ISSN:0306-1353    

DOI:10.1039/AA97505FX001

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

PART I FUNDAMENTALS AND INSTRUMENTATIONPart I : Fundamentals and Instrumentation 3 1 Light Sources 1.1 HOLLOW CATHODE LAMPS Much of the new work reported involving the use of HCLs has been concerned with the modification of lamp design or operational parameters for specific analytical purposes. Potential applications of new types of demountable spectral lamps, based upon the Sullivan- Walsh high-intensity HCL, have been reported, both as high-intensity sources for AFS (844) and as AES excitation sources (891) (See also section 2.3). If the booster filaments h the lamps incorporate lanthanum hexaboride (844) they may be rapidly regenerated, even after repeated exposure to air.Stephens and Flinn (772) have described a multi-cathode discharge source which contained separate, sequentially-operated cathodes fabricated from wires of appropriate metals.The useful life was SlOOh, but the emission intensity was 1-2 orders of magnitude lower than that from corresponding single-element lamps. Demountable ‘see-through’ HCLs have been described by Bath and Woodriff (1 129), for use in conjunction with a sequentially-pulsed HCL continuum source for simultaneous automatic correction for non-atomic absorbance signals.The principal advantage of such a system is the low light loss. Sealed ‘see-through’ lamps have been described earlier by Strasheim and Butler. (Appl. Spectrosc. 1962, 16, 109). A claim has been made (1359) that the fabrication of cathodes by compression moulding from metal particles of less than 70 pm in diameter at normal temperatures leads to 2-+fold increases in absorption- line intensities.Interest in the routine use of pulsed operation of HCLs has not been widespread. They have been used, however, in molecular absorption and fluorescence spec- trometry (710) and also as excitation sources for AFS. A mini-computer-controlled power supply (726) for the latter use has been manufactured and evaluated.Peak and average currents, d.c. level, and pulse width and period could be individually controlled with this system (see also ARAAS 1974, 4, 3). It is difficult to envisage how the advantages of using HCLs operated in this mode could be regarded as sufficient to justify their widespread use in AFS at the present time, except when multi-element systems are to be developed.Piepmeier and de Galan (640, 644, 1126) have studied the variation in the properties of Cu and Ca lines emitted by HCLs operated in a pulsed mode. Pulses up to one ampere and widths as short as lops were employed at repetition frequencies between 3 and 300Hz. Temporal changes in the line profile of a pulsed lamp give rise to the observation of an apparent line profile whose shape depends upon the detcctor-system response character- istics, and thus influence the analytical curves.For the Ca 422.7 nm line (640), self-reversal and line width increased with radial distance from the centre of the cathode bore and the time during the pulse, and decreased with increasing modulation frequency up to 6.4 kHz. Up to 1-6 kHz, electronic modulation gave narrower and more intense lines than optically-chopped d.c.operation. Torok and Zaray (1456) have described the construction of purpose-built twin HCLs which may be cooled with liquid air and could be used for studying excitation processes in hollow cathode discharges and in emission analysis. Wagenaar and de Galan (594) studied the influcnce of spectral line profiles upon analytical curves in AAS.A Fabry- Perot interferometer was used to study Ag and Cu line profiles before and after flame absorption at various HCL currents. The measured profiles were digitized and deconvoluted and the flame-shift values were applied to the calculation of analytical curves. Good agreemcnt was obtained between the directly measured curves 2nd the curves thus calcul- ated.Hannaford (798) has also reviewed the theoretical aspects of the influence of spectral line profiles in AAS. Human (845) has measured the shapes of the Ca 422.7 nm and the Cr 425.4 nm lines from boosted-output HCLs with a pressure-scanning Fabry-Perot interferometer, A two-4 Analytical Atomic Spectroscopy layer model was assumed for the source and theoretical line profiles were calculated, assuming a Gaussian shape for the absorption line in the lamp.The theoretical profiles were fitted to the measured profiles and from this the Doppler halfwidths and optical densities in the two layers were obtained and temperature values calculated. Zechev and co-workers (1 528) found considerable Gaussian and Lorentzian broadening of the Fe 372.0 nm line. Predictably, it was found that increasing the discharge current stimulated the Gaussian component of the spectral profile, and a correlation was found between the Gaussian component and the cathode voltage drop.An echelle spectrometer (1 370) has been used to measure spectral line profiles for Ca, Ag and Al. Increases in line-width resulted in a corresponding poorer AA sensitivity. The excessive Doppler broadening of B HCL lines in Kr-filled HCLs is avoided in Ne-filled sources; the latter (858) have therefore been used for B isotopic analysis using the 208.8/208.9 nm doublet.A further example of line overlap in AAS (137) has been reported-Re has been determined at 346.046 nm, using the neon line at 346.053 nm as a source. A detection limit of 11 pg/ml was obtained in a N20/C,H2 flame.It is perhaps worth noting here that the performance of HCLs for a number of elements, notably As, B, Se, U and the rare earths, continues to be, at best, mediocre and nogreat progress has been made in this area. Other references of interest - Fe - Ne HCL spectrum: 302 1.2 ELECTRODELESS DISCHARGE LAMPS Interest in the use of EDLs has continued, prompted perhaps by reports of the substantial improvement in stability of the emission from EDLs attained by external temperature control (ARAAS 1974, 4, 57).Fixed temperature (1192) enables satisfactory results to be obtained from simultaneous excitation of elements with markedly different optimum tern- perature requirements, and the merits of EDLs as multi-element excitation sources (1 192, 1122) have again been stressed.The mdin applications at present of EDLs are: (a) as intense excitation sources for Zn and Cd, where AF detection limits are vastly superior to those obtained by AA; and ( b ) as sources for As and Se in AA analysis, where the stabilityand intensity of the corresponding HCLs is so poor. From a fairly rigorous study of the optimization of the cxperimental parameters in- volved in microwave-excited EDL construction (725), it was concluded that lamp shape is the most important factor.However, although the familiar 40 mm x 8 mm i.d. dimensions were found to give the most efficient coupling, an additional ‘ballast’ section 60 mm x 5 mm i.d. improved the lamp operating characteristics. Volatile covalent hydrides (1 132) have been used to prepare EDLs for selected group IV, V and VI elements, The primary advantage of this procedure is that it allows the introduction of a reproducible amount of element into the lamp blank.Lamps prepared in this way were reported to be intense, reproducible in characteristics, stable over a wide temperature range and long-lived. The spectral characteristics of S, Se, As and P EDLs (642) beween ca 177 and 217 mm have also been discussed.A detailed study of the properties of alkaline earth EDLs (1075) as light sources to be used in a strong magnetic field for Zeeman scanning of absorption profiles in flames has been reported. Temperature, line width, fill gas, unwanted line emission, stability and useful life were investigated. 1.3 LASERS Although there has been continued speculation about the potential uses of laser excitation sources in chemistry in general (563) and analytical chemistry in particular (680, 732, 649),Part I: Fundamentals and Instrumentation 5 useful novel applications of these sources in routine analytical atomic spectroscopy are scarce.Dye lasers have again been used (see ARAAS 1974, 4, 281) to monitor very low Na vapour densities (526, 1000) by AFS and studies of intracavity quenching of laser emission (445, 960, 1009) have been extended by several workers.Absorption by Na, Ba, and Eu (445) and Na, Li, Sr, Ba and Cs (1009) has been observed using air/ C,H,flame atomizers; the method has also been applied to K, Rb and La salts (960) using atomization from a graphite electrode.A narrow-band tunable dye laser has also been used (536) to excite Ba atomic fluorescence in a level-crossing study on the 6s 6p lP1, level (553.5 nm) of Ba(1). The effect of dye laser emission bandwidth (52s) on absorption coefficients and reson- ance excitation has been studied on a theoretical basis. Generalised expressions were derived for absorption coefficients that take into account not only the atomic Lorentz and Doppler broadening, but also the line shape of the irradiations.The construction of a continuously-dumped argon-ion laser (238), suitable for phase fluorimetry has been des- cribed briefly. Other references of interest - Iodine laser emission: 150, 1012 1.4 CONTINUUM SOURCES Some further results of preliminary studies (ARAAS 1974, 4, 4) of the use of exploding wires (689, 711, 847) as intense ultraviolet continuum excitation sources have been des- cribed by Sacks et ul.The wires are exploded by capacitive discharge. At 220 nm, the peak irradiance was more than five orders of magnitude greater than that obtained from a 1*6kW Xe arc lamp (689), with a RSD of 0-054 between shots. Optimum intensity was obtained in an Ar atmosphere (711) and the output increased almost linearly with pressure over the range 100 to 700 torr, becoming virtually pressure independent at above 100 torr.A theoretical model (349) has been formulated for calculating the spectral radiant emission from a pulsed inert-gas plasma arc lamp. Continuum sources such as a 200 W Xe- Hg lamp at wavelengths below 300 nm (731) have been shown to be very promising for AAS when an echelle monochromator is employed to attain adequate dispersion.An inter- esting alternative approach has also been suggested, based upon selective modulation of resonance lines (1 1 20), using the droplet-generator system of Malmstadt and Hieftje (Anal. Chem., 1968, 40, 1860) to periodically introduce into a flame droplets of metal-salt standard solution.This pulsating atomic vapour was used to effect selective modulation of resonance lines against an unmodulated, continuum background. 1.5 ZEEMAN - SPLIT SOURCE23 IN AAS A great deal of interest (369, 770, 990, 991, 1176, 1235) has been shown in the analytical potential of the use of Zeeman splitting (described briefly in ARAAS, 1974, 4, 18). The method has been applied, for example, to the determination of Hg in hair and NBS steel samples (369), which had received no previous chemical treatment. Much attention has been paid to the design and operation of purpose-built sources, including both EDLs (770), and d.c. discharge lamps (990) employing wire or sheet-metal electrodes. It has been claimed (991) that Zeeman splitting can be used to compensate for source drift, as well as scatter. It seems probable that interest in this technique has been promoted to a great extent by the stringent requirements for precise background correction which are imposed by a number of electrothermal atomizer systems, However, it should be remembered that the technique is not a universal panacea, because of the variability of the splitting pattern from element to element.

