fines (particle sizes typically 0.5 to 50 pm) making it difficult to automate the analytical method. Van Dalen and de Galan (95/222) have circumvented this problem by using an ultrasonic slurry sampler for fully automated determination of particulate Fe and Ni in edible oils and fats.The system comprised a heating mat for the autosampler tray which was used to heat the samples (held in 2.5 ml polyethylene cups) to 60 & 5 "C and a titanium sonic- ation probe operating at a power of 10 W which was placed 5 mm above the bottom of the sample cup to be analysed and held for 20s to homogenize the sample prior to sampling. Results obtained using the automated system were found to give good agreement with the standard IUPAC method in which samples were manually stirred prior to sampling using a micropipette. The determination of trace impurities in organonetallic reagents and process chemicals used for production of semicon- Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 381 Rductor devices by metal organic chemical vapour deposition (MOCVD) continues to become ever more demanding as increasing device density places increasingly stringent limits on tolerable levels of contaminants in the deposited films.Analysis of these reagents is one of the most challenging tasks facing the industrial atomic spectroscopist since they are frequently unstable often pyrophoric and can contain impurit- ies in both volatile and non-volatile forms. Argentine et al. (95/299 95/532 and 95/1912) have described an elegant solu- tion to this problem using electrothermal vaporization induc- tively coupled plasma spectrometry (AES and MS). The ETV was placed inside an argon purged glove box and was adapted to permit initial sub-ambient temperatures in order to facilitate handling of the volatile air sensitive materials.Temperature programming of the ETV permitted separation of the volatile impurities (Ga Si Sn and Zn) from the non-volatile impurities (Al Ca Cd Cr Cu Fe Ga In Mg Mn Ni Pb Si Sn and Zn) although measurement of the volatile impurities was only semi-quantitative due to difficulties with calibration and matrix effects caused by concurrent matrix evaporation. The method was applied to analysis of trimethylaluminium trimethylind- ium phosphorus tribromide and phosphorus oxychloride. Determination of trace elements in a photoresist solution by MIP-MS has also been reported (94/3188). Solutions were diluted tenfold with 2-ethoxyethylacetate prior to direct intro- duction to an oxygen-nitrogen MIP for determination of Cr Cu Fe Mn Ni and Pb using mass spectrometry.Detec- tion limits ranged from 0.01 ng ml-' (for Cr and Mn) to 0.10 ng ml-I (for Cu). 2.2.2 Solvents As in previous years the complex mechanisms responsible for solvent eflects in inductiuely coupled plasmas have continued to provide a challenging area for research. Weir and Blades (95/525 and 95/526) have studied the effects of solvent (water methanol and chloroform) and solvent load on the background spectra and visual features of the ICP and on the axial emission profiles of Mg I Mg 11 C C and CN. The authors have also described a method for obtaining spatially resolved maps of electron density from the intensity of one argon line using numerical asymmetric Abel inversion (95/2188). The measure- ments were calibrated by comparing with electron density measurements obtained from Stark broadening measurements of the H p line and then used to obtain time-averaged electron density maps covering virtually the entire volume of the plasma (5 to 25 mm downstream of the induction coil and & 8 mm from the axis).The electron density maps revealed significant differences in solvent distribution between different classes of solvents with oxygen free solvents (e.g. chloroform) being confined to the aerosol channel whereas oxygen containing solvents (e.g. methanol) were found to be distributed over the outer argon streams. The mechanism responsible for this effect is not clear but the inner argon flow rate was found to influence the distribution of solvent load between the axial channel and the outer argon stream and hence to influence the response of electron density to solvent load.The authors also postulated that electron density information obtained from argon line intensity measurements could potentially be used for control diagnostics. The effect of ethanol loading on electron density hydrogen distribution excitation temperature and analytical parameters of an ICP has been studied by McCrindle and Rademeyer (95/293 and 95/2399). The intensity of the H CI line and the electron density were both found to increase with increasing ethanol concentrations as did the mass flow rate of aerosol (mean drop size increased from 2pm for water to greater than 4.5 pm for 25% ethanol). The excitation tempera- ture (determined from hydrogen emission) was found to increase with increasing ethanol concentrations up to a maxi- mum at 15% v/v ethanol after which further increase in ethanol concentration caused a decrease in excitation temperature. Sensitivity detection limits and background equivalent concen- trations for Al Cd Cr Fe Mn Mo Na Pb and V were found to be correlated with the excitation with optimal detection limits being obtained when the samples were in 15% v/v ethanol solutions.The carrier gas flow rate was more critical for ethanol solutions however than for pure water (possibly owing to its effect on distribution of solvent loading within the plasma). Although in some cases introduction of organic solvents to ICPs can have a beneficial effect on analytical performance (as in the example above) very often this is not the case particularly with volatile solvents where high organic vapour load can destabilize the plasma (sometimes to the point of extinction) and can severely degrade analytical performance owing to solvent related spectral interferences.Botto and Zhu (94/3250) have shown that using an ultrasonic nebulizer with a membrane desolvator it is possible to analyse volatile solvents (boiling points below 100 "C) by ICP-AES using conventional sample introduction rates (1-4 ml min-') and to obtain analyt- ical performance comparable to that for aqueous samples. Since virtually all of the solvent was removed from the aerosol prior to introduction into the plasma the authors also showed that in some cases it was possible to use 'universal' solvent independent calibrations (after correcting for solvent nebuliz- ation efficiencies).This could prove to be useful for the small number of cases where it is difficult to prepare calibration standards in the same matrix as the samples although selective volatilization of volatile analyte could still be a problem (e.g. for light petroleum fractions). As with ICP techniques organic solvents can also have a significant effect on FAAS absorbances. In some cases this can be used to advantage for example Malla et al. (95/1924) have reported a significant enhancement in V sensitivity for FAAS using an air-acetylene flame when 20% propanol was added to solutions prepared in 0.5 mol 1-' hydrochloric acid. However in most cases changes in FAAS absorbance caused by the presence of organic solvents is more of a problem since this can make calibration difficult especially if the concen- trations of solvents in the samples are unknown and/or vari- able which can make matrix matching of calibration standards impossible.For FAAS determination of Ru in hydroformulation solutions for example Kaupinnen and Smolander (95/1839) found that varying concentrations of toluene in the sample solutions or the presence of other organic substances such as hexene heptanol and heptanal even at concentrations of only a few per cent. had a significant effect on FAAS absorbances. The authors reported that by diluting the samples at least ten- fold with ethanol the concentration of the other organic substances was reduced to less than 1% total and at optimum burner height the interference effects became insignificant.Dilution with IBMK was also tried but ethanol was preferred since it is cheaper smells less unpleasant kept the burner and chamber assembly cleaner and provided slightly better sensi- tivity. The authors also carried out a similar study for determi- nation of Rh organic solutions (94/3127). In this case the recovery for a 5 pg g-' Rh standard was only 60% when the solution contained 5% hex-1-ene but improved as the ratio of aldehyde or alcohol to hexene increased. Thus for toluene solutions containing not more than 10% hex-1-ene plus 10% heptan-1-01 heptan-1-a1 or their mixtures it was found that the matrix effects could be compensated by adding 20% heptan-1-a1 as buffering agent and 70% ethanol as solvent. Extraction into organic solvents using metal chelating agents is one of the most commonly applied techniques for analyte preconcentration and matrix removal.Solvents with a low solubility in water e.g. carbon tetrachloride chloroform and dichloromethane can permit large concentration factors through use of high aqueous to organic volume ratios. 382 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10However if sample size is limited the resulting volume of organic solution can be small making direct nebulization techniques such as FAAS unsuitable without further dilution of the sample. A system has been described in which small volumes of sample (< 60 ml) were injected into a small PTFE funnel coupled directly to the nebulizer needle allowing dis- crete nebulization of single drops of extract solution into an FAAS spectrometer (95/304).Signal profiles were compared for a number of elements extracted into chlorinated hydro- carbon solvents using several complexing agents and ion- pairing compounds using both nitrous oxide-acetylene and air-acetylene flames. The composition of the solvation sphere (ligands and counter ions) around ions in solution is an area which has rarely concerned atomic spectroscopists primarily owing to the lim- ited availability of techniques which can address this area. A promising new technique for these applications is electrospray mass spectrometry. Agnes and Horlick (95/3065) have shown that by adjusting instrument parameters (principally curtain gas flow rate and sampling plate voltage bias) it was possible to observe either solvent-ion clusters [e.g.M( MeOH) ] or bare singly charged analyte ions (M'). Thus the technique could be used to provide elemental analysis or to provide information on molecular form valence state or solvation sphere (for both cations or anions). This is a good example of the continuing trend towards analytical instrumentation fulfil- ling multiple analytical functions and of the increasingly fuzzy boundaries between atomic and molecular mass spectrometry (see also 2.4 Inorganic Chemicals) 2.3. Catalysts Specific methods for analysis of catalyst samples which have been published during the review period include digestion of borosilicate catalysts for ICP-AES analysis by fusion with potassium hydroxide (95/89 1 ) determination of trace elements in aluminosilicate based catalysts by FAAS after digestion with hydrofluoric nitric and sulfuric acids (95/1216) and pressure decomposition with nitric and hydrochloric acids of hydrogen- ation catalysts comprising Ag Pd and Na on aluminium supports (95/1904).Most of these methods are based on application of fairly standard digestion techniques followed by routine determinations using ICP-AES or FAAS. One appli- cation which was slightly different was the determination of Pt and Rh in cobalt oxide catalysts using FAAS (95/3103). Samples were reduced by heating for 3 h at 650 "C in a stream of hydrogen at a flow rate of 5 1 h - l prior to digestion in aqua regia evaporation and final dissolution in 2 mol 1-' hydrochloric acid. Platinum was determined after extraction into IBMK using triphenylphosphine.Although the determination of total concentrations of active metals and poisons in catalysts provides valuable information especially for quality control commercial settlements and troubleshooting purposes on its own this information is rarely sufficient for catalyst characterization purposes. The distri- bution of active metals and poisons over the surface of the support materials is also an important parameter influencing catalyst performance and laser ablation ICP-MS has been shown to be a useful tool for this application (95/C483) although only for applications which do not require spatial resolutions better than a few pm. In order to understand fully the role of the active metals and their influence on catalyst performance however it is generally necessary to apply several analytical techniques in combination.This approach was adopted by Bodnar et al. (95/1160) who utilized X-ray photo- electron spectroscopy X-ray diffraction electrochemistry and atomic emission spectrometry to study the role of a Ge promoter in a palladium-carbon hydrogenation catalyst. The Ge was found to be deposited exclusively on the Pd particles and to be present in one of two distinct forms. At a Ge Pd atomic ratio of up to 0.6 the germanium was found to be present exclusively in the strongly adsorbed Ge (n') form whereas at higher promoter palladium ratios bulk alloy (Ge 0) was also observed. The role of the latter in the hydrogenation mechan- ism for various reducible functional groups and unsaturated