ISSN:0306-1353    

DOI:10.1039/AA9750500001

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

6 Analytical Atomic Spectroscopy 2 Excitation Sources and Atomizing Systems 2.1 ARCS AND SPARKS 2.1.1 Fundamental Studies The temperature of, and the movement of materials in, the various plasmas available to spectrochemical analysis continue to be investigated. Vulcanovic and his co-workers pro- vide valuable information that will help in the understanding of the sources of spectra. ‘Liquid bullets’ have been injected into the plasma of a d.c.arc in air (graphite) and the spatial intensity distribution of Na (213), CaO (666) and their residence time in the arc recorded with a high-speed camera (214). It was suggested by Petrovic et nl. (629) that the distribution of particles in the plasma can be improved by constricting the arc in cooled metal tubes. According to Decker and McFadden (211) one should be careful where one looks for the region of maximum sensitivity since in their opinion this region will, for some elements, be found quite a distance off the axis of the plasma.The position seems to be elemental dependent and related to the inside diameter of the electrode crater. Stupp and Overhoff have used some sophisticated apparatus to study the vaporization of graphite in the d.c.arc (403). A computer programme to enable determinations of the radial dis- tribution of temperature and electron pressure has been written (1 321). Calculations of the optimal characteristics for d.c. arc operation have also been made and reported in detail (284). From such information i.e. the relationship between plasma characteristics, temper- ature and line intensity, improvements have been made by Kubota and Ishida (1296). The work of Walters et al, on the subject of spatial and temporal resolution of sparks is noteworthy (1090, 1091, 1092, 1093, 1094, 1095, 1096).These papers were presented at the I1 F.A.C.S.S. meeting; the abstracts in the programme stimulate more than average interest in the work of this progressive school. 2.1.2 Modifications of Existing Systems Two papers presented at Euroanalysis 11, 1975 confirm that the spectra produced by a d.c.arc can be affected significantly by a magnetic field. In the first paper (1306), it was sug- gested that an alternating magnetic field can influence several spectro-analytical problems. The second paper (1 31 1) was concerned only with improving and explaining the sensitivity of 9 volatile elements.Pavlovic and Mikailidi further suggest that the most marked effects occur when the cathode is the sample-carrying electrode. There are still modifications and studies to be made of existing systems which can improve sensitivity and other analytical parameters, Time resolution of the arc (1486), often called selective distillation, has improved limits of sensitivity and line identification.Strasheim et al (579) have improved their method of analysis for various A1 alloys. The addition of a third electrode to the well tested ‘one-up, one-down’, system is claimed to “increase the stability of arc ignition” (341). A Kenotron (a switch) introduced into a spark source (950) has increased the pulse voltage by a factor of two and makes this source suitable as a “universal atomizer for AAS studies”.Unipolar sparks with highly reproducible current impulses are produced with a new circuit designed by Mast and Pfeilsticker (592). Used in the mode suggested, 1000 impulses are superimposed at a repetition rate of 3 kHz. The liquid layer on solid sample spark technique has been exploited by Ohls (1303).This system when compared with other methods used in an industrial steel laboratory also produced greater sensitivity. The virtues of time resolved spark source have been expounded by Crouch (1 10, 646, 1347). Details are given for the determination of a number of elements.Part I : Fundamentals and Instrumentation 7 2.1.3 Mixed Sources Since the early 1930’s there have been a number of attempts to combine arcs and sparks with flames.Recently Woodruff and Malmstadt (709) have used such a coupled system to analyse a variety of solutions. A report (174) from the Macaulay Institute- the home of “cathode layer arc spectroscopy”- described a triple-fl ow gas sheathed d.c. arc which it claims with typical conservative realism, “is giving better results”.Fijalkowski and CO- workers (626) examined three types of discharge and the ‘best conditions’ for the determin- ation of some difficult non-metallic elements. Vapours produced by arcs and analysed by sparks (767) and those produced by sparks and analysed by flames (841) have been reported. Solutions, after desolvation, have been directed into arcs (371) and sparks (45).In the latter method the analysis of rare earths has been performed with better reproducibility than with the porous-cup technnique. Powder aerosols injected into d.c. arc plasmas gave surprisingly reproducible results with RSDs of -0.05 at levels of a fraction of a ppm (591). 2.1.4 BuEers Investigations into the nature and effect of spectroscopic buffers has continued, albeit at a slightly slower pace than of recent years.Buffering, it is claimed, offers its main advantage by improving the residence time of elements in the plasma (1392). The role of heat of evaporation has been studied by Lakatos (587) in the analysis of petroleum products. The temperature of the anode spot, responsible for the uptake of sample into the excitation areas, has been studied under buffering conditions by Decker and Kobus (576).No anal- ytical applications were attempted. Alkali metals still form the basis of most buffers. With the pressure for increased reproducibility of analytical information, Zadgorska et a1 (1 31 3) found that the various halides and common acid salts of potassium they used should be selected with care. Rippetoe et al.(234) used KCl to improve the stability of a d.c. arc plasma. The use of 1% w/w NaCl buffer for rare-earth analysis has been studied (418); unfortunately no comp- arisons were given with other techniques. Work on NaCl mixed with NaF and Ga,O has also been carried out (418). Lower determination limits for a wide range of elements were claimed. NH,F added to samples was used in an attempt to understand plasma be- haviour (665).Tripkovic (625) has investigated the effects of halogens introduced into plasmas. Iodine was mixed (5:l) with graphite and light output of the source studied. The conclusions were that without iodine, at certain levels, no lines for Te, Sb, As, M o and Ni were observed. When iodine was added in the manner described, the lines of all the elements were seen.No analytical applications were attempted. Organic reagents containing iodine were used to suppress the interference of Mo in the determination of a wide variety of elements in molybdenum oxide (39). The addition of Ar to the air around the plasma and Ba to the sample was foundto improve both the sensitivity and detection limits of numerous elements (38, 1498).At a recent conference in Poland several workers reported that mixtures of air- Ar-N, could be manipulated to improve the analysis of aluminium alloys (627). 2.2 PLASMAS 2.2.1 d.c. Arc Plasmas Within the past year there has been an explosion of interest in spectrochemical analysis using plasmas and a review of available d.c. arc plasmas has been made (1403). This ex- pansion is logical and is an extension of the interest by analysts in AAS into multi-element determination.The temperatures (< 300K) of the commonly used flames are insufficient i8 Analytical Atomic Spectroscopy to provide the required analytical sensitivity for many of the elements often sought. It is not surprising that electron temperatures and concentrations have been studied by several workers (206, 597).The need for multi-element determinations has led many workers to develop ‘new’ devices by adapting existing units. Vickers (648) has rotated a d.c. arc on a disc electrode, thereby generating a plasma with a “hole in the middle” into which the solution may be injected. Levels of background, interference effects and detection limits have all been studied, Denton (698) attempted to use an ‘old’ arc plasma source but found that too much improvement was necessary to enable him to perform the required analysis.Layman and Hieftje (226) used a computer to perform the manipulations of their plasma. The computer not only controls the pulsations of the discharge but the coincidental inject- ion into the arc of the discrete volumes of the sample solution.Sensitivity, precision, back- ground and interference effects have been studied for some of the easier elements. A new source for trace analysis using two rotating plasmas constrained within a horizontal graphite tube has been developed (605). Improvements in the power of detection by almost an order of magnitude were suggested. Solutions have been studied and the injection of powders is to be attempted in the future. 2.2.2 r.f.and Microwave Plasmas The inductively-coupled plasma has, beyond all doubt, invoked the most interest in instrum- ental analysis for several years. The decision “which system is best ?”