carbon-carbon bonds was also discussed.Multiple analytical techniques have also been used to characterize polymer sup- ported colloidal palladium catalysts prepared by a novel one- step process (95/2773). The colloidal catalysts were prepared directly from monomers and metallic precursor in one step. X-ray photoelectron spectroscopy transmission electron microscopy SEM electron diffraction IR ICP-AES and pho- tomicroscopy were used to characterize the catalyst structure and metal dispersion and to study the influence of preparation conditions. Results showed that the Pd particles were ultrafine highly dispersed and distributed uniformly throughout the polymer support. Similarly X-ray diffraction electron spin resonance and AAS were used to determine the crystal struc- ture Ti oxidation state and concentrations of Al Mg and Ti in titanium tetrachloride-silica polyolefin catalysts modified with magnesium chloride (various Mg Ti ratios).The catalysts were used to prepare homo- and copolymers of ethylene and propylene using Al(i-C4H9)2 as co-catalyst and the results of the polymerization correlated with the analytical data. 2.4. Inorganic Chemicals and Acids Although significant improvements in the sensitivity in atomic spectrometric techniques have been achieved over the last decade there is a recognition that in many 'real world' laboratory situations detection limits are primarily constrained by analytical blanks arising from impurities in reagents and as a result of environmental contamination.The development of sample preparation methodology which addresses this type of problem has been discussed in a recent conference presentation (95/C2088). A sub-boiling distillation unit made entirely from PTFE was used for the transformation of acids and other liquids into high-purity reagents. The device was also reported to provide improvements in the efficiency of liquid throughput in comparison with other systems. It was also recommended that analytically clean areas within a laboratory could be restricted to dedicated cabinets with favourable surface and material properties and a supply of filtered clean air in order to minimize expense without compromising performance. The design of a sample preparation device for acid dissolution was described. This consisted of a simultaneous pressure decompo- sition unit combined with a low pressure acid evaporation and neutralization unit.Environmental contamination was mini- mized by direct exhaustion and neutralization of acids fumes and this was also shown to reduce acid consumption and corrosion within the laboratory. The system was able to handle a series of 16 or 32 solid samples without cross-contamination due to the use of PTFE vials. An apparatus for the isolation of metal impurities from liquid samples was described in a recent patent application (95/856). The sample which could be acid or alkaline was placed in a wide-mouthed container. A second container holding either an acid or a base which could neutralize the sample was then prepared. Both were placed in an a larger acid- and base-resistant air-tight container.The sample was neutralized by the vapour of the volatile acid or base and was then passed through a column containing a chelating resin to concentrate the metal impurities. It was reported that the system could be used to achieve high accuracy by avoiding contamination although no details of the measure- ments made were provided in the abstract. The need to reduce reagent blanks is in part an indicator of the growing industrial requirement for high purity acids and chemicals and the consequent need to have quality control Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 383 Rprocedures to support raw material and product specifications. Inductively coupled plasma mass spectrometry is particularly suited to this type of application because sensitivity in the pg g-' range can now be achieved for the majority of elements.Nevertheless for samples containing sulfuric or hydrofluoric acid it is often necessary to dilute the sample prior to measurement by ICP-MS because of the corrosive effects on the sampler and skimmer cones and contamination arising in the sample introduction system itself. As a result a preliminary preparation step to preconcentrate the sample may still be required to achieve adequate sensitivity and such a process may take several hours. A sample preparation method for the determination of B in sulfuric acid by ICP-MS may be of some interest in this context (95/1298). Methanol was added to the acid sample and an inert gas was bubbled through the heated solution.The trimethylboric acid thus formed was distilled and passed into an aqueous solution of a resin containing at least two adjacent alcohol functional groups in a repetition unit to collect the analyte. Boron was then eluted with acid and detected by ICP-MS. It was reported that B could be detected in high-purity sulfuric acid at levels as low as 0.1 ng g-l using this method. The determination of trace metal impurities in hydrojuoric acid has been carried out using ICP-MS and isotope dilution mass spectrometry (95/2440). A rapid method of sample evapor- ation (up to 200 ml h-') was employed which minimized metal contamination. A comparison was made of the performance of ICP-MS using both isotope dilution and external calibration measurement strategies with IDMS using a thermal ionization source. It was found that if the evaporation procedure was used all three methods gave accurate results for the determi- nation of Ag Cd Cr Cu Ni Pb Th T1 U and Zn in high- purity hydrofluoric acid.Detection limits were reported for these elements in the pg 8-l range. However the TIMS system was significantly better than ICP-MS for the determination of Fe at concentrations below 100 ng 8-l. An alternative approach based on the use of a direct injection nebulizer was described which was reported to overcome such problems (95/C635). The device was used in conjunction with a rapid preconcentration technique claimed to be virtually free of contamination and which achieved superior spike recoveries for the determination of metal impurities at low pg 8-l and sub-pg 8-l levels in ultra pure water hydrofluoric acid and ammonium hydroxide.The application of direct injection nebul- ization in ICP-MS to the analysis of semiconductor grade nitric and hydrofluoric acids and hydrogen peroxide process reagents has also been described (95/C786). It was reported that the direct injection nebulizer was able to introduce 100% of the sample cleanly to enable multi-element analysis at a flow rate of only 50 p1 min-l. Electrothermal uaporization may also be used to introduce microsamples into the ICP-MS while providing an improve- ment in detection limit as a result of improved transport efficiency. The effect of mineral acids on ETV-ICP-MS signals was the subject of a detailed study (94/3252).The behaviour of analyte signals for Co Cu Ag Cs Pb Bi and U was examined under compromise multi-element conditions in the presence of a range of concentrations of hydrochloric nitric phosphoric and sulfuric acids. The use of a pyrolysis step (400°C) in the ETV heating cycle was reported to be effective in completely volatilizing nitric acid from the graphite surface but a small amount of chloride (40 ng) was retained under these conditions following the injection of 10 p1 of a 1% v/v hydrochloric acid solution. It was found that analyte signals were enhanced by as much as a factor of two in the presence of 1% v/v nitric and sulfuric acids but that phosphoric acid caused suppressions in the responses for Ag and Bi. The addition of a mixed chemical modifier was reported to have a beneficial effect by reducing or removing the interferences from these acids.The determination of Si in acids used in the semiconductor industry is important because insoluble silica compounds can be left on the surface of the wafer during processing and can form particles which cause device failure. However there are few atomic spectrometric techniques which can be applied to the detection of Si at sub-ng g-' levels. The development of a method based on ETAAS was the subject of a recent conference presentation (95/C3032). An investigation identified graphite purity and contamination of reagents and from the environment as major problems in the determination. The same workers have also used ETAAS for the analysis of hydrogen peroxide and phosphoric acid (95/C3030).A method of evaporating hydrogen peroxide using a dynamic vacuum was reported to allow concentration of the reagent without the risk of spontaneous decomposition. Interferences were observed in the determination of K and Na in phosphoric acid. It was reported that signal suppressions could be over- come by optimization of the furnace temperature programme and the use of a standard additions approach. Most atomic spectrometric techniques are not widely used for the analysis of gases primarily because commercial instru- mentation is designed specifically for the examination of solid and liquid samples. Indirect ICP-AES methods involving extraction/absorption procedures for example in the analysis of hydrogen sulfide (95/1906) and the determination of trace elements in hydrogen chloride gas (95/C621) have been reported in the year under review.However most AA and AE sources can be adapted to the direct analysis of gases if appropriate methods of vapour handling sample introduction and response calibration can be devised. This task is perhaps most challenging when dealing with the analysis of reactive acid process gases such as are commonly encountered in the semiconductor industry. An instrument has been described for the direct determination of Fe in hydrogen chloride gas by ETAAS (94/3246). A modified by-pass-backflush-balancing gas injection system was employed for the contamination-free sampling of gaseous hydrogen chloride (see Schramm Gas Aktuell 1992 43 26). All the components of this system were made from non-metallic materials such as polypropylene PTFE and glass.A specially designed graphite capillary was used as the gas inlet to the ETA and it was possible to control the volume of gas introduced to the atomizer. Calibration of analyte response was achieved using Fe standard solutions. A detection limit of 0.7 ng ml-' Fe was reported at the optimum temperature conditions established. The reproducibility of the method for the measurement of Fe in hydrogen chloride was 4%. The same sampling system was also used in conjunction with an MIP-AES system for the latter determination (94/3260). Calibration was achieved using a certified gas reference sample containing iron pentacarbonyl in argon. A detection limit of 0.25 ng ml-' Fe was reported with a relative precision of 6% (n = 10) for the determination of Fe in hydrogen chloride gas.An alternative approach to this problem involving the use of a sealed ICP source has been pursued by Jacksier and Barnes (95/329). The plasma which could be operated at flow rates as low as 70 ml min-' was sustained in argon. Anhydrous hydrogen chloride gas was introduced to the plasma and chlorine was added as a modifier gas in a ratio of 1 1 to maintain stable and reproducible AES signals. Calibration for the quantitative determination of C and Sn was achieved by vapour phase sampling of monobutyl tin chloride as a standard. Detection limits for C and Sn were reported as 271 and 49 ng g-' respectively in a 16% hydrogen chloride-chlorine-argon plasma. Several elements including Al Ca Cr Fe and Ni and were also identified qualitatively using this system.The system was also applied to the direct analysis of electronic grade chlorine gas (95/2185). In this case a pure chlorine discharge was sustained at an applied rf power of 1 kW in the non-flowing mode. The energy of the static 384 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10discharge was found to be greater than that of the flowing system. Ten elements (Al C Ca Cr Cu Fe Mg Mo Ni and Sn) were detected and quantitative calibration was established for the determination of C and Sn by doping the chlorine stream with these elements. Under flowing source condi- tions detection limits for C and Sn were 725 and 25 ng g-' respectively. Most techniques commonly employed for the analysis of metal salts are subject to some form of matrix interference.Methods for matrix removal and analyte preconcentration for flame spectrometry are well established in the literature. However in a variation on this theme a flowing system for on-line preconcentration has been used for the indirect determi- nation of carbonate oxalate or dichromate by FAAS (95/2551). Sample solutions were mixed in a coil with silver nitrate and pumped to a precipitating loop where precipitation was allowed to occur for 2min. The dissolving agent (either ammonia perchloric acid or phosphoric acid) was passed through the system and the anion was determined indirectly as Ag. The relative precision of the method was reported to be in the range 1 to 1.3%. Papers on the separation of Sr from Ca by anion exchange (95/2858) and the extraction of Cu Co and Ni from lithium salts (95/2834) may also be of some interest.Welz and Luecke (94/3349) have re-visited the inter- ference of aluminium chloride and nitrate on the alkaline earth elements in an air-acetylene flame. It was found that particle size was the decisive factor influencing sensitivity and that any species which inhibited the conversion of chloride into oxide (e.g. hydrogen chloride or caesium chloride) counter-acted the suppressing effect of the aluminium matrix. Acid leaching has been used to avoid interference effects in the ETAAS determination of trace elements in aluminium fluoride (95/2329). It was shown that nitric acid could be used to leach Co Cu Fe and Ni quantitatively from the insoluble bulk matrix thus obviating the need for time-consuming solvent extraction procedures.The results obtained were in good agreement with those achieved using SS MS. Solid-phase extraction has been applied to the determination of analytical- reagent grade sodium salts using FAAS ETAAS and ICP-AES (94/3001). Trace amounts of Cd Co Cr Cu Fe Hg Mn Ni and Pb were preconcentrated using APDC mixed with polyure- thane foam and packed into disposable syringes. The dithio- carbamate complexes formed were extracted into IBMK or nitric acid prior to determination by the appropriate tech- nique. Except for Cr elemental recoveries were reported to be > 98%. The preconcentration of ultra-trace elements from salt solutions can also be achieved using constant current elec- trodeposition (95/1876).The elements of interest (Cd Co Cu Fe Mn Ni Pb) were electrodeposited over a period of 1-2 h onto a graphite-tube cathode from highly concentrated ammonium fluoride solutions. A recrystallized solid ultra-high purity product with an impurity level in the low pg ml-' range was obtained. The element concentrations at the ng ml-' and pg ml-' level were determined using a direct ETAAS method for ammonium fluoride solutions up to 20% m/m. Solid sampling methods for ETAAS continue to be reported. These included the direct determination of trace impurities in tantalum pentoxide (94/3147) and the detection of lithium in molybdenum oxide by slurry sampling (94/3 139). X-ray Jluorescence spectrometry is a much undervalued technique for the examination of inorganic chemicals.Whilst the technique is often associated with the analysis of solids it also offers a complementary method of estimating the composi- tion of liquids such as salt solutions (95/15). In the latter instance the sample was poured into a sample cup with a supporting film and the solution analysed directly without the need for further preparation. It was reported that by using the UniQuant semi-quantitative software package major minor and trace constituents could be determined rapidly without the need for external calibration. The lower limit of detection reported was of the order of 50 pg g-'. It is also possible to use XRF on-line for the real-time analysis of Jlowing liquid streams (95/1740). An ASOMA portable energy-dispersive system with a radioisotope source (either "Fe or 244Cm) was modified to allow operation with a flow-through cell fitted with a polypropylene window for measurement purposes.The determination of As Cu and S in purification solutions from an electrolytic cell was carried out successfully without dilution. Correction was made for interference resulting from matrix absorption of Cu fluorescence by sulfur. A detection limit of 0.7 g I-' Cu in the presence of 0.8 g 1-' nickel was reported. The chemical environment of the analyte has an important effect on the observed X-ray intensity and a number of abstracts contain information on spectral features of inorganic com- pounds. A new approach has been proposed to overcome the problem of spectral interference resulting from line overlaps in XRF by using excitation at two different energies (95/1051).X-rays from a tungsten tube were scattered in molybdenum and tin foils to produce mono-energetic beams which impinged on the sample. The resultant fluorescence was detected using an energy-dispersive instrument with a resolution of 106 eV. The samples contained As Mn Pb and Y as oxides and measurements were made over a set of 14 materials of different composition and concentrations. It was found that the concen- tration of elements with overlapped lines could be calculated accurately using this approach. A comparison of XRF intensit- ies from metals and their oxides may also be of interest in this context (95/1052). A number of abstracts have been received concerning studies of the X-ray emission lines of metal com- pounds.The spectral line profiles of the major elemental components were examined for differences in intensity width and shape which correlated with chemical state information on Ag bromide chromate sulfate and sulfide (95/1763) Cu oxides and halides (95/1604) Co and Fe ligand complexes (95/1688) and Sr compounds (95/1764). The determination of chemical state has also been the subject of study using electrospray mass spectrometry (95/1460 95/1461). Preliminary studies of the use of the technique have indicated that quantitative measurement of both elemental and molecular inorganic ions could be achieved. It was shown that linear calibration could be achieved for trace elements if the analyte signal was ratioed to the signal from a constant amount of a similarly charged electrolytic species (95/1460). The dynamic range of the method was reported to be linear over at least four orders of magnitude.When the electrospray source was operated under low-voltage or 'mild' conditions it was possible to detect complex metal ion clusters [e.g. of the type Co(MeOH),+ 1 and potentially the solution valence state of cations (95/1461). The operation of the electrospray source in the negative ion mode afforded the ability to detect elemental and molecular anions. Although it is likely that the electrospray processes described in these ground-breaking papers will be highly sensitive to matrix effects there can be little doubt that a new and exciting area of research has emerged in the highly active field of chemical speciation.The application of thermal lensing to trace element speciation has also been described (95/1913). The technique was applied to the determination of copper in hydrous iron oxides but there was little practical information provided in the abstract. 2.5. Nuclear Materials It has been established for many years that spectral interferences cause significant problems in the analysis of uranium compounds by ICP-AES. The publication of a survey of uranium lines in the wavelength range 235-500 nm will be of particular interest therefore to workers in the nuclear industry (95/1534). The data and text files containing information on 8361 uranium Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 385Rlines were reported to be available on disk in a format suitable for an IBM compatible personal computer.Most of the abstracts received concerning the use of ICP-MS in the analysis of uranium oxides are devoted to the application of matrix separation techniques to minimize the effect of spectral inter- ferences and improve detection limits. It would appear that the use oftributyl phosphate as an extraction agent is becoming increasingly popular for this type of separation. A method has been proposed for the determination of 18 elements (Al Ag B Ba Ca Cd Co Cr Cu Fe Mg Mn Mo Ni Pb V Zn and Zr) indicating the versatility of the approach (95/1911). The reagent has been used in the solution phase in carbon tetrachloride for the detection of 11 elements in a uranium matrix (95/895) and in dodecane for the separation and measurement of U-233 in alloy fuel (95/2812).Tributyl phos- phate has also been used for extraction in column chromatogra- phy on PTFE powder for the determination of 11 elements in uranium dioxide powder (95/107) and with Levexrel resin for the quantification of trace Ta in uranium compounds using an axial ICP-AES system (95/289) and alkali metals in uranium dioxide by FAAS/FES (95/290). A column chromatography method using Chelex 100 for the preconcentration of trace elements from high-purity uranium and thorium has also been published (95/890). However there is no doubt that ICP-MS is becoming the technique of choice for the analysis of nuclear materials. The separation of analytes from major components of the sample matrix results in significant improvements in analytical per- formance as in ICP-AES but with the benefits of superior detection limits which ICP-MS detection provides.An example of this approach has been described in the development of an HPLC-ICP-MS method for the determination of REEs in uranium materials (95/C484). The chromatographic procedure was developed to elute uranium first. Using a valve after the column it was possible to lead the uranium fraction to waste and then to redirect the analyte to the ICP-MS. This approach allowed the analysis of highly concentrated uranium solutions and avoided matrix suppression of the signal and uranium deposition on the ICP-MS sampling cones. The method was used to achieve separation of REEs and permitted the direct determination of Nd isotopes.High pressure ion chromatogra- phy has been used in ICP-MS for the removal of isobaric interferences (95/C8 17). A gradient separation using oxalic- diglycolic acid with a cation/anion column was used to remove light rare earth oxide interferences on heavier REEs while also enabling the determination of their non-natural isotopic abun- dances. The method was applied to the detection of REEs and actinides in spent uranium dioxide fuel. In a separate appli- cation described in the same paper an anion column in-line with an anionic membrane suppressor was used for the determi- nation of 1-129 in simulated tank wastes in the presence of xenon. A further procedure utilizing a hydrochloric acid separa- tion gradient was used to overcome isobaric interferences in ICP-MS on Io7Pd from silver Sr from yttrium and zirconium and on 99Tc from ruthenium.The use of ion chromatography for the alleviation of isobaric interferences in ICP-MS was taken a stage further by the use of isotope dilution (95/2397). An Elan 5000 ICP-MS modified for operation in a glove box was combined with a Dionex ion chromatography system comprising an HPLC pump a CG2 guard column a six way high pressure valve and an analytical separation column. The outlet from the separation column was passed to the cross flow nebulizer of the ICP-MS. A 200 pl sample loop was used for all measurements and helium gas was used for de-gassing the eluents and to activate the injection valve from the HPLC pump automatically. Chromatographic methods employing ID-ICP-MS were developed for the separation of fission Cs from naturally occurring barium for the separation of lantha- nides and for the determination of Pu in the presence of actinides.Methods for matrix removal using ion-exchange resins prior to mass spectrometry may also be of some interest. These include the determination of Dy in uranium oxide by isotope dilution MS (94/3204) the separation of the major components in gadolinium oxide-uranium oxide pellets prior to detection by TIMS using isotope dilution (95/2578) and a study of the affinity of the Np-type chelate resin for the matrix element in the isotope analysis of solid uranium by MS (95/1265). Although ICP-MS is normally employed to take advantage of the high sensitivity afforded for ultra-trace levels analysis in nuclear applications the determination of major isotope content of samples is also important.A multiple collector magnetic sector ICP-MS system has been utilized for the determination of isotope ratios in IRMM 072 synthetic uranium mixtures (95/C2078,95/2398). The linearity and mass discrimi- nation exhibited by the instrument were studied and modelled using power law and exponential functions to correct for these effects. It was reported that the observed isotope ratios for U did not differ significantly from the certified values after correction. A study of the accuracy and precision of ICP-MS in the determination of major elements in nuclear samples has been carried out (95/C470). The correction of mass bias and detector dead time losses was achieved by use of isotopic reference materials for the actinides. It was observed that the day to day variation in mass discrimination in the ICP-MS instrument used was not significant.The use of isotope dilution was used to improve measurement precision for the determi- nation of Pu U and Zr in alloys containing these elements and Gd in natural and irradiated uranium oxide. A standard additions approach was utilized for the determination of Np in experimental fuels and alloys. Precision obtained for the ICP-MS methods was reported to be comparable to that achieved by classical titration techniques. The characterization of nuclear waste material requires not only the quantification of levels of major elements and measurement of isotope ratios but also the identification of chemical structure (94/C348 1 95/C686 95/C815).These papers concern the use of EXAFS and near-edge EXAFS for the determination of chemical species within solid waste materials from the Hanford site. The studies showed that U and Pu in such samples existed almost exclusively as dioxides and that Sr existed in several (e.g. carbonate nitrate phosphate or sulfate) forms. A portable field MS instrument has been described for the analysis of actinides (95/C3037). 