-will no doubt cause many emotive arguments both within and without conference halls, lecture theatres, offices and laboratories for some time to come.The first application of this excitation system to analysis was by Greenfield and co-workers in the early 1960’s. A demonstration of a ‘low power’ system was given at the XI1 C.S.I. in Exeter, England in 1965. For those in- tending to use or with an interest in this source unit the new ICP Newsletter, published by The Department of Chemistry of the University of Massachusetts, Amherst, Massa- chusetts 01002 U.S.A., under thc editorship of Barnes provides a worthwhile source of information.Greenfield has published several excellent reviews on the application of ICP’s to analysis (104, 173, 701). The systems used in all these reports have been built “in-house”. The obvious advantages of multi-element analysis with precision and accuracy, claimed by many workers, have quickly been appreciated by many instrument manufacturers.Dahlquist (615, 854) and Davison (741) have attempted to relate the experience gained in pioneering work to industrial analytical requirements. Brech (17, 735) described the application of a new source unit to similar problems. The modern proliferation of abbreviations has extended into this subject, Boumans has used the initials SMEA (Simultaneous-multi-element-analysis) to describe the application of his equipment to the analysis of a variety of solutions.Fassel et ul have reported studies which serve to bridge the gap between academic information and investigation and the practical application of ICP to SMEA (484, 738, 906). The initial promise of an interference-free system claimed in early reports is evaporating like the morning dew in the warming sun as i s illustrated by the work of Mermet (182, 1462) Laison (228) and Koirtyohann (885).The first paper notes the deIeterious effect of Na on Cr and P determinations, in the second, the failure to attain local thermal equilibrium in the plasma causes concern and also contributes conflicting information for the interaction of the same matrix element (Na) on the determination of Cr with addition of data on Ca and Cd.The third paper reports that mineral acid concentrations, in this case HNO,, can alter the results obtained with an ICP. The theoreticians have also been hard at work on this new system. Barnes et af (856) have undertaken computer simulation of processes occuring in the ICP and came to con- clusions concerning the plasmas and their behaviour patterns.The shape of lines in thePart I : Fundamentals and Instrumentation 9 various regions of the plasma tailflame has been investigated and the possibility of ioniz- ation interferences considered. Some of the effects observed in the ICP cannot be explained in terms of the Saha equation.Mermet and Robin (182, 619) have investigated plasmas at two frequencies (619). A microwave helium plasma operating at 2450 MHz has been developed (671) for the analysis of metalloenzymes and up to 10 nm KCL i s used to enhance the line intensities. A high- frequency, high-power source unit at 3000 MIIz has been developed by Van Calker and Hollenberg (643).To date, only the invention of the source is described. An unambiguous comparison of an ICP and a CMP (Capacitively-coupled microwave plasma) has recently been made by Boumans et al (607). It was found that the ICP was a ‘better’ source for practical analysis. The same author found that the most suitable operating conditions for an ICP (1457, 1465) werc a compromise between maximum sensitivity with poor repro- ducibility and good reproducibility but reduced sensitivity, 2.3 GLOW DISCHARGES Hollow-cathode lamps with and without demountable cathodes continue to be used in emission spectrochemical analysis.Very little new work appcars to bc necessary on develop- ing or improving the lamps for AAS, From the series of papers presented at a recent conference one obtains a comprehensive review of the state cf the art.Berneron (588) gives a review of the value of the Grimm Lamp in the analysis of alloys and anaccount (589) of the erosion of metal surfaces by the glow discharge. Lowe (846) has modified the original Grimm lamp by adding a second dischargc at a low voltage by way of an electron- emitting cathode. Aluminium alloys as well as pure metals were investigated.Laqua has provided another excellent review of the work in Dortmund (793) and expresses the opinion that no other single optical emission method has yet offered such a combination of pos- sibilities for analysis. Baudin and Remy (842) suggest that the future for the lamp lies in its value as a atom reservoir for AAS and used a modified Grimm lamp to study diffusion profilcs in flat specimens (849).Gough (838) suggested that the use of the lamp in AAS is best restricted to the detcrrnination of minor constituents in alloys. Cathodic sputtering in AAS studies and observations of the Hank effect (860) suggest that new developments are possible with these discharges. Surface collisions from low-energy heavy-particle bom- bardment of gascs were studied by Folk (794).Measurements of emission radiation from the Grimm lamp have been made by Butler (843). Fabry-Perot interferometers were used by two independent workers to study line-profiles (567, 1312). In the first case, to study the mocsses taking place within the lamp and in the second, isotopic studies of Pb. 2.4 LASERS In spite of the fact that the advantages of laser microspectral analysis have again been stressed for quantitative microanalysis in general (64 1) and forensic analysis in particular (1 330), progress in this field continues to be slow.Generally laser atomizers remain an academic curiosity to many of those engaged in routine analysis. Their high cost and limited range of application relative to other systems has remained an inhibiting factor, It should be emphasised that this may not always be the case if further improvements in laser tech- nology can be achieved.A number of groups (835, 836, 1016) have investigated the use of laser atomization in AAS. Matousek and Orr (835) employed a pulsed infra-red CO, laser with 0.1 J pulses with a width of less than 1 p s and a repetition rate of 5 Hz.Solid, pure-metal samples were containcd in a graphite furnace, but it was found necessary to heat the furnace to a temp-10 Analytical Atomic Spectroscopy craturc just below the threshold for continuous perceptible atom production to obtain satisfactory reproducibility. Others (610, 836) have overcome the problem of inefficient ground state atom production by employing a pulse repetition rate of 100 kHz, which resulted in efficient, quasi-continuous vaporization.Theoretical calculations (1016) carried out for the Cu and Cr lines at 327.4 and 428.9 nm respectively, indicated that detection limits lower than lo-% were unattainable using the total-absorption method and con- ventional procedures for AAS analysis with a laser atomizer. Lacqua and co-workers (836) havc pointed out that laser atomization AAS avoids some of thc shortcomings of spark cross-excitation laser emission methods, such as contamin- ation and dilution problems.However, the same group have investigated the use of micro- wave cross excitation (610, 612, 837), which also serves to overcomc these problems. It was found (612) that incomplete evaporation, short residence time, and rarifaction of the plasma by cross-excitation discharge prevented the detection of masses bclow the picogram level.Using singlc-shot atomization (837) and photoelectric detection, an RSD of about 0.3 was obtained, with detection limits for a number of elcmcnts in Zn in the ppm range. An improved laser micro-spectral analyser (1042) has been described, Cross excitation may be delayed with respect to the laser pulse, or synchronised to it, and a pulse repetition rate of 4 min-1 may be used. Briggs and Kraft (720) have discussed the effect of spectro- graph optical characteristics on laser microprobe emission detection limits.They reported that best results were obtained with the largest aperture instrument used, a 0.75 m f15 spectrograph.A comparison (688) has been made of the relative signal-to-noise ratios of time differentiated photekctric and photographic densitometric recordings of AE from laser-generatcd plasmas. The superiority of the photoelectric technique was less than anticipated. Other references of interest - AE from laser-produced plasmas: 403, 404, 528, 658 Evaporation of solids by laser pulses: 1069, 1070 2.5 FLAMES 2.5.1 Theoretical Studies The results of a number of basic theoretical studies concerned with flame systems which arc pertinent to analytical spectroscopy are reported here.Gaydon (795) has reviewed thc current status of spectroscopic studies on equilibria in flame gases, Frank and Krauss (873) have used a short-duration spark between pure Ca electrodes in a pure oxygen at- mosphere, to study the origin of the green bands of CaO(H). They concluded, from time- resolved experiments which showed that the intensity ratio of the green and orange bands of CaO remains unchanged over a wide temperature range, that hydrogen cannot be a constituent of the emitting species for the green bands which appear, therefore, to originate from CaO.Van Hurk, Hollander and Alkemadc (123, 942) have determined excitation energies of SrOH and BaO bands measured in flames.Excitation energy differences were derived directly from the ratio of thermal-band intensities measured as a function of tem- pcrature. Absorption excitation energies were derived from the temperature dependence of the ratio of thermal-band to atomic line intcnsity under thermal equilibrium conditions using assumed values for the dissociation energy of SrOH and BaO.Flames with temperat- ures between 1907 and 2886 K were employed. Laser Raman spectrometry is finding increasing application in the investigation of flame systems. Setchell(l40) has examined the air/CH, flame by this techniquc and reported zccurate axial and transverse temperature-profile measurements from recorded nitrogenPart I : Fundamentals and Instrumentation 11 spectra.Q-branch bands of CO,, 0, and H, in the flame were recorded; band intensities qualitatively agreed with the concentrations predicted from equilibrium calculations. Ab- solute CO concentrations were determined for rich flames. Arden and co-workers (360) have utilized laser Raman spectroscopy in a study of the gaseous combustion products of flames produced on standard burners for O,/H,, O,/C,H,, O,/CH, and 0, /C,H,.Omenctto (797) has reviewed the possibility of local sensing of physical parameters such as temperature