'The system based on a commercial quadrupole analyser was developed for the determination of isotope ratios in solid compounds of plutonium and uranium. Samples were volatilized in the form of volatile hexafluorides using chlorine trifluoride. Although ICP-MS is known to suffer from poly- atomic interferences it is generally assumed that the actinide elements are relatively free from this source of error.A paper on the interference of uranium and thorium hydrides on minor actinide isotopes may be of some interest (95/315). 3. ADVANCED MATERIALS This section of the Update is devoted to progress made in the characterization of advanced materials including polymers semiconductors glasses and ceramics. Applications are summa- rized in Table3 and the principal areas of development to appear during the period covered by this review are described in detail in the text below. 3.1. Polymeric Materials and Composites It is not widely recognized outside of the polymer industry that additives are used to obtain the physical properties of many materials in everyday use.For example to prevent degradation poly(viny1 chloride) (PVC) bottles are stabilized using organo-tin compounds. Where polymeric composite mate- 386R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10TABLE 3 SUMMARY OF ANALYSES OF ADVANCED MATERIALS Technique; atomization; analyte form* Reference 9511 090 9512747 9512707 95/2742 9512747 9512762 951275 1 9512234 95/C83 3 9511721 9511788 9511823 9511088 9512646 951430 9512760 9512741 95lC480 951341 9413327 95/73 95/c752 9511343 9511045 387 R Element Matrix Sample treatment/comments POLYMERIC MATERIALS AND COMPOSKES- A1 C Cd Cr F Fe N Na P Pb Pb Pb Pt Si Sn Sn Ti U Transition metals Various Various (4) Packaging materials AA;ETA;L Study of contribution to dietary aluminium from food packaging materials and cooking utensils coated with PTFE Study of fluorocarbon films deposited on glass low carbon steel and aluminium foil substrates by estimating distribution of C-F binding states Certification of Cd content of polypropylene reference standards in the range 40-400 mg kg-' The removal of matrix effects in the determination of Cr was achieved by UV photolysis in the presence of hydrogen peroxide As for C The sample was dissolved in benzene and the Fe extracted with 3 mol 1- ' hydrochloric acid Study of adhesion of thin aluminium coatings to isotactic polypropylene films using nitrogen or ammonia plasma treatment; uptake of nitrogen by the film monitored by AES and SIMS Interlaboratory trial using a variety of methods for the determination of sodium in the range 0.11 to 2.4 pg rnp3 Direct determination of P in polymers using solid sampling or dissolution procedures followed by laser-excited AFS; good agreement was obtained with ETAAS and ICP-MS methods Evaluation of portable XRF system for accuracy and precision in the determination of Pb in paint Direct estimation of Pb content of US bank notes between 1980 and 1990 to assess health risk from ink dryers Standards were prepared by mixing pulp with boric acid neutralizing mixing with poly(viny1 acetate) adhesive and solvent evaporation nanoparticles; comparison with HPLC method polymer by size exclusion chromatography using THF or xylene as the mobile phase and detection of Si in eluate by I C P LOD = 5 ng Si Measurement of methytin stabilisers leached from PVC bottles into corn oil food simulant using platform atomization with matrix modification; recovery of 15 ng g-' spike was 8% and the LOD=7 ng g-' Measurement of Sn in copolymers of tributyltin methacrylate used in self-polishing anti-fouling paints On-line mineralization of soap in a microwave oven- flow injection analytical system using sulfuric and nitric acids in a 1 3 ratio and detection of titanium dioxide filler by AAS detection limit of 3 fg uptake by wools and interactions using FTIR with principal component analysis inorganic additives using novel sliding spark source (see also 9512511) and Ti were determined as oxides using paraffin as the matrix for the preparation of calibration standards; LODs were reported in the range 0.8 to 4.8 mg g-' electrothermal vaporization in AAS or ICP-MS; analysis of dissolved fibre sample by ICP-MS using direct injection nebuliser Comparison of methods for the characterization of electronic materials including XRF and NAA Overview of the use of XRF for the non-destructive analysis of pigments used in artist's paint Detection of cisplatin loading of polymeric Separation of non-polar high molecular mass Use of electrothermal vaporization to achieve a Study of metal ion (Cr"' Cu" Fe" Ni" and Zn") Identification of C1-containing polymers and The sample was pressed into pellets and Al Fe Mg Solid sampling of individual fibres using Fluorocarbon thin films XPS Polyethylene Leather IDMS AA;F;L XPS AE;ICP;L AE;-;G Fluorocarbon thin films Poly(propy1ene oxide) Metallized polypropylene films Polyacrylate absorbent dust AA or AE;F;L Polymers AF;ETA;S or L Paint Paper XRF;-;S X R F;- S Pulp XRF;-;S AE1CP;L AE;ICP;L Polyalk ylcyanoacrylate Poly(methy1 siloxane) Food simulant extracts from PVC A A; ETA;L Organotin acrylic copolymers AA;F;L Soap AA;ETA;L Plastic Wool MS;ICP;S AE;ICP;L Poly(viny1 chloride) AE;spark;S XRF;-;S Plastics Various Carpet fibre AA or MS;ETA or 1CP;S or L Various (16) Polyimide Various Paint MS;ICP;- XRF;-;S Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 3 (continued) Technique; atomization; analyte form* Sample treatment/comments Reference 9511670 9511683 9511778 9511849 95/C2086 9512511 95lC2949 95/c3007 951c3014 Element Matrix Various Polymers MS;ICP;L or S Comparison of methods for polymer analysis involving microwave acid digestion laser ablation ICP-MS and NAA; LOD's of the order of 1 mg kg-l reported using trace element profile additives using a spectrometer configured for light element detection to minimize analysis time for quality control Application of rf GD to analysis of non-conducting materials including bulk polymer and silicate paint Direct laser sampling of industrial plastics for discrimination in recycling; the surface coating was removed by pre-ablation and bulk polymer composition was examined via atomic emission spectrum generated A high-voltage sliding spark (20 kV) was applied until dielectric breakdown occurred and a second circuit applied a current pulse of 100-600 A for 5.5 ms at a repetition rate of 20-50 Hz; used in the identification of polypropylene polyethylene and polystyrene and additives Applications of HPLC in size exclusion normal and reversed phase modes to the determination of hetero-atom containing polymers including molecular masses and polar and non-polar compounds; use of metal tags to determine functional groups conducting materials and used for identification of plastics and fillers and other additives method for the determination of As Cd Co Cr and Cu Identification of source of coloured polyethylene bags Use of XRF for detecting catalyst elements and Sliding spark source applied to the analysis of non- Modified EPA microwave nitric acid digestion Various Polyethylene Various Pol yolefins Various Poly (tetrafluoroethylene) MS;GD;S Various Plastics AE;laser;S Plastics AE;spark;S Various AE;ICP;L Various Polymers Various Various Plastics Paint AE;spark;S AE; IC P; L SEMICONDUCTORS- A1 Silicon TXItF;-;S Use of synchrotron radiation source to improve detection limit for TXRF compared to conventional instrumentation; LOD = 8 x lo9 atoms cmP2 elements and simultaneous detection of film thickness and composition on silicon wafers spectrometry with a line width method New design of X-ray optics for improved SIN of light Quantitative detection of major levels of Bi using arc As for A1 Use of synchrotron source microfluorescence system for two dimensional intensity distribution mapping Method for non-destructive measurement of H using charge diffusion and donor-acceptor emission spectra Method of preparation calibration standards for total-reflection XRF Use of 1602+ ion beam for depth profiling to determine the thickness of the native oxide layer Quantitative method for detection of interstitial 0 in wafers using partial least squares multivariate calibration P using a filter reduce wafer temperature by preabsorbing the low-energy component and operation in a helium atmosphere to avoid carbon deposition on sample surface Sample atomization in a planar magnetron discharge and detection using laser excited AFS Samples were dissolved in concentrated hydrochloric and nitric acids (3 + 1) and analysed using matrix- matched standards and a palladium-magnesium chemical modifier; for levels below 5 pg g- Te the digest was evaporated to dryness redissolved in hydrochloric acid and extracted using chloroform containing bismuthiol 11; LOD = 0.3 pg 8-l Synchrotron source depth profiling of ion-implanted 9511808 B Silicon wafer XRF-;S 9511643 Silicon-bismuth AE;arc;S 951233 Bi Fe Ge Silicon wafer Silicon monocrystal semiconductor Semiconductor crystal SIMS and TXRF XRF;-;S 9512586 9511 58 1 AE;-;S H 951857 Ni 0 0 Silicon wafer Silicon wafer Silicon wafer TXRF;-;S SIMS FTI R 9511015 9413205 951197 P Silicon wafer X R F;-$ 9511583 Si Te Pure indium and gallium Indium phosphide 9413039 9 51305 3 AF;magnetron discharge;S AA;ETA;L 388 R Journal of Analytical Atomic Spectrometry December 1995 Vol.I0Table 3 (continued) Technique; atomization; analyte form* Element W W Transition metals Sample treatment/comments Reference Matrix Silicon wafer Tungsten silicide film XRF;-;S X R F;-;S As for B; measurement of thickness of tungsten Analysis of film on silicon wafer using a fundamental 951 1643 9511772 silicide on silicon wafer parameter approach for the soft and ultrasoft X-ray region Samples were etched using a mixture of hydrofluoric and nitric acids; the thickness of the wafer was calculated from the Si concentration of a portion of the etching solution and the rest was dried and the water soluble fraction analysed using ETV- ICP-MS; LOD's were 0.005 ng g- for Cu and Ni and 0.01 ng g-' for Cr and Fe 94/33 13 Sample was etched with hydrofluoric acid vapour Study of proposed new reference material for sputter Use of ETV in conjunction with isotope dilution for depth profiling determination of impurities (Ag Cu Pb Zn) in the range 1 x 108-8.7 x lo9 atoms cm2 with RSD of 2% or better multi-element analysis following vapour decomposition of the surface layer of the wafer analysis of silicon wafer impurities including clean room operation Use of ETV sample introduction for the detection of metallic impurities on silicon wafer surfaces Analysis of wafers and acid cleaning solutions Comparison of post-ash cleaning processes using ammonia hydrogen peroxide water (1 :2 10) mixture; Zn contamination found in hydrogen peroxide Study of vaporization of gallium using ETV into a flame and ETAAS using nitric acid dissolution and direct solid sampling; LOD = 0.06 pg g - ' Direct analysis of semiconductor process gas using a high resolution double focusing MS to remove spectral interferences Oxidative extraction of impurities (Al Ca Cr Cu Fe Na and Ni) from the surface of a silicon wafer using dilute hydrofluoric acid and hydrogen peroxide solution Method for small volume sampling (< 200 pl) in A review with discussion of several methods of Silicon wafers MS;ICP;L 9413079 9413235 Various Various Various (4) Various Various Various Various Various Ca Various Various (7) Semiconductor substrates Gallium arsenide/aluminium arsenide Silicon wafer A A;ETA;L XPSISIMS MS;ICP;L 95/C48 1 Silicon wafer MS or AA;ICP or ETA;L 95/C756 951 1330 Silicon wafer MS;ICP;L 9511387 Silicon wafer VLSI wafers Silicon wafer MS;ICP;L TXRF;-$3 or L TXRF;-;L 9511694 9511 695 Gallium AA;F and ETA$ and L 95/21 27 9512585 Tetraethoxysilane MS;ICP;G AA;ETA;L 951283 1 Silicon wafer GLASSES - Na K Th U REE Various (16) Study of effect on Na content on X-ray intensities observed using a double crystal wavelength dispersive spectrometer Direct determination of K at 0.13 pg g-' level with linearity up to 460 pg g-'; precision reported as 10% or better Comparison of ICP-MS method with detection limit of 1 ng g-' with classical photometry and chelation GC-ECD methods As for Th Synchrotron X-ray microprobe techniques used to measure energy- and wavelength dispersive spectra of REE's in glass Direct sampling using laser ablation with a portion of the aerosol diverted to a mass flow controller to monitor variations in sample transport; accuracy and precision were reported to be of the order of 10% Standards for the analysis were prepared by fusion of known amounts of oxides of the elements of interest in a platinum crucible in a muffle furnace using lithium borate as a flux A transmission type attachment for energy dispersive XRF was developed which was reported to give improved detection limits when used in conjunction with a CAMEBAX microanalyser or SEM; LODs were reported in the range 0.5-5 pg g-' 9511618 Sodium oxide-silica glasses Glass Glass Glass Glass Glass XRF;-;S AE;laser;S MS;ICP- MS;ICP;- X R F;-; S AE;ICP;S 9511890 9511 328 9511328 9511826 9413 182 95/64 9511050 Various (12) Coloured glass XRF;-;S Various NIST SRM 612 Glass XRF;-;S Journal of Analytical Atomic Spectrometry December 1995 VoZ. 10 389 RTable 3 (continued) Technique; atomization; analyte form* Sample treatment/comments Element Matrix Reference 95/1272 Various Braun tube glasses MS;GD;S Various Glass AE;ICP;S Comparison of GDMS with PIXE and ICP-AES; instrument response was calibrated using NIST SRM 612 Glass Direct analysis by sampling using a KrF excimer laser (248 nm output) or a frequency quadrupled Nd:YAG laser (266 nm output) at a repetition rate of 10 Hz; precision 1-3% The dried sample was placed in a platinum crucible treated with water hydrofluoric acid and sulfuric acid evaporated to dryness and the residue dissolved in dilute hydrochloric acid; Ca Fe K Mg and Na were determined using FI-AAS and recoveries reported were in the range 93-110% Round-robin study of slurry sampling involving a variety of sample types including glass; 28 laboratories participated 9511 669 Various (5) Fluorescent screen glass AArF;L 9512514 Various Glass AA;ETA;S 95lC3029 CERAMICS AND REFRACTORIES- A1 Lanthanum and yttrium oxides AA;ETA;L 94/30 13 95/970 The sample was dissolved in HNO and evaporated to near dryness and was extracted using l-phenyl- 3-methyl-4-benzoyl-pyrazolin-5-one in CHCl evaporated to near dryness and diluted with water prior to the addition of several complexing agents and buffered to pH 6.3-6.5; A1 was determined by molecular absorption using a neon source at 622 nm The sample (0.1 g) was decomposed by microwave heating with 0.3 ml of 30% HF and 4 ml of 4 mol 1-' HCl in a PTFE multi-walled vessel; recoveries were in the range 96-99% The sample (10 g) was mixed with calcium carbonate and ashed at 880°C under oxygen; the ash was dissolved in HC1; LOD=4 ng g-' The sample was dissolved in HC1 evaporated to near dryness the residue redissolved in water and mixed 10% potassium citrate and 20% NaOH and diluted with water.The analyte was extracted in 20% cyclohexane 20% tributyl phosphate and 0.02% azoazoxy BN and back extracted into HCl; LOD = 3 pg g-' The sample was decomposed with 1:l HCl Cerium"' was oxidised using KMnO in a perchloric 94/c3 399 acid medium at pH 2.5-3.5 and Ce" was extracted using 1% PMBP in cyclohexane and then back- extracted with 10% HCl Powdered sample (0.5-3 mg) was atomised from a graphite cup furnace and Cu detected by Zeeman effect AAS; LOD = 92 pg The sample (0.4 g) was dissolved in HCl and diluted with water; ammonium chloride was used as a matrix modifier to enhance sensitivity; recoveries in the range 95-107% were reported The sample (50 mg) was ultrasonically dispersed in 25 ml of a hydrochloric-nitric acid mixture and the resulting suspension was digested for 10 min at 50°C; a 100 pl aliquot of this suspension was injected into an FI carrier stream of water which was passed through a 1 ml capacity magnetically stirred mixing chamber prior to analysis Calculation of cement content in concretes based on detecting Fe and assuming proportion as oxide is constant in process carriers used in distillation dc arc technique; Energy dispersive method using Br K-shell X-rays 9513096 9511963 9413330 A comparison of the efficiency of various LOD= 30 pg g-' from a thick potassium bromide pellet secondary target to excite Hf L-lines As for Fe; a 200 pl portion of the sample was injected into a carrier stream of water which passed through a PTFE mixing coil prior to analysis; an analytical range of 0.03-6 pg ml-' was reported A1 Rare earth oxides Molecular absorption Composite ceramic powders AE;ICPL 951923 B High purity graphite MS;ICP;L High purity europium oxide AA;F;L 951927 9413012 B Ca Ce Lanthanum oxide AE1CP;L Silicon carbide and nitride Rare earth oxides A A; ETA; S AA;ETA;L cu Eu Fe Cement AA;F;L Fe Hf Hf Mn Concrete Zirconium oxide Zirconia Cement XRF;-;S AE;arc;S XR F;-$ AA;F;L 9511746 9511208 9511584 9413 3 30 390 R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 3 (continued) Element Matrix Technique; atomization; analyte form* Sample treatment/comments Reference Nd Neodymium yttrium aluminium borate Pb Silicon carbide and nitride Si Boron nitride Si Europium oxide Si Rare earth oxides Th Yttrium AE;ICP;L 9511937 AA;ETA;S AA;ETA;S AE;ICP;L Molecular absorption MS;ICP;L 9513096 9413363 951134 951970 9413310 U Yttrium MS;ICP;L Y Yttria-stabilised zirconia film SIMS Zn High purity europium oxide AA;F;L REE Europium oxide AE;ICP;L REE Lanthanum oxide AE;ICP;L REE Rare earth extract XRF;-;L REE Gadolinium oxide AE;ICPL REEs ( 5 ) High-purity praseodymium AE;ICP;L REEs (5) Rare earth alloys AE;-;L 9413310 9413314 941301 2 9413047 9413101 9413 159 9413 337 95/71 95/77 REEs Scandium oxide REEs Yttrium oxide MS;ICP;L MS;ICPL 9511335 9511391 Nd Lanthanum compounds MS;ICP;L Chemical preconcentration of Nd from matrix by 9413284 separation with Bio-Rad AG 50W X4 resin in the ammonium form and eluted with 0.25 mol 1-' a-hydroxybutyric acid adjusted to pH 4.8 with ammonia; 14'Nd was added for the isotope dilution measurement; LOD = 0.01 ng g-' hydroxide in a graphite crucible at 500 "C; recoveries were reported to be in the range 96-105% with an RSD of 1.4% The crystal sample was decomposed with sodium As for Cu; LOD = 53 pg Sample (20 mg) was mixed with 10 ml of 0.15% magnesium nitrate as modifier and the resulting slurry was sonicated for 30 s; results obtained were in good agreement with XRF The sample (50 mg) was dissolved in 5 ml of 50% HNO filtered and diluted to 25 ml with sub- boiling H,O; the acid soluble Si was determined with recoveries in the range 98-104%; LOD=3 pg g-' The sample was fused with sodium carbonate at 800°C for 10 min then dissolved in HCI and treated with H,SO ammonium molybdate oxalic acid ammonium iron@) sulfate and water prior to detection at 640 nm using a neon source The sample was dissolved in 7 mol 1-' HNO and was subjected to ion-exchange separation by elution with 1 mol 1-' HF and 0.1 mol 1-' HC1 evaporated to dryness redissolved in HC1 and passed through a cation exchange column; Th was separated from REEs by elution with 1 mol 1- ' HF and 0.1 moll-' HCI; LOD=5 pg g-' As for Th; following adsorption on the cation exchange column U was eluted with 2 rnol 1-' Quantitative depth profiling; results were shown to HCl; LOD = 3 pg g-' agree with electron probe microanalysis and ICP-OES data As for Ca; LOD = 3 pg g- ' Computer correction for inter-element interferences; recoveries reported in the range 90- 1 10% REEs were extracted from the matrix using the tributyl phosphate-nitric acid system; optimum instrumental conditions for the analysis were established The sample (0.1 ml) was spotted onto a filter paper dried in an IR oven for 15 min covered with a filter paper and pressed for 10 s under 3000 kg Comparison of direct analysis method (dissolution in dilute HNO,) and ion-exchange separation on Dowex 1 X8 (100-200 mesh) resin which was conditioned with 1 moll-' HNO and methanol ( 1 +9); heavier REEs were eluted with 0.7 mol 1-' HNO and methanol (1 + 9) and lighter REEs were then removed using 0.1 mol 1-' HN03; LOD's of the order of a few mg pg-' evaporated to near dryness redissolved in 7.5 ml ethanol and diluted to 10 ml with 5% HC1; LODs reported in the range 0.73 pg g-' for Y to 17.5 pg g-' for Sm The sample (0.1 g) was dissolved in concentrated nitric acid evaporated to near dryness and redissolved in acid and diluted with water to 100 ml prior to the simultaneous determination of Ce La Nd Pr and Sm Study of interference effects and sensitivity drift; caesium was selected as an internal standard; LOD's were reported in the range 0.005 to 0.027 ng ml-' with recoveries of 94-104% parameters and factors affecting interference effects; mathematical correction for isobaric interferences from oxide and hydroxide ions was employed The sample (0.05 g) was dissolved in 1 1 HCl Discussion of optimization of instrumental Journal of Analytical Atomic Spectrometry December 1995 Vol.10 391 RTable 3 (continued) Element Matrix REEs (14) Europium oxide REE Rare earth oxides Various Graphite Various (9) Silicon carbide Various ( 5 ) Silicon nitride Various ( 5 ) Cement Various Scandium oxide Technique; atomization; analyte form* Sample treatmentfcomments AE;ac arc$ AE;@D;S AE;ICP;S AA;F;L M S:spark;- Various High-purity quartz MS;ICP;L Various Alumina AE;ICP;S Various (21) Alumina and silicon carbide MS;JCP; Various (8) Titanium dioxide Various REE phosphates Various ( 19) Superconductors Selection of analytical lines for 14 elements taking into account matrix interferences and ICP operating parameters Direct analysis using an 8 A discharge for 60 s in an argon oxygen (4:l) atmosphere with a flow rate of 3 1 min- ' through a silica glass cyclonic chamber; LODs in the range 1-100 pg g-' with recoveries of 87-114% Direct analysis using an rf glow discharge pulsed at 50 Hz; detection limits reported to be in the range 3-62 pg g- ' An electrothermal vaporization unit consisting of a tungsten coil furnace was used to introduce an aqueous suspension of silicon carbide powder into the ICP; detection limits were reported in the sub pg g- ' range except for A1 Comparison of slurry sampling and dissolution methods using a Babington nebulizer for the determination of Al Ca Fe Mg and Ti; the addition of freon as an aid to slurry volatilization was also investigated The sample was fused with lithium tetraborate- sodium carbonate ( 1 3) dissolved in hydrochloric acid and analysed for Al Fe and Si content; lanthanum nitrate was added to the solution prior to the determination of Ca and Mg; comparison made with XRF and volumetric methods The scandium matrix was removed as complex sulfate anions by adsorption on a strong alkaline 717 anion exchanger in H2S04-(NH,)2S04 solution; the separation removed over 98% of the scandium present The volatilization of B from hydrofluoric acid was suppressed by the addition of dulcitol; C1 was detected indirectly by AAS by addition of silver Study of effect of colloidal stability of slurry suspensions on sensitivity and precision A sample of alumina was dissolved in an HCl-H,SO acid mixture giving LOD's in the range 0.002-2 pg g-' but an on-line complexation method using hexamethylenedithiocarbamate improved detection; for silicon carbide dissolution using an HN03-H2S04-HF mixture gave detection limits in the range 0.002-10 pg g-' The sample was dissolved in hydrofluoric acid and ion exchange extraction and electrolytic separation techniques were employed to remove the matrix specific to the detection of Cd Cu Fe Ni Pb T1 and U; LODs in the range 0.2 ng g- ' (U) to 90 ng g- ' (Fe) were reported The sample was digested in HNO and HF and evaporated to dryness; the residue was then heated with HNO and concentrated to a volume of 1 ml and diluted to 50ml with water Samples were decomposed with nitric acid and the resulting solution was evaporated with carbon powder; major elements in Y-Ba-Cu-0 Bi-Sr-Ca-Cu-0 and Nd-Ce-Cu-0 superconductors and other trace elements were determined; LOD for trace elements = lop7 to AE;[CP;S or L 10-9 g The separation of Cr Nd Pr and Sm from the matrix was achieved using column chromatography with P507 resin; LODs reported for the REE oxides were in the range 0.23 to 0.74 pg g-' with recoveries of 95-104% Sample (100 mg) was digested using 1.6 ml nitric-hydrofluoric (7:9) at 250°C for 2 h in a sealed PTFE vessel and analysed for Ca Co Cr Cu Fe Mg and Zn Chemical spectrographic analysis of 15 REE oxides after separation with APDC-SH- 1 extraction chromatography; LODs were reported on the range 0.8 to 4 pg g-' with recoveries of 80-1 18% IDMS AE;DCP;L AE;arc;S Various (4) High-purity lanthanum oxide AE;ICP;L Various Boron nitride AA;-;L Various (9) Rare earth oxides Reference 9512247 9512373 9413009 9413023 9413 109 9413 143 9413 190 9413233 9413242 9413275 9413 3 37 9514 95/25 951232 951261 951288 392 R Journal of Analytical Atomic Spectrometry December 1995 Vol.10Table 3 (continued) Element Matrix Various ( 10) High-purity graphite Various Various Various Various Various Various (9) Technique; atomization; analyte form* Sample treatment/comments Reference AA or AE;ETA or ICP; Metal nitride wear coatings AE;GD;S Ceramic powders MS;ICP;L Ceramic powders Sintered electronic ceramics Silicon nitride High-purity quartz Various (25) Cement deposits Various Refractories Various Superconductor films Various Refractories Various (14) Zirconium diboride and disilicide Various (7) Zirconium dioxide Various (9) Alumina Various Superconductor Various Silicon carbide Various Ceramic powders AE;ICP;L AE;ICP;L AA AE or MS;ETA or 1CP;L MS;ICP;L XRF or NAA XRF;-;S XRF;-;S XRF;-;S AE;ICP;L AE;-;S MS;ICP;L AEpc arc$ AE;GD or arc$ AE or MS;ICP;S or L The sample was combusted under oxygen with the addition of sodium bicarbonate and sub-boiling distilled nitric acid and water were used to dissolve the residues; ICP-AES was used to determine B Cd Cu and Si and ETAAS was used to measure Cr Co Mo Ni Ti and V Depth profiling of 2-10 pm metal nitride coatings produced by physical vapor deposition; depth resolutions down to 1 pm reported Study of methods of analysis for alumina silicon carbide and zirconia with particular emphasis on removal of spectral interferences by use of a cooled spraychamber and selective chemical extraction The sample was dissolved in acid in a PTFE vessel and analysed using matrix matched standards; SIMS methods for rapid analysis also described titanate by pressurised acid digestion in a sealed PTFE vessel Comparison of methods for the analysis of silicon nitride including limits of detection for each 951326 Analysis of lead titanate zirconate and barium 95/C682 9 