and species concentrations in flames using laser sources. L’Vov and co-workers (1 147) calculated the temperature values and composition of N20/C,H, flames over a wide range of fuelloxidant ratios, The effects of introducing water, changing the pressure and the atomization efficiencies (p) of some refractory elements were also calculated.These studies predict full dissociation of all monoxides except those with dissociation energies (Do) in the range 180-200 kcal mol-1 (B, Ce, Hf, La, Nb, Pr, Ta, Th, U and Zr).Low atomization efficiencies in the air/C,H, flame for elements whose oxides have Do between I30 and 150 kcal mol-1 may be explained by in- complete vaporization of aerosol particles. Stephens and Stevenson have derived a relation- ship bctween CN radical concentration and p of elements introduced into the N,0/C2H2 flame; the relationship has been examined under various experimental conditions and values cstimated for a number of elements (216).The possibility of complcx vapour phase oxide formation by U was discussed. The collisional quenching of elcctronically-excited Sn atoms has been studied by time- resolved AAS (946). Deactivation-rate constants have been reported for quenching of Sn(SID,) with a range of collision partners and the rcsulting data compared with those for analogous states within Group IV (carbon FD, and lcad 67D2).Laniepce (958) has reported measurements of the intensity of the fluorescence radiation (6s 6d)+(6s, 6p), emitted by optically-excited Hg atoms, in the presence of nitrogen. These indicate the order of magnitude of the cross-sections for excitation transfer bctween the (6s, 6d) levels of Hg and for quenching induced by collisions with the nitrogen molecules.An intcrferonictric method based on synchronous scanning of a Fabry-Perot interfero- rncter and a monochromator tuned to select one free spcctral rangc has been developed to measure atomic line profiles in absorption and used to determine the profiles of Ag 328 nm and 338 nm and Cu 325 and 327 nrn in an air/C,H, flame (207).The results have been interpreted in terms of Voigt a-parameters and peak absorption coefficients. The same tech- nique has been applied to determine profiles for these lines from HCLs for calculation of analytical growth curves in AAS in the air/C,H, flame (1416); the effect of lamp current on sensitivity and linearity was studied. L’Vov and co-workers (1340) have measured the shift of the Ca, Sr and Ba lines at 422.7, 460.7 and 553.5 nm respectively emitted by air/ C,H, flames relative to the same lines emitted by HCLs.In agreement with theory the average ratio of shift to the Lorentzian line-width was 0.38. A method for electronic-excitation temperature measurements based on a two-line atomic absorption technique utilizing Pb lines of different lower lev& has been proposed (1294).The absorption of thc Pb 283.3 nm resonance line and the Pb 261.37/261.42 doublet is measured; the method has been applied successfully to the determination of Pb electronic- excitation temperature in an air/C,H, flame and with Ta and glassy carbon strip atomization devices. Held and Stephens (771) have evaluated the effect of photon trapping on line inten- sities observed in AFS and FES.Repeated self-absorption and re-emission of rcsonance radiation at high atom concentration results in trapping, causing a decrease in resonance fluorescence (RF) and an incrcase in direct-line fluorescence (DLF). Equations relating the intensity ratio of DLF and RF in a three-level system to atom concentration are derived12 Analytical Atomic Spectroscopy for atomic vapours at low pressure.The effect of photon trapping on the fluorescence of the Cu resonance line at 325 nm is illustrated. Other references of interest - Low pressure flames: 124, 947. Flame temperature measurements: 120, 1335, 1533. Atomization mechanisms in air/C,H, flame: 242, 435, 867, 1231, 1534. Matrix isolation of reactive metal atoms: 574.Spectra and burning velocity of C,N,/F, flame: 463. Organic solvent flames: 343. Use of AAS in high temperature evaporation and diffusion studies: 308. Mass spectrometry of flame species: 955. Technique for measurement of lifetimes of excited molecular states: 859. Schlicren photography of flames for study of effect of organic solvents: 1302. Role of metastable Na, dimers in theory of induced AF: 468.Flame Chemiluminescence of alkali and alkaline earth halides: 65, 97. 2.5.2 Flame Types and General Studies Koirtyohann and Lichte (1 103) have reviewed the current status of flame spectrophotometric methods for trace analysis and comment that the low cost and ease of operation of these techniques are particularly attractive features and will ensure their continuing popularity.Safety practices for AAS developed by thc Scientific Apparatus Manufacturcrs Association of the USA have been described (49); the items covered include specifications for flame- exhaust systems, rules for safc handling of cylinder gases, conditions for the safe operation of premixed flame burners, precautions in the use of volatile organic solvents and miscel- laneous hazards such as UV radiation and solutions containing cyanide.The application of the premixcd N,O/H, flame to the determination, by AAS and FES, of easily-atomized elements in troublesome organic solvents at trace levels has been recom- mended (890); solvents such as benzene, xylene and gasoline were directly aspirated into this flame with little background signal.In othcr commonly used (hydrocarbon) flames the critical C/O ratio, at which yellow carbon luminescence appears, is easily exceeded with these solvents and background interference is observed. The use of a H,/Cl, flame for AA and emission spectroscopy has been discussed (I 123); it is claimed that the exclusion of 0, from the flame can facilitate the atomization of some elements which produce refractory oxides in conventional flames and detection limits for elements such as Al, As, B, Cs, Cu, Ba, Fc and Si have been presented.Owing to the nature of the products of combustion, HCl, it is doubtful whether this flame would be viable for routine analysis. Held et al. have described a novel flamc “atom trap” system which permits appreciable sensitivity enhancements in AAS for a number of elements (907).In this technique solutions are nebulized into an air/C,H, flame and the vaporized sample is trapped on a cooled surface created by a water-cooled tube placed within the interconal zone; after a suitable period (up to 5 minutes) the sample is released back into the flame by stopping the water flow in the tube and allowing it to be heated by the flame gases.The efficiency, sensitivity and atomization kinetics of the system have been discussed. L’Vov and co-workers (416, 417) calculated the lateral distribution of dry aerosol part- icles in premixed flames from slot burners by the application of Stokes Law to the transport of dry particles in the lateral flow of the flame gases. The effect on lateral flame profiles of the presence of excess concomitants was also discussed.According to the authors the ‘lateral flame profiles’ are more plausibly explained by the transport of aerosol particlesPart I : Fundamentals and Znstrumentation 13 (Koirtyohann and Pickett, A n d . Chern., 1968, 40, 2068) than by diffusion of the vaporized element (West, Fassel and Kniseley, Anal. Chern., 1973, 45, 1586). The same workers have also given a mathcmatical model describing the lateral distribution of atoms in laminar flames from slot burners.The model allows quantitative explanation of observed effects in AAS and the estimation of the maximum possible enhancement by addition of foreign species to the analyte solution. The spatial distributions of the atoms of 16 elements in the N,O/C,H, flame have been dctcrmincd (367) and discussed in relation to the thermody- namic properties of their oxides, Chakrabarti and McNeil (916) have undertaken a similar investigation of the determination of V by AAS in N, and Ar-shielded N20/C,H, flames.Sutton and Lowe (866) have studied the interference effects in AAS produced by a series of mineral acids on B, Zr, Ti, Mo, A1 and V in N,O/C,H, flames.The results yield further information on lateral diffusion effects. Hieftje and co-workers have continued their extensive practical studies concerned with flame spectrometry, The diffusion of atoms and ions from individual solute particles vapor- izing in a laminar flame (752, 1118) has been studied. Direct time-resolved mcasurcmcnt of the spatial atomic-concentration gradient surrounding an individual vaporizing particle is possible.Comparison of these concentration profiles at various times after the onset of vaporization enables the effects of diffusion, vaporization and reactions of analyte with flame gas species to be determined. A flame emission spectrometer with a droplct-generator sample-introduction system (Hieftje and Malmstadt, Anal.Chern., 1968, 40, 1860) has been intcrfaced to a PDP-12/40 computer for data logging, data reduction and real-time optim- ization of the instrument (1 117). The instrument was adaptively optimized to minimize matrix and ionization interferences and to maximise the signal-to-noise ratio. Saturday and Hieftje (1119) reported the devclopment of a modified burner system for use with a pre- mixed H/O,/C,H, flame (see ARAAS, 1974, 4, 8) which overcomes earlier difficulties caused by flashback and thermal deformation of burner components.Hieftje and Bystroff (638) examined the noise power spectra of both background (OH band) and analytc (Na) emission signals from two locations in shielded air/CzIIz flames. Low in the flame, inert gas shielding serves best to minimise flame instability; high in the flame, a quartz scparator proves superior.With the burncrs employed, although no useful high-frequency minima were observed in any of the noise spectra, the presence