5/C73 6 Study of effect of mannitol dulcitol and sorbitol on the suppression of B volatilization during sample decomposition with hydrofluoric acid; Li and Mg were determined in the same solution as B but Co Cr Cu Mn Ni and Zn were determined separately without the addition of dulcitol Atmospheric deposits of particulate matter within the premises of three cement factories were collected and analysed directly for major components of cement and toxic elements dissolved in mineral acid mixtures evaporated to dryness and heated in a muffle furnace to convert to oxides and ground in an agate mortar prior to analysis Energy dispersive system with a 241Am radionuclide source was used to detect major elements (Ba Cu and Y); good agreement was obtained with results from an ICP-AES hydrochloric acid dissolution method A review of the preparation and evaluation of certified standard reference materials Samples were dissolved in a mixture of HN03-H,S04-HF in a pressurised PTFE vessel and the resulting solutions were analysed using matrix matched standards The sample was loaded directly into the electrode of the source using barium carbonate as buffer for the determination of Al Ca Fe Hf Mg Si and Ti Analytes (Co Cu Cr Fe Ga Mn Ni V Zn) were complexed using hexamethylene dithiocarbamate preconcentrated on a C RP column by reversed phase HPLC and eluted with methanol water mixture Sample mixed 1 1 with carbon powder and placed in a thin walled carbon electrode and analysed for major elements which were Bi Ca Cu 0 and Sr.mixed with ultra-pure silicon carbide or equimolar proportions of silicon and graphite to model the sample matrix; detection limits reported to be in the range 10-760 pg g-' for the dc arc and 0.3-56 pg g-' for the GD Comparison of acid decomposition and slurry sample preparation methods for the analysis of alumina and silicon carbide; zirconium dioxide powders were analysed after removal of the matrix using fusion dissolution and liquid extraction to avoid spectral interferences Samples (borides carbides and nitrides) were Analysis of powder samples using analyte oxides 951924 951997 951999 9511385 9511624 9511627 9 5/ 1702 9511745 9511887 9511960 95/2189 9512387 9512504 9512510 Journal of Analytical Atomic Spectrometry December 1995 Vol.10 393RTable 3 (continued) Element Matrix Technique; atomization; analyte form* Sample treatment/comments Reference Various (14) Aluminium nitride oxide AE;ICP;L A sample (0.5 g) was decomposed with 3 ml of HF 95 12550 silicide (Sialon) plus 1 ml of HNO in a PTFE bomb at 170°C for 16 h then heated with 4 ml of H,PO in a Pt crucible and diluted with water; K was determined by AAS glycerol-2 YO nitric acid-2 YO h ydrofluoric acid solution after ultrasonic agitation (10 mins) and stirring (50 mins) via FI manifold carbon-silica gel microcolumn; Al Cr Cu Fe Pb V and Zn were eluted quantitatively with nitric acid; LODs were in the ng ml-' range Various (8) Cements AA;F;L Sample introduced in the form of a slurry in 30% 9512849 Various (7) High purity europium oxide AE;ICP;L Preconcentration of trace impurities on an active 951C2942 *Hy indicates hydride generation and S L G and S1 signify solid liquid gaseous or slurry sample introduction respectively.Other abbreviations are listed elsewhere. rials are used in applications in direct contact with food it is necessary to assess the potential for extraction of such additives from the polymer matrix. This is normally achieved by the controlled exposure of the polymer to food simulants such as ethanol or oil under protocols specified by regulatory authorit- ies.A method for the detection of organo-tin compounds in food simulants by ETAAS may therefore be of interest (95/430). The sample was injected onto a L'vov platform and Sn was determined directly in corn oil using a matrix modifier (unspeci- fied). The recovery of a 15 ng g-' spike of Sn stabilizer in the oil was 98%. The limit of detection reported was 7 ng g-'. The method was applied to the leaching of methyltin stabilizer from PVC bottles and it was reported that the results of testing at various temperatures demonstrated that Sn was extracted at levels which were safe for consumers. A number of companies use elemental markers as process indicators either for control purposes or for identification of product brands (95/1683).An inter-laboratory trial has been conducted on the analysis of Na in polyacrylate absorbent dust (95/2234). Seven companies which either manufacture cross-linked polyac- rylate adsorbents or products containing the material devel- oped methods of detecting traces of dust in situ based on the use of Na as a marker element. The limits of detection were reported in the range 0.11 to 2.4 pg m-3 with an average of 0.7 pg m-3. A comparison of the accuracy and precision of methods based on AAS and AES was made. The manufacture of carpets is a complex process involving the production of base polymer (e.g. nylon or polypropylene) fibre extrusion and final product assembly.At each stage in this procedure addi- tives may be employed e.g. as catalysts colorants release agents or to enhance fibre surface properties. Consequently the trace element Jingerprint of individual carpet Jibres can be used in tracing the source of the material. This feature has been utilized in forensic applications linking victims or suspects to crime scenes (95/C752). Single fibres were analysed directly using ETAAS and ETV-ICP-MS. It was noted that the multi- element capability of the ICP-MS detection system allowed the practical measurement of up to six elements simultaneously whereas the ETAAS system used had a more restricted linear range and was limited to one channel. The utilization of a direct injection nebulizer in ICP-MS was also evaluated in order to make full use of the elemental range of the technique.However this approach suffered from a lack of sensitivity due to the need for large dilution factors. The alternative approach of laser ablation ICP-MS has been applied to the analysis of plastics and glass from scene of crime situations (95/C787). It was reported that elemental associations in samples as small as 50 pm could be determined. The direct analysis of solid polymeric materials continues to be the subject of attention. A new AE excitation source for solid sampling known as a sliding spark has been applied to the identification of plastics (94/3327 9S/2511 95/C3007). In this technique positionally stable high-temperature sparks are slid over the non-conductive plastic surface. A high-voltage was applied (up to 20 kV) by the spark generator until dielectric breakdown occurred and then a second circuit was used to generate a current pulse in the range 100 to 500 A for approximately 5 ps.Spectra were recorded over the range 185 to 510 nm in a period of just less than 1 s using a linear silicon photodiode detector. It was reported that the system was used to distinguish between PVC and Cl-free polymers (94/3327) and for the positive identification of polypropylene polyethyl- ene and polypropylene (95/2511). The determination of addi- tive and filler components in plastics (e.g. metal carboxylates organotin compounds Pb salts chalk silica titanium dioxide and alumina) at levels in the range 0.02-4%. Ediger (95/C2086) has also made use of the notion of a trace element 'fingerprint' for the identification of polymeric materials using laser-induced plasma emission spectroscopy.Applications described included the examination of car bumpers and dash- boards paints and computer cases. Marcus and co-workers (95/C613 95/C630 95/1849 95/C2104) appear to have devel- oped the rf glow discharge to a stage where it may now be applied to the direct analysis of polymers. The specific example cited was that of the bulk analysis of PTFE. It remains to be seen whether the sensitivity of the approach for the direct analysis of polymers will be competitive with techniques such as XRF which are well established in the industry (95/73 95/1683 95/1778). One of the problems associated with direct analysis of solids is the lack of certijied polymer reference standards for trace element analysis.Four polyethylene materials with Cd contents in the range 40 to 400mgkg-' have been certified by the Institute for Reference Materials and Measurements (IRMM) (95/2707 see also J. Anal. At. Spectrom. 1994 9 349R). Homogeneity testing was carried out using solid sampling in Zeeman-effect ETAAS and the Cd content was certified using IDMS. The development of an HPLC-ICP AES system for the speciation and quantijcation of polymers and lower molecular weight fractions has been reported (95/2646 95/C2949). The system was applied to the separation of non-polar high molecu- lar mass poly(dimethylsi1oxane) by SEC using tetrahydrofuran or xylene as the mobile phase and the separation of low molecular mass silanols by reversed phase HPLC with water- acetonitrile as the mobile phase.Components of the separations 394 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10were detected as Si by ICP-AES (95/2646). More recent work has been applied to molecular mass determination the measurement of polymers containing hetero atoms studies of the degradation of polymers and the use of metal tags to determine functional groups in polymers (95/C2949). This is a fascinating development of the atomic spectrometric approach to speciation and the publication of this work is awaited with great interest by scientists in the polymer industry. 3.2. Semiconductors 3.2.1. Silicon-based materials There can be little doubt that total-rejection X-ray juorescence spectrometry has made a major impact in the field of silicon wafer analysis.A review covering the principles and appli- cations of the technique may be of particular interest (95/1766).The ability of TXRF to provide a rapid means of non-destructive multi-element analysis of semiconductors is now well established (95/1694 95/1695). However now that the viability of TXRF has been established in practical situ- ations such as the analysis of clean room dusts (95/1700) efforts are being concentrated on ways of improving the analytical performance of the technique. The early papers on TXRF stressed the ease of calibrating instrumental response using for example internal standard ratio methods. For ideal thin film samples this approach does indeed generate accurate results. The situation is somewhat more complex in the examin- ation of contamination of silicon wafers where the substrate acts as the reflecting surface for the incident X-ray beam and sample non-uniformity is a factor (95/1015).A set of TXRF calibration standards were prepared by quantitatively depositing Ni on cleaned silicon wafer surfaces. It was found to be important to ensure that the standards consisted of homogenous sub-monolayers sufficiently dilute such that the refractive index of the substrate was not affected in order to achieve good calibration linearity and to minimize matrix effects. The standards thus prepared were certified using Rutherford backscattering. It was reported that using this approach metallic impurities such as Cu Cr Fe Ni and Zn were detected by TXRF at levels of the order of 2 x 10'' atoms cm-2 in about 16 min.The angular dependence of the X-ray juorescence intensity was investigated in another study of contamination of wafer surfaces by TXRF (95/1628). It was found that film type and particle type contamination of a wafer surface layer exhibit different angular dependence. A model was used to calculate the angular dependence of the fluorescence intensity for metals diffused into a silicon dioxide and a substrate. Good agreement was obtained between the calculated and experimentally derived values. It was suggested that this approach could be adopted to help trace contami- nation origins in semiconductor fabrication processes. One of the more disconcerting reports to appear in the year under review concerns the detection of spurious peaks in the trace analysis of silicon wafers by TXRF (95/1394 95/1699).Fluorescence from Fe and Ni K a lines was reported even though these elements were not present on the wafer surface. It was found that these spurious signals emanated from con- taminants in the beryllium window of the X-ray solid state detector and that their intensity was proportional to the tungsten L a radiation measured. An analysis of the window material by ICP-MS revealed the presence of 150 pg g-' Fe and 100 pg g-' Ni confirming the source of the errors. Total reflection XRF can also be carried out using synchro- tron radiation as the primary excitation source. Application of this variant of the technique reported in the last year included the determination of A1 on silicon (95/1808) and depth profiling of Ge in silicon monocrystal (95/1581).While advantage can be taken of the dependence of the fluorescence signal on source intensity the energy of the incident synchrotron radiation beam can cause heat damage to the sample. An experimental arrangement to overcome this problem was described in a study of ion-implanted depth profiles using angle-resolved self- ratio XRF (95/1583). Synchrotron beam damage was avoided by pre-absorbing the low energy component in a foil filter and by placing the sample in a helium environment at atmospheric pressure. The latter also prevented the deposition of adven- titious