of strong fluctuations at discrete low frequencies (around 25 Hz) high in the unshieldcd and Ar-shielded flames indicated that these frequency regions should be avoided whenever possible.The existence of an interference mechanism in the N,O/C,H, flame, whereby elements are reduced to carbides so that thcir total vaporization is prevented, has been postulated by Rubeska (1544) and by L’Vov and Orlov (1534). The enhancements observed by refac- tory oxide-forming elements, such as A1 on absorption of Mo or V, are then explained by their prevention of this reduction SO that more complctc vaporization is attained.Rusnakova studied interference effects on Ca, A1 and Si in thc N,O/C,H, flame (1545). The determin- ation of B by atomic absorption and flame emission spectrometry in N,O/H, and N,O/C,H, flame has been studicd (618). Using the B line at 249.8 nm, in AAS the detection limits obtained with these flames were 0.2 pg ml-1 and 2.5 pg ml-1 respectively, while in AES the detection limit in the N,O/H, flame was 0.03 pg ml-1; high flame background prevented emission measurements in the N,O /C,H, flame.The successful determination of B in alloy steels by FES without prior solvent extraction with the N,O/H, flame was reported, Rains and Menis (34) have studied the distribution of the A1 emission at 396.2 nm in the N,0/C,H2 flame using repetitive optical scanning in the derivative mode.This system enabled interferences from CN, CH, and C , band emission to bc ovcrcomc. A detection limit of 0.01 pg ml-1 A1 was reported and the application of the method to the determin-14 Analytical Atomic Spectroscopy ation of A1 in steel, iron, ferrosilicon and phosphate rock samples described.Urbain and Desquesnes (624, 853) have described a differential scanning technique for multi-element analysis by atomic emission spectrometry using two N,O/C,H, flames. The influence of the absorption and emission spectra of the air-C,H, flame on the AA determination of Fe has been investigated (1216). The importance of diffuse parasitic light and the true flame background (band and continuum) on the observed spectra of Na-rich laminar premixcd air/C,H,, air/H, and N,O/C,H, flames has been discussed (217).Thc sensitivity differences in the AAS determination of Cr at 357.87 nm in air/C,H, and air/H, flames for different Cr compounds have been investigated in detail (383). Other workers have also undertaken a detailed study of the determination of Cr in the air/C,H, flame (1564, 1570).Nakahara and Musha have described the determination of In in diffusion flames (1478); the addition of Mg halides was found to be very effective for elimination of interferences (except from Si and V). The same authors have described a similar study for Pb (1378). Fuwa and Haraguchi (656) have recorded the absorption spectra of SO,, PO, InF, InC1, InBr, InO, A1F and A10 in flames when acid or salt solutions were nebulized.It is claimed that some of these spectra can be used for analysis and others are useful for elucidation of atomization mechanisms in the flames employed. Human and Zeegers (636) have observed molecular fluorescence for CaOH, SrOH and BaCl in a O,/Ar/H, flame using a continuum source of radiation.Fluorescence and em- ission spectra were identical; the spcctral distribution of the fluoresccnce emission within a band is independent of the wavelength distribution of the irradiating light, indicating that the absorbcd energy is redistributed before the fluorescence process. The fluorescence efficiencies were determined and found to be of the same order of magnitude as the atomic fluorescence efficiencies.Other references of interest - Solid propellant flamcs: 969. Atom formation review: 796. Chemiluniinescence in FES; review: 498. Effect of acetone vapour in AAS: 166. Absorption tube technique: 91. Atomization systems, reviews: 1056, 1057. Structure of turbulent flames: 1047. Diffusion of atoms in flames: 1166. Non-sclective absorption by metal halides: 345.Flame emission and AAS detectors for chromatography: 72, 135, 224, 889. GC-AAS system for det. of alkyl lead and Se Compounds: 831. Terminology for cool flames: 679, 1252. A1 atomization in O,/N,/H, flame: 868. Sn atomization in H,/air flame: 1391. 2.5.3 Burners and Nebulizers A saEe practice procedurc has been recommended to minimize hazards from flashback of N,O /C,H, flames utilizing a commercially-available burner Fystem and a manual gas- control system; an automatic gas-control unit was also described (312).A number of papers have reported modified burner designs to improve safety and analytical performance, especially for the N,0/C,H2 flame (319, 584, 888). In a comparison of the performance of single and triple-slot air/C,H, burners for AAS it has been demonstrated that only elements with oxides of high dissociation energy show an enhanced sensitivity with the triple-slotPart I : Fundamentals and Instrumentation 15 burner; for elements with oxides of low dissociation energy requiring oxidising flames for analysis, lower sensitivities are frequently observed with the triple-slot burner, possibly due to dilution in its larger flame volume (673).Steiner and co-workers (426) have utilized a modified nebulizer-burner system to study the reactions occurring during the passage of the gaslsample mixture from the nebulizer exit to the burner orifice. Thermometric, gas chromatographic, mass spectrometric and infra-red spectroscopic techniques were employed. The results show differences in temp- erature and pressure of thc gas mixture, which cause change in its composition, at various locations in the system.They confirm that the present arrangcment of the nebulizer- burner system employed makes it impossible to prevent or make adequate adjustments to stabilize these variables. In a Popular Science article entitled ‘Its Superspray’ a method of nebulization using a ‘Babington Nebulizer’ has been described (164).In this device air is passed into a hollow sphere in whose surface there is a small hole or slot. A fine aerosol is produced when sample liquid is passed over the outer surface of the sphere. The air operating pressure is in the range 5 to 20 psi and an aerosol particle size of 2 to Sop1 is claimed; largcr drop- lets can be removed by placing a shroud or impact ball over the outlet of the nebulizer.Further data relating to the analytical performance of this system would be of interest. Rubeska et a2 (11) have described a branched capillary system which allows buffer solutions (LaCl,, KC1 etc.) to be introduced simultancously with the sample solution to a conventional nebulizer. The ratio of the solution flowrates is controlled by the length of the capillaries employed.Ward and Biechler (12) have utilized a similar device to mix a 2000 pg ml-1 Na solution with sample solutions in the dctermination of Ca in natural waters by AAS using a N20/C2H, flame. Taylor (881) has proposed the use of a dual nebulizer to introduce Na solutions separately to overcome the ionization interference of the alkali metals on the determination of K in a premixed air/C,H, flame.Manning (553, 765) has described the advantages of nebulization of small volume samples (100~1) into flames via conventional nebulizer-burner systems. Repeatability was better than that of electrothcrmal systems and was of the order of 0.01 RSD. Samples of high dissolved solid content (e.g. serum) may be handled with little or no dilution without clogging of the burner slot.The technique has been demonstrated by the determination of Cd and Zn in serum and of 11 elements in NBS standard orchard leaves. Thompson and Godden (584) have similarly employed pulsed nebulization of 2OOpl sample solutions in conjunction with use of a high solids N,O/C,H, burner. Other workers (1332) haw optimized the injection method described by Sebastiani et.al (2. Anal. Chem., 1973, 264, 110) to operate with increased sensitivity using 40-loop1 samples. A simple capillary device for reproducible introduction of microlite solution samples into a nebulizer / flame system has been described (1481). Willis has made a detailed study of the feasibility of direct introduction of solids into flames as suspensions of finely ground powder (887, 1239).In this study it was shown that only particles below CQ. 12pm in diameter contribute significantly to the observed absorp- tion and that the atomization efficiency increases rapidly with decrease of particle size. The atomization efficiency, usually only 20 to 40% of that observed with a solution sample, has been found, for a given element, to vary only by a factor of ca. 2 bctwcen rocks and minerals of very different types.Where results correct to within a factor of this order are acceptable the technique avoids the need for time-consuming acid digestion procedures currently used to prepare rock, soil and sediment samples. The use of ultrasonic nebulization techniques continues to attract some interest.In a series of papers, Isaaq and Morgenthalcr have described the performance and application16 Analytical Atomic Spectroscopy of a nebulizer and desolvation system consisting of a commercial ultrasonic nebulizer connected to a temperature controlled hcater in series with a condenser and burner head (1229, 1230, 1238). At optimum conditions of temperature and flow rate the proposed system was found to have a sample efficiency of 85% and a desolvation efficiency of 72%.Sensitivities in AAS comparable to, or better than, those observed with other heated chamber-condenser systems were obtained for a range of elements, The system has good tolerance for solutions of high salt content (1 to 3%); no burner-slot clogging and minimal mcmory effccts were observed.Denton and Gutzler (244) have continued work in FES with a pre-mixed O,/H, flame and have described the use of an ultrasonic nebulizer with this flame. A filter flame emission photometer for the determination of P in air and natural waters via measurement of HPO emission at 526 nm in an air/H, flame has been reported (223); ultrasonic nebulization and an improved burner design in this system are claimed to facilitate a significant improvement in detection limit for P (0.003pg ml-1 H,PO, in aq- ueous solution).Other references of interest - Automated sample preparation: 5 1. Effect of viscosity of petroleum products during FES: 962. Comparison of burners for Zn and Cd AFS: 179. Patents: 75, 296, 970. Burner liquid fuels: 1540. 