carbon on the specimen surface. The design of new instruments for the analysis of semi- conductors has been a recent activity amongst instrument manufacturers.An instrument combining X-ray juorescence and difraction capabilities has been described (95/1580). It was reported that the system was based on a glancing incidence X-ray beam which could be used to optimize the penetration depth. The possibility of depth profiling by making use of the occurrence of standing waves was also explored. A high- sensitivity analyser for TXRF has been developed (95/1698). In order to improve sensitivity a multi-layer monochromator was used instead of a germanium detector. Limits of detection for transition metals were reported to be less than lo9 atoms cm-2. The simultaneous determination of film thickness and composition on silicon wafers has been achieved using a new X-ray analyser (95/1643).The optical system was designed to improve SNR allowing the determination of film thicknesses greater than 250 nm. A relative precision of 1% was reported for the measurement of 10% m/m B as oxide in short- and long-term stability tests. The application of the system to the characterization of a tungsten silicide film on silicon was also reported (95/1643 95/1772). A few abstracts were received concerning the application of ICP-MS to the analysis of silicon wafers in the period under review. Methods based on acid or vapour phase decomposition of wafers followed by the determination of trace elements in solution are now well established and a review of the appli- cations of ICP-MS for this type of application in the semicon- ductor industry may be of some interest (95/1330).However there have been several reports of the use of electrothermal vaporization of samples to improve ICP-MS sensitivity in the analysis of semiconductor materials and process chemicals (94/3313,95/532,95/C756,95/1387). The use of acid microetch- ing has been used in conjunction with ETV-ICP-MS to develop a method for depth profiling of silicon wafers (94/3313). Samples were etched using a mixture of nitric and hydrofluoric acids and the thickness of the wafers were calculated from the Si concentration in a portion of the exposed etching solution. The impurities in the etching solution were determined by ETV-ICP-MS. The detection limits achieved ranged from 0.005 ng g-' for Cu and Ni to 0.01 ng g-' for Fe and Cr. A reference material was analysed using this procedure and the results obtained were in good agreement with those found by SIMS.Secondary-ion mass spectrometry remains a valuable tool for examining the distribution of metallic impurities in silicon wafers (95/2586). A study of cleaning treatments for silicon wafers was carried out using SIMS and TXRF as diagnostic probes. It was found that the use of surfactants significantly improved the surface quality of silicon and minimized the concentrations of A1 and Fe found on the surface. The SIMS technique was used in a surface imaging mode to reveal the lateral dispersion of these metallic elements. The study of the behaviour of 0 in silicon materials using SIMS continues to receive attention. These investigations included depth projiling of oxygen vacancy defects in buried silicon dioxide (94/3217) the determination of the thickness of a native oxide layer (94/3205) and oxygen and water reactions on silicon and germanium surfaces (94/3201).The development of a glow discharge atomic emission instru- ment for the imaging of wafer surfaces has been described in two recent conference presentations (95/C633 95/C2068). The Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 395RGD source was designed to sustain multiple discharges simul- taneously. The AE signals from the individual discharges were multiplexed and quantified using Hadamard transform spatial imaging. The system was used for coarse elemental composition mapping on a scale of a few hundred square centimetres with a lateral resolution of 1 mm.The resolution of the device was reported to be limited by the size of the sampling orifices used. Patents concerning techniques for the measurement of elements in semiconductor crystals have been published. These include the determination of H by charge state donor-acceptor emis- sion spectroscopy (95/857) and the detection of metallic elements by injection of a complexing agent followed by photoluminescence (95/1617). 3.2.2. Gallium- based materials A study of the volatilization mechanisms involved in the determination of Ca in gallium by ETAAS has been published (95/2127). Electrothermal volatilization FAAS was used for element specific detection in the vapour evolved during the heating of a graphite furnace. Both elements were introduced to the furnace as major and minor components in nitric acid hydrochloric acid and ammonium chloride media.It was reported that interferences on Ca from gallium present in nitric acid at concentrations up to 3 g 1-1 could be suppressed using a suitable pyrolysis heating stage. A limit of detection for Ca in gallium of 0.06 pg 8-l was reported. A method for the determination of Si in high-purity gallium based on AFS was published (95/1OO7). The sample was directly atomized in a planar magnetron discharge. Detection limits achieved using this approach were claimed to be lower than those achievable using alternative methods. Glow discharge mass spectrometry has been applied to the direct analysis of gallium arsenide (95/C2069). An rf source operated at 13.56 MHz was used for sputtering the sample prior to analysis using a double-focusing mass spectrometer.It was reported that the use of a radial gas input system and optimization of the discharge parameters permitted uniform sputtering and allowed depth profiling of the material. Laser ablation resonance ionization mass spec- trometry is a technique which offers high sensitivity for trace element detection in semiconductor materials. However a very pragmatic report concerning the limitations of laser ablation RIMS in application to the analysis of indium gallium arsenide is recommended reading (95/2203). The sample was vaporized using a Q-switched Nd:YAG in the second harmonic fitted with a photodiode detector which was used to trigger the measurement system. Two pulsed tunable dye lasers pumped by a common excimer laser were used to simultaneously and selectively photoionize Ga and In.The ions were collected and accelerated to 2.9 keV towards a time-of-flight MS system. It was found that the action of the laser-induced changes in the chemical composition of the sample as identified using SIMS. Furthermore there was a lack of selectivity in the laser ablation event which inherently constrained the production of neutrals and ions. It was concluded that the atomization step was the least characterized of the whole process and the most difficult to control. Finally reports concerning sputter depth projling of gallium arsenide multi-layer structures using SIMS may also be of interest (94/3211 94/3235). 3.2.3. Indium phosphide-based materials Few reports were received concerning the analysis of indium phosphide or other semiconductor materials during the period under review.Indium phosphide single crystals are used as substrates in a range of applications including light-emitting diodes laser diodes solar cells photodetectors and optoelec- tronic integrated circuits. The performance of these semicon- ductor devices can be significantly influenced by defects in the indium phosphide material and doping of crystals with elements such as Te can result in the production of wafers that are almost dislocation-free. Consequently a method has been developed for the determination of Te in indium phosphide by ETAAS (95/3053). The sample was dissolved in a mixture of concentrated hydrochloric-nitric acid (3 1).For samples con- taining more than 5 pg g-' Te the diluted solution was injected into the furnace with the addition of a palladium-magnesium chemical modifier and the response was calibrated using matrix-matched standards. Where the Te content of the samples was less than 5 pg g-' the digest was evaporated to dryness the residue dissolved in hydrochloric acid and the Te was extracted into chloroform containing bismuthiol 11. The organic solution thus obtained was directly injected into the furnace. A detection limit for the latter method of 0.3 pg g-' was reported for a 500 mg sample. A new approach employing photoluminescence spectroscopy has been described for the identification of impurities in indium phosphide (95/2324). The method was based on selective low-temperature resonant exci- tation in donor-acceptor pair spectroscopy for acceptor identi- fication.While this method was reported to have been successfully applied to gallium arsenide the lack of impurity binding energy data for indium phosphide had prevented the use of the technique with this matrix. High-purity indium phosphide was ion implanted with known levels of impurities in order to make progress in the development of a database of acceptor binding energies. The identification of donor species using high magnetic field low temperature resonant photo- luminescence spectroscopy was also reported. A method for the determination of Si in high-purity indium using laser atomic fluorescence may also be of interest (94/3039). 3.3. Glasses Ceramics and Refractories 3.1 .l.Glasses Most of the work on the characterization of glasses reported during the period under review has concerned methods of direct analysis of the solid material. The application of laser ablation to solid sampling prior to the direct analysis of glasses continues to attract attention (see also ,I. Anal. At. Spectrom. 1994 9 351R and 1993 8 337R). However the most recent work reported has utilized UV lasers for ablation and AES rather than ICP-MS for detection. Thus an excimer laser has been employed for the detection of trace K in glass by AES (95/1890). The laser was used in this application as both the atomization and excitation source and the AE sig- nal was acquired by direct optical observation of the laser plume. The response from the instrument was linear up to 460 pg g-' K with precision typically of the order of 10% relative.A detection limit of 0.13 pg g-' K was reported using this system. The use of UV lasers for solid sampling in ICP-AES has been the subject of a recent investigation. A picosecond frequency-quadrupled Nd:YAG laser (output wavelength 266 nm) and a nanosecond krypton fluoride excimer laser (output wavelength 248 nm) were used to study preferential volatilization of analytes from glass samples. The influence of laser beam properties such as pulse width power density and spot size were investigated by monitoring the ICP- AES signal with respect to time. Silicon as the major compo- nent of the matrix was used as an internal standard. Excellent precision of the order of 1 to 3% relative was obtained using this approach.Quantitative data were published for the analy- sis of prototypical glasses using this system. A method for the analysis of glass powders by laser ablation ICP-AES has also been published (94/3 182). Samples were vaporized using a frequency-doubled Q-switched Nd YAG laser (pulse energy 7.5 mJ repetition rate 5 Hz). A 5% portion of the laser-ablated sample aerosol was diverted to a piezo-electric micro-balance mass secsor in order to monitor and hence normalize variations in the amount of sample ablated and transported to the ICP 396 R Journal of Analytical Atomic Spectrometry December 1995 Vol. 10torch. During the solid sampling process standard solution was nebulized and added to the laser ablated aerosol to generate a standard additions curve for the analyte.It was reported that this procedure could be used to correct for plasma-related interference effects. Precision and accuracy were established to be of the order of 10% relative for the determi- nation of 16 elements in four glass samples. Given the recent development of ICP optical instruments utilizing an axial configuration to improve sensitivity and array detectors to provide a simultaneous multi-element capability it is confi- dently predicted that laser ablation solid sampling for AES will feature significantly in this field in the future. The new generation of glow discharge sources appears to offer a means of direct solid sampling for the MS and AES analysis of insulating materials such as glass (94/3270).Recent conference reports have focused on the use of rf GD sources for MS but although glasses are mentioned few practical details are given in the abstracts (95/C612 95/C631). The use of such a device in the AES mode has been reported for the analysis of multi-component glasses (95/C3005). The rf GD source was coupled to a rapid sequential scanning IMAGE monochromator and this allowed the full wavelength spectrum to be acquired in less than two minutes. A linear dynamic range of 10" was reported for the system and performance was illustrated with a multi-element scan of a NIST glass standard (SRM 1412). The instrument was claimed to provide detection limits at low pg g-' levels which were equivalent to or better than the performance of XRF in such applications without similar susceptibility to matrix interferences.The analysis of insulators can also be achieved with dc glow discharges if a secondary cathode is employed (95/C503). This approach was adopted for the GDMS analysis of glass. A tantalum diaphragm with a 4mm sampling hole was used to achieve stable signal. The use of materials with higher sputter yields resulted in deposition on the surface of the sample and this effectively prevented the generation of signals. It was noted that the blank signals obtained with the system were signifi- cantly higher for glasses than for other sample types. A publication comparing the use of GDMS with ICP-AES and PIXE for the analysis of television tube glasses may also be of some interest (95/1272). X-ray juorescence techniques are widely used in industry for the analysis of glasses as raw materials and in component manufacture. Variations in the observed XRF intensity of Si Ka lines in a soda glass matrix have been studied as a function of sodium concentration (95/1618).Significant changes in peak energy line width and intensity were found using a double- crystal wavelength-dispersive spectrometer for the detection of Si. Theoretical spectra of Si were constructed from calculation to explain the changes in X-ray intensity. X-ray microjuoresc- ence has been utilized for the examination of individual syn- thetic glass particles (95/1715). A Monte Carlo model was developed to simulate X-ray fluorescence and Compton scat- tering from spherical and irregularly shaped particles. the model was compared with experimentally observed data.The characterization of small glass particles (NIST SRM 470 glass spheres) has also been achieved using energy dispersive XRF as a detector for electron microscopy (95/1050). A transmission type attachment was developed in which the X-ray detector viewed the specimen through a hole in the objective lens. Improvements in limits of detection were claimed for this configuration. The system was applied to the analysis of NIST SRM 612 glass and LODs in the range 0.5 to 5 pg g-' were reported. A review comparing the application of EDXRF with AAS and ICP-AES for the analysis of small glass fragments may also be of some interest (95/339). 3.3.2. Ceramics and refractories The characterization of ceramic and refractory materials con- tinues to be an important area of research in analytical atomic spectrometry.The number of abstracts received concerning ceramics has grown significantly over the last few years as technical developments in instrumentation have led to new applications. The resistance of oxide nitride and carbide ceramic materials to chemical attack is one of the features that makes them attractive for industrial usage. However this means that analytical chemists face difficulties in decomposing these materials prior to solution analysis using for example ICP-AES or AAS. Although such methods are now well established in the literature new procedures continue to be published for this type of application and a summary of these is provided in Table 3. Introduction of the sample to the atomizer in the form of a slurry obviates the need for time- consuming acid decomposition methods although the high temperature stability of some ceramics can be problematic.Thus applications of the slurry procedure have been described for the ICP-AES analysis of alumina (94/3242) silicon carbide (95/25 10) and silicon nitride using halocarbon assisted vaporiz- ation (94/3109). ETAAS may also be utilized in this context for example for the determination of Si in boron nitride using magnesium nitrate as a matrix modifier (94/3363). The use of electrothermal vaporization of slurries for sample introduction in ICP-AES has also been described (94/3023). In this case a tungsten coil furnace was used to achieve high heating rates in the vaporization of silicon carbide.The simultaneous detec- tion of Al Ca Cr Cu Fe Mg Mn Ni and Ti in aqueous suspensions of silicon carbide powder was achieved with detection limits obtained in the low- to sub-pg g-' range. Where the electrothermal vaporizer substrate is graphite care must be taken to ensure the volatilization of carbide forming elements (95/C2093). In this work a complex modifier con- sisting of a 1 1 mixture of barium oxide and cobalt fluoride was reported to decompose ceramics such as silicon carbide and silicon nitride thus allowing the vaporization of impurities. An ETAAS method for the direct analysis of silicon carbide and nitride ceramics may be of interest in this context (95/3096). The sample was ground to a particle size of less than 20 pm and mixed with 2.5 times the amount of graphite powder.A proportion (0.5 to 3 mg) of the mixed sample was atomized directly from a graphite cup type furnace. It was reported that double peaks were observed in the AA measure- ment of Cu. It was concluded on the basis of XRD evidence that the first peak arose from the vaporization of Cu from silicon while the second peak was attributed to the release of Cu from silicon carbide. Detection limits for Cu and Pb were 92 and 53 pg respectively. The analysis of silicon carbide powders using dc GD AES after mixing with copper and by dc arc AES after mixing with graphite and a cobalt fluoride- barium nitrate modifier may also be of interest (95/2504). GD AES has also been utilized in depth profiling in nitride coating processes (95/C682 95/2325).Inductively coupled plasma mass spectrometry continues to be applied to the analysis ofceramics primarily because of the sensitivity of the technique. However ICP-MS is subject to spectral interference effects below mass 80 and it is this region of the spectrum which is particularly important in the analysis of ceramic materials. Broekaert and co-workers (94/3275 95/C736 95/2189) have developed methods for the avoidance of spectral interferences in such applications. For alumina a dissolution procedure based on treatment with hydrochloric and nitric acids in high-pressure PTFE vessels was developed which allowed the introduction of up to 400pg g-' of the matrix element to the ICP-MS. It was reported that spectral interferences from Cl could be significantly reduced by cooling the ICP-MS spraychamber.Detection limits in the range 0.002 to 2 pg g-' were achieved using this approach (94/3275). An on-line preconcentration method for the separation of Co Cu Cr Fe Ga Mn Ni V and Zn was described in which the alumina was subjected to acid decomposition and the analytes Journal of Analytical Atomic Spectrometry December 1995 Vol. 10 397 Rwere complexed in solution using hexamethylene dithiocarba- mate and separated on a C18 column by reversed-phase HPLC using a methanol-water eluent (94/3275 95/2189). In the analysis of silicon carbide a multiple (nitric sulfuric hydroflu- oric) acid sample treatment was reported to give rise to spectral interference effects which effectively limited the detection limits for some elements such as Mg to 10 pg g-l(94/3275).However a later conference abstract indicated that decomposition of silicon carbide with concentrated sulfuric acid is also effective and evaporation of the solution to near dryness reduces spectral interferences arising from the presence of sulfur species (95/C736). The application of laser ablation ICP-MS to the direct analysis of titanium dioxide powder has been described (95/2616). The powder samples were pressed without a binder into a pellet and an internal standard was used to normalize the response to achieve satisfactory accuracy for the determi- nation of trace elements. It was claimed that the method was suitable for use in a quality control environment. The determi- nation of impurity elements (Fe Cu Cr Ni Cd Pb T1 and U) in titanium dioxide has also been carried out after acid dissolution using IDMS with a thermal ionization source (94/3337).Detection limits in the range 0.2 pg 8-l (U) to 90 pg g-' (Fe) were reported. An XRF spectrometer equipped with multi-layer pseudo crystals has been used for the quantitative determination of C 0 and N in ceramic powders (95/1716). Although the sensi- tivity of the technique was reported to be low accurate results were obtained in the analysis of aluminium and silicon nitrides by optimization of the sample preparation and counting strat- egy and by regular recalibration of the instrument response. The application of a fundamental parameter program to the analysis of light element compounds has also been described (95/1718).The program was reported to account for both primary and secondary radiation scattering effects. The exam- ination of oxides and nitride responses were compared with the stoichiometric values for known compounds. While compu- tational techniques can be used to good effect in semi- quantitative analysis the most accurate quantification will still be achieved using calibration standards. Publications concern- ing the preparation of standard materials for XRF will therefore be of interest to those engaged in the analysis of ceramics and refractories (95/1745 95/1806). Fewer abstracts were received in the year under review concerning the characterization ofhigh-temperature oxide super- conductors perhaps indicating that the initial search for satis- factory analytical methods is now over. A comparison of XRF and ICP-AES for the determination of Ba Cu and Y in superconducting thin films has been published (95/1702).Although the two methods agreed to within 5% after correction for self-absorption effects in XRF the precision for the ICP procedure was of the order of 0.1 to 0.2% relative when an internal standard was employed. The stoichiometry of high- temperature superconducting films has also been studied using synchrotron radiation excited XRF (95/1741). Detection limits of the order of 5 x 1013 atoms cmP2 were reported and the technique was also applied to the measurement of film thick- ness. Other abstracts which may be of interest in this area included methods for the determination of major components and impurities in superconducting materials using laser ablation AES (95/37) and arc AES (95/25 95/2365 95/2387).The development of methods for the analysis of rare earth oxides continues unabated although the volume of abstracts received does not in itself indicate dramatic progress. The examination of spectral interferences encountered in the analy- sis of REE materials by ICP-AES and ICP-MS is hardly novel yet papers continue to be published concerning these effects (see also J. Anal. At. Spectrom. 1994 9 353R). A summary of the methods employed in such applications is provided in Table 3. A review of well established sample dissolution and separation and concentration techniques for the analysis of rare earths by ICP-AES and ICP-MS provide more rewarding reading (95/1852). Even so the majority of the work reported in the period was devoted to the development of separation and preconcentration methods to remove matrix effects.Thus methods have been reported involving resin-based ion extrac- tion and separation for the analysis of rare earth oxides using 95/257). In a slightly more novel approach an FI-ICP-AES system has been described for the determination of trace non- rare earth elements in high purity europium oxide (95/C2942). The sample was passed through a carbon silica gel preconcen- tration column on line in the FI system. In the pH range 3 to 6 Al Cr Cu Fe Pb V and Zn were retained on the column and eluted quantitatively using nitric acid. Recoveries were reported in the range 85-97% for the analyte elements of interest resulting in enrichment factors in the range 8- to 12-fold.A method for the determination of ultra-trace level Nd in high purity lanthanum compounds by ICP-MS is worthy of attention (94/3284). Isotope dilution was used to improve accuracy and avoid the need for complete recovery of Nd. The sample was dissolved in acid a spike of Nd 145 was added and the solution was applied to a column containing AG 50W X4 resin in the ammonium form. Rare earths were eluted using 0.25 mol 1-' a-hydroxybutyric acid and adjusted to pH4.8 with ammonia. Although the eluate could be transferred to the ICP-MS on-line better precision was achieved using fraction collection and using further concentration if required. The concentration of La'" was reduced by a factor in the range lo4 to lo5 using the method.A detection limit of 0.01 ng 8-l Nd was reported. Finally only a few abstracts were received concerning the direct analysis of solid rare earth materials during the period under review. These included the depth profiling of yttria- stabilized zirconia film by SIMS (94/33 14) improved detection of REEs using WD XRF (95/2500) and the study of chemical equilibria in rare earth oxides using GDMS (95/1278). ICP-AES (94/3101 94/3310 94/3337 94/C3399 95/232 LOCATION OF REFERENCES The full list of references cited in this Update have been published as follows 9412995-9413279 J. Anal. At. Spectrom. 1994 9( 1 l) 307R-318R. 94/3280-94/C:3502 J. Anal. At. Spectrom. 1994 9( 12) 357R-364R. 9511-95/182 J. Anal. At. Spectrom. 1995 10( l) 1R-60R. 951183-951469 J.Anal. At. Spectrom. 1995 10(2) 49R-59R. 95/470-95/<:849 J. Anal. At. Spectrom. 1995 10(4) 113R-125R. 951850-95/1159 J. Anal. At. Spectrom. 1995 10(5) 127R-138R. 9511160-9511597 J. Anal. At. Spectrom. 1995 10(6) 155R-171R. 95/1598-95/<:2275 J. Anal. At. Spectrom. 1995 10(7) 173R-198R. 9512276-9512891 J. Anal. At. Spectrom. 1995 10( 8) 229R-251R. 95/2892-95/3361 J. Anal. At. 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