2.5.4 Other Samplehtroduction Devices Aldous, Mitchell and co-workers haw continued their studies utilizing a modified Delves microsampling cup technique, in which a molybdenum cup and a N,O/C,H, flame is employed (see ARAAS, 1974, 4, 11).The use of this system has been shown (766, 1228) to minimize interferences observed in the determination of elements such as Ag, Cd, Cu, Mn, Pb and Zn; instrument response was indcpendent of sample matrix for both peak absorb- ance and integrated absorbance measurements.The technique has been successfully ap- plied directly to determination of these elements in a variety of matrices. Reports from the same laboratory (573, 761) have also described the use of a similar system for the determination of less volatile elements such as Co, Cr, Mn and Ni.The N,O/C,H, flame gives a high ratc of cup heating and cup temperatures high enough (ca. 1800K) to volat- ilize the less volatile metal compounds. Katskov, Kruglikova and L’Vov (415) have developed an AAS technique for solid samples in which the sample (50mg) i s placed into a porous graphite capsule. The cap- sule is closed with graphite powder, placed horizontally into an air/C,H, or N,O/C,H, flame, and heated electrically.The atomic vapour diffuses through the graphite and its absorption is measured above the capsule; particulate material docs not diffuse and hence no scatter from this source is observed. Detection limits for a wide range of elements bctwaen 10 and 100 ppb have been reported for 40 mg samples. Prudnikov (414) has reported further studies with a graphite rod sampling system in which a T-shaped adaptor and air/C,H, or N,0/C,H2 flame is employed (see AKAAS, 1973, 3, 12).Thermal vaporization of powdered solids, using a d.c. arc between graphite electrodes, and transport of the vapour to premixed flamcs has bccn dcscribcd (1 307). Laser-beam vaporization of nickel-base alloys samples, corundum plates and solution residue on photo- graphic plates was also crnployed similarly in conjunction with an air/C,H, flame.Skogxboe and co-workers (237) have described an interesting technique in which sample injection into flames and microwave plasmas is alTected by conversion of analyte elements to their volatile chlorides which are easily dissociated thermally. 2 pl samples arePart I : Fundamentals and Instrumentation 17 placed in a cuvette within a furnace and dried at 110"; the furnace i s then heated to 850" and HC1 gas passed over the sample.The volatile chloride produced i s then introduced into a flame or plasma and the transient absorption or emission signal measured. Detection limits between 0.05 and 3pg ml-1 level for Sn, Te, Zn, Bi, Cd, Ge, Mo and Pb have been obtained.T h e work of Belcher, Townshend and co-workers with molecular emission cavity analysis (MECA) (see ARAAS, 1974, 4, 11) has continued. Particular attention has been devoted to extension of the capability of the technique for the determination of sulphur (434). The interference from metal ions on the sulphur determination has been shown to be removed by the addition of excess phosphoric acid (921).The technique may be used to determine the composition of mixtures of inorganic sulphur compounds, such as sulp- hide, thiocyanate, sulphite, thiosulphate and sulphate, by the differing time required to achieve maximal S , emission at 384 nm for the different anionic species (872, 1364). Despite the availability of commercial equipment for this technique no other reports of its app- lication have been brought to our attention.Other references of interest - Screw feed for powdcr sample: 1261. MECA: 309, 363, 501, 953. Determination of Bi by candoluminescence: 494. 2.6 ELECTROTHERMAL ATOMIZERS There has been a further decline during 1975 in the number of references dcscribing novel electrothermal atomization systems. Emphasis has been on improving the scope, reliability and precision of the technique using various instrumental and procedural modifications.A considerable amount of work has been performed on the minimisation of interfer- ence effects observed in the analysis of samples; with some impressive results. The emerg- ence for the first time, of a relatively large number of review papers (109, 220, 446, 565, 753, 792, 801, 975, 989, 1011, 1019, 1057, 1171, 1173, 1174, 1195, 1521) would indicate that electrothermal atomizataion has survived infancy and should now progress towards full and long-lasting maturity.The Zn and Fe Contamination of six brands of disposablc pipette tips was studied (13) before and after thorough washing with 1 % V / V HCI. One brand still exhibited appreciable Fe contamination evcn after washing.Unfortunately the brands were not named. Further work on automatic sample injection (803, 1322) has resulted in an RSD of 0.005 for most elements and is thus comparable with the precision obtainable for flame techniques. (See also ARAAS, 1972, 2, Ref 385; 1974, 4, Ref 1530). Massmann and El Gohary (611) have stressed that the measurement of the non- specific background absorption of samples can cause problems when the background ab- sorption is not caused by a dissociation continuum, but results from the complex fine struc- ture of ths electronic absorption spectrum of certain species (e.g.C , OH etc.), (ARAAS, 1973, 3, 17). Other workers (248, 378, 1060) have plotted the absorption spectra of many common species (NaCl, KCl, KI etc.).The spectra were found to be similar to those observed in cool flames; they exhibited more than one peak and were markedly dependent on wave- length. The non-absorbing adjacent line method for correction of background absorption was not recommended. It would be most useful if all of this type of work on background absorption spectra could be tabulatcd in some form.Various instrumental modifications to improve the precision of background correction using a D, or H, lamp have been described (74, 800, 826, 827, 971, 1010, 1221, 1367).18 Analytical Atomic Spectroscopy Further work (770, 799, 1040) has been reported on the use of the Zeeman effect to split resonance lines into pairs of non-absorbing lines in order to correct for background ab- sorption in electrothermal atomization (ARAAS, 1973 3, 4; ARAAS, 1974, 4, 18).An ingenious method of overcoming or considerably minimising the problem of non- specific background absorption was to simply modify the sample matrix by the addition of a suitable reagent (749, 754, 762, 824, 829, 1066, 1468, 1547). For example, if excess NH,NO, is added to a sea-water matrix then, during the dry-ashing phase, NH,C1 is vol- atilized and the residual NaNO, results in a much lowcr background absorption signal than the original NaCl; the addition of excess Ni lessens volatility of As and Se, thus allowing the use of much higher dry-ashing tempcratures; the addition of NH,F, (NH,),, SO, or (NH,), HPO, markedly decreases Cd volatility; the addition of 10% V/V HC10, prevents the formation and premature volatilisation of GeO.Further work has been reported on the formation of pyrolitic graphite coatings by adding a small quantity of CH, to the Ar (or N,) purge gas (83, 110, 121, 134, 177). CH, was preferred to C,H,, C,H, or C,H, (177). These pyrolitic coatings reduce the graphite porosity, improve the precision and sensitivity for a large number of elements and con- siderably improve the lifetime of the graphite element (up to 3 4 times).Considering that this simple technique was reported over two years ago (ARAAS, 1973, 3, 16). it is sur- prising that some manufacturers have not yet modified their equipment or handbooks to allow the use of this technique. Soaking graphite tubes with a 5% m/V solution of Na, WO, was found to improve the sensitivity for Si (702).This improvement was thought to be caused by preferential formation of tungsten carbide (ARAAS, 1973, 3, 17). Other references of interest - Degree of atomization: 317. Drift compensation integrator: 692. Programmed heating: 222. Sample decomposition techniques. 959. 2.6.1 Graphite Rod Devices Torsi and Tessari (246, 247) have reported further theoretical and experimental work on the time resolvcd distribution of atoms in electrothcrmal atomization from a graphite surface (ARAAS, 1974, 4, 13).A theoretical model of thc release and transport of atoms from a graphite surface, under specified thermal perturbation, was developed and found to give good agreement with experimental results. West et a1 (682) have developed an equation showing the rate of evaporation of atoms from a graphite filament.Agreement for this discrepancy were postulated. Winefordner and Chuang (1 382) have described a simple AF spectrophotometer consisting of a graphite rod atomizer and an Eimac Xe between the observed and calculated signal profiles was not always observed and reasons line noise) for Ag, Cd, Pb and Zn were shifted towards higher temperatures in the presence continuum source.The concentration detection limits for Ag, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, T1 and Zn varied from 2 x 10-4 to 10-1 p g ml-1. The various calibration graphs were linear up to concentrations of between 85 and 1000 times the detection limits. Other references of interest- Atomic fluorescence : 121.Interelement effects: 1536. Temperature measurement: 1294. 2.6.2 Graphite Miniature Furnaces Posma et al. (1247) have considered the fundamental aspects of various noise sources asso- ciated with graphite miniature furnaces and it was concluded that the measuring systemPart I : Fundamentals and Instrumentation 19 was shot noise limited. Further work (600) from the same laboratory has described a model for the formation of analytical signals which combined the volatilization model pro- posed by Torsi and Tessari (246, 247) and the basic ideas of L’Vov (ARAAS, 1971, 1, Ref 360).The influence of concentration, heating rate, sheathing gas and the geometrical di- mensions of the device were investigated. It was concluded that there was no correlation between the observed volatility and either the saturated vapour pressure of an element or the dissociation energy of the oxide, chloride or sulphate of the element, The rate deter- mining step was thought to be influenced by interactions between the atoms of the element and the graphite surface.Another study (815) on the “appearance” temperatures of a number of elements under various conditions has been reported.These ‘appearance’ temperatures (in this case defined as the temperature at which the peak height was twice the standard deviation of the base of certain anions (e.g. SO,, PO,), however these anions had no effect on the appearance temperatures of Cr, Cu, Ni and Sn. Again the addition of H, to thc inert gas (757, 816, see ARAAS, 1971 1, Ref 259), was found to improve the sensitivity and reduce the background absorption for a number of elements in a variety of matrices.Johnson and Skogerboe (85) have described a useful device for renewing the contact surfaces of the supporting electrodes on the Varian model 63 flameless atomizer. Other rcfcrences of interest- Background correction: 429, 825, 971.Peak heightlarea: 683. Solid samples: 1164, 1393. 2.6.3 Graphite Tube Furnaces A further study (395) on the development of a kinetic theory of atomization for graphite tube furnaces (ARAAS, 1974, 4, 14) has been reported. Equations were derived for losses occurring during the dry-ashing stage. The advantages of operation under stopped gas-flow conditions and the relative merits of peak height versus peak area measurement were also considered. It was calculated that stopped gas-flow operation could improve peak height by a maximum factor of 2.7 for Cu and that peak area measurement is preferred to peak height measurement when atomization is slow.The optimisation of the instrumental and working conditions for graphite tube furnaces is of prime importance (10, 582, 595, 748, 817) if optimum sensitivity and precision are to be obtained.Unfortunately the degree of improvement was not exprcssly specified in most cases. A number of papers describing emission measurements for graphite tube furnaces have appeared. Such studies were first reported by King (Astrophys I . , 1905, 21, 236). Massmann and Gucer (Spectrochim. Acta., 1974, 29B, 283) have obscrved the emission spectra of some rare-earth elements emitted along the optical axis of a graphite tube fur- nace.Ottaway and Shaw (497, 828) have similarly detected resonance line emission from Ag, Al, Ca, Cu, Cr, K, Li, Mg, Na and Ti. The quoted K an Na detection limits were 1.6 x 10-6 and 2.6 x 10-6 p g ml-1 respectively. However the problem of blanks for these two determinands is a limiting factor.Winefordner et al. (1333) have also detected reson- ance line emission from Cr, K, Li and Sr using both single pulse and continuous nebuliz- ation (in conjunction with a dcsolvation chamber) into a graphite tube furnace. However it was concluded that the absorption technique was superior. It was found (746, 1234) that much lower dry-ashing temperatures could be used for the analysis of biological samples if two rectangular holes (10 x 7mm) were introduced20 Analytical Atomic Spectroscopy at both ends of the graphite tube (each hole located 9 mm from the 2.5 mm diameter sample introduction hole).Adams et al. (756) have used a reduced size graphite tube furnace with a N, purged optical path and vacuum monochromator for the AA determination of I, P and S with some impressive results.The advantages of constant-temperature electrothermal atomizers, where the sample is directly introduced into the heated graphite tube atomizer, have been stressed by various workers (31, 110, 160, 800, 929, 1121, 1195. See also Woodriff, R., Stone, R. W., and Held, A. M., Appl. Spectrosc., 1968, 22, 408). In one case (110) the sample was continuously nebulized into the heated graphitc tube.It was claimed that with continuous nebulization of the sample the precision was improved severalfold, mainly because of a non-transient output signal. The power requirements are somewhat greater than a furnace operated in the conventional transient mode. Herrmann et al. (1464) have determined F by mixing the sample with SiO, and H2S0,.The liberated SiF, was passed into a graphite tube furnace and the Si absorption monitored. Various methods of calibration for the direct analysis of a wide variety of solid samples have been tested (822, 823). Reference materials with a similar matrix to the sample, synthetic solid reference materials, graphite-based standards, solution standards and standard addition were all considered.Gries and Norval (184) have extended their earlier work (ARAAS, 1973, 3, 17) on the preparation of solid calibration standards. These were prepared by direct ion implantation into a mctal matrix or by incorporation of various substances into a urea matrix. Layer by layer analysis of solids by bombardment of the sample with an ion beam followed by adsorption of the sputtered products on the inner surface of a graphite tube was found to be a feasible technique (1006).For a Cu alloy containing 0.01% Ag, a 9 nm layer was the minimum sputtered layer thickness required to detect the Ag. Other references of interest - Atomization mechanisms: 100 1. Collisional broadening: 133. Interference studies: 813, 814, 1205, 1507.Patents: 315, 458, 1210. Peak heightlarea: 632, 684, 813, 818, 819, 908, 910. Rapid heating rate: 1447. Standard addition: 81 3, 964. Thermal diffusion: 64. Vapour-pressure measurement : 344. 2.6.4 Metal Filament Devices Ohta and Suzuki (695) have described an inexpensive Mo microtube atomizer which required a low operating power (4V, 50A). Some results for the analysis of trace metals in rocks after solvent extraction were given. The device would appear to offer no advantage, other than cost, over similar graphitc devices, (see ARAAS, 1974, 4, 16).A patent (70) has bcen granted for a device in which the atomized sample from the electrically-heated metal filament is directed into a silica tube. The device has a low thermal capacity and almost instantaneous response.For Cd, Mg and Zn AA detection limits of less than 50 fg were observed using sample volumes of up t o 1 pl. A similar type of device (1242) has been evaluated €or the analysis of 19 elements in a variety of matrices. For complex matrices (e.g. seawater) electrodeposition was recommended in order to overcome matrix effects (ARAAS, 1974, 4, 16).Part I : Fundamentals and Znstrumentation 21 Interelement effects observed using a tantalum ribbon system have been evaluated Other references of interest - (87) and were found to be very dependent on the operating conditions. Tantalum ribbon: 44, 356. 2.7 OTHER EXCITATION AND ATOMIZING SYSTEMS The analysis of metals and alloys by cathodic sputtering in conjunction with either AA or AF does not appear to have progressed very far despite many favourable claims for this technique (ARAAS, 1973, 3, 19). Amos et al (1145), stressed that the main ad- vantages of the technique lay in the examination of thin coatings and alloys, and for the determination of metals that either require complex dissolution procedures or are poorly atomized in conventional flames. The only new developments in the cold-vapour mercury technique were improvements in the detection limit (1-20 pgHg) using a long path (600 mm) absorption tube (239) and use of the AF technique (310, 633, 923). The main advantages of the fluorescence tech- nique are:-simpler instrumentation using single-beam operation and linear amplifiers (310, 633); reduction in the effect of background absorption; a linear response over a greater range of concentrations. Epstein, Rains and Barnes (1 142) have made an interesting study of the factors influencing precision and accuracy of mercury determinations. Para- meters such as sample preparation, stabilizing agents, analysis time, matrix interference and peak height versus peak area measurement were all considered There have been few new developments in the hydride generation technique. By using a N2/H2 diffusion flame supported on a 10mm i.d. Pyrex tube, and AFS, significant im- provements in detection limits and linear ranges of the calibration graphs were observed for As, Sb, Se and Te (400, 586). As (111) could be selectively determined in the presence of As (V) by buffering the sample to a pH of between 3 and 5 prior to adding the NaBH, (878). Smith (399) has performed a comprehensive interelement study using the sodium borohydride reduction technique. He concluded that group I, JI, ITIA and IVA elemcnts do not interfere, Ag, Au, Co, Cu, Ni, Pd, Pt, Rh, Ru always interfere and that hydride- forming elements mutually interfere. The detection of F compounds from a GLC column has been achieved (20) by mixing the GC effluent with a constant bleed of Na vapour at 800°C and monitoring the Na absorption in a heated silica tube. The presence of F compounds was indicated by a de- crease in the Na absorption signal. An inexpensive combined GLC column and T-shaped heated silica absorption tube (830) have been used to detect Se compounds transpired by Se accumulator plants. Other references of interest - Hydride generation: 428, 691, 880,919, 1217, 1271, 1274, 1508. Mercury: 570, 911, 1317, 1319. RF sputter/AA: 963, 967.

ISSN:0306-1353    

DOI:10.1039/AA9750500006

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

22 Analytical Atomic Spectroscopy 3 optics 3.1 BEAM MANIPULATION Scvcral workers have considered the use of wave length-modulation techniques in emission spectrometry (ARAAS, 1973, 3, 20; 1974, 4, 18). O’Haver et al. (219) have written a detailed review of the use of derivative spectroscopy and have paid particular attention (407, 493) to the use of repetitive scanning techniques for the clirnination of continuum background emission and simple line-overlap interferenccs in a N20/C2H, flame; even when spectral lines were separated by as little as 0.02 nm, avoidance of interelement interferences was possible, although in practice a separation of 0.06 nm was preferred.L’Vov and co-workers (348) have also studied the use of wave-length modulation in emission spectrometry with a N20/C2H2 flame; they found the method to bc especially suitable for working in reduc- ing flames or in regions containing unresolved molecular bands. The design and operational characteristics of a square-wave optical scanning system (1 1 13) have been discussed by Skogerboe and co-workers.Interest in the use of transform techniques in analytical atomic spectrometry has been quite widespread (ARAAS, 1974, 4, 21).Lebedev (1079) concluded, on a theoretical basis, that grille spectrometers may provide a gain in signal-to-noise ratio for detection with a photomultiplier when compared to conventional, non-multiplexed spectrometers. Dawson et al. (578) concluded that when the spectrum under consideration contained only a few intense lines, Hadamard transform tcchniques should give improved precision, but under other conditions, reduced precision of measurement should be expected.In other words, the technique should be advantageous in AA but deleterious for emission techniques. When the technique was applied to the determination of Pb (283.3 nm) and Mg (285.2nm) by FAAS, the detection limits obtained were significantly worse than those obtained using a single fixed slit.A detailed thcorctical treatment (1 324) of the artefacts induced by using a Hadamard mask with transparent slits which arc systematically narrower than the opaque sections of the mask has been published. Malmstadt and Martin (728) have described a non-dispersive flame AF spectrometer for multi-element analysis which utilises frequency multiplexing and demultiplexing by Fourier transform techniques.Several HCLs, each modulated at a different frequency, were used as excitation sources and a solar-blind photomultiplier monitors the optical signal. Applications of Fourier transform techniques to multi-element AFS (977) have also been considcrcd by Fuller. Horlick and co-workers (730) concluded that although spectral measurements in the u.v.-visible region are nonn- ally limited by signal noise (rather than detector noise, where the advantages of Fourier transform are best realised) several important practical advantages should still exist. These are: the precision of thc wave-number axis, the easy control of the resolution function. and the achievement of high resolution in a relatively compact system.In a review of techniques it was concluded (681) that more work and results are necessary to demonstrate the true overall capability of Fourier transform techniques for measurements in the U.V. -visible region. Smythe and Doolan (424) have described a dual-channel, computer-controllcd AF spectrometer which monitored fluorescence-plus-scatter in one channel, and scatter alone in the second channel and thus corrected for the contribution from scatter.A patent (1212) has been granted for a similar design. Other references of interest - Emission mirror adaptor for an AA spectrometer: 335. Automatic frcquency control: 1209.Part I : Fundamentals and Instrumentation 23 3.2 WAVELENGTH SELECTION 3.2.1 Dispers'ive Systems Developments in diRraction grating ruling in Australia (834) have been reviewed and a ruling engine with a piezo-electric inching mechanism described which rules gratings at up to 60 strokeslminute.Westwood and Lit (24) have shown that the resolving power of metallic linear gratings deposited upon a thin-film dielectric waveguide can be increased by separating sections of the grating by blank spaces.Up to 30% higher resolving power may be obtained from such a ruled section grating, even although it has a smaller total number of lines. Pouey (23) discussed the image-forming wavefront given by ruled concave diffraction gratings, using both geometrical optics and diffraction theory to examine their focussing properties. The design of stigmatic monochromators based upon a simple rotation of holographic gratings has also been described by Pouey (25). Bartoe and Brueckner (524) have described the design of a stigmatic, coma-free, concave grating spectrograph which employs double dispersion by two classical concave gratings in tandem.Fassel and co-workers (833, 1101) outlined the problems associated with stray light in ultra-trace determinations by optical emission spectroscopy.Various forms of stray light, originating from grating defects (ghosts, near and far scatter) and from spectrometer design defects were considered, as well as methods for their reduction or elimination. Hodges and Belchcr (1368) have described a method of focussing the zcro-order spectrum from a grating in a direct-reading vacuum spectrometer on the entrance slit of a second monochromator as a method of extending the spectral range to 830nm. A double monochromator (298) incorporating two plane gratings and concave mirrors for collimating and focussing has a lens in front of the exit slit which pivots about an axis parallel to the slit in association with the pivoting move- ment of the gratings and thereby improves resolution and intensity.The various types of quantitative multi-element analysis systems based upon the echelle spectrometer (651) have been critically reviewed. Curry et al. (1 376) have described an automatic filter-posit- ioning device for emission spectroscopy which avoided the need to stop and restart the arc. 3.2.2 Non-dispersive Systems A detailed comparison of signal-to-noise ratios from dispersive and non-dispersive flame A F spectrometers has been reported by Vi.ckers and co-workers (90). It was concluded that non-dispersive systems could not provide any improvement in signal-to-noise ratio and could result in a poorer ratio even for atomizers of quite moderate background emission, such as the separated air/C,H, flame. The development and performancc of a multi-element, non-dispersive AF spectrometer (99) has been described.Computer-con- trolled, pulsed HCLs were used as excitation sources, with a sheathed flame or non-flame atomizer, and computer-controlled synchronous integrators and signal processing. Neville (1 6) critically reviewed the uses and limitations of passive interference filters A Hg-vapour filter based upon a selective specular reflection has been described by Senitzky (152). The filter bandwidth is centred about the Hg 253.65nm line, and can be varied between 0.01 and 0.1 nm by changing the vapour pressure. Effects of spectrograph resolving power: 1041. Modular apparatus for spectroscopy research: 1090. Echelle monochromators: 151 8. Vacuum U.V. spectrometry: 593, 621. Other reference of interest -

ISSN:0306-1353    

DOI:10.1039/AA9750500022

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

24 Analytical A tomic Spectroscopy 4 Detector Systems There has been a significant increase in interest in the potential application of vidicon, TV-type or diode-array detectors for multi-element analysis, resulting, however, in some duplication of effort. Outside this field, very little fundamental work of possible signific- ance in analytical atomic spectrometry has been reported, a notable exception perhaps being the suggested use of photo-ionization detectors (832).Photo-ionization detectors depend upon ionization by far-u.v. radiation of a suitable gas or vapour contained in the detector cell; the ionization current is proportional to the intensity of the incident radiation and is only obtained when the wave-length of thc radiation exceeds the ionization potential of the filler gas or vapour.The detector has been evaluated in a simple non-dispersive micro-wave plasma emission analyser. Tiffany (14) has reviewed the advantages of pyro- electric detectors for the soft X-ray-vacuum U.V. region. Walsh (1046) has suggested the use of a separated flame as a resonance detector. The advantage of this system is the relative ease with which the elcment, to which the detector is selective, may be changed. 4.1 SOLID STATE DETECTORS Duncan (1 5) has described the operating characteristics of typical silicon photodiodes. Photovoltaic operation gave the best signal-to-noise ratio at up to 350kHz, but the photo- conductive mode of operation must be used at highcr frequencies (up to 10ns response time). Neiswander and Plews (1325) reported that a substantial reduction in the noise generated by a silicon photodiode and pre-amplifier may be effected by cooling the system to 200 K.A quantum efficiency at least three times better than that of a photomultiplier was claimed, The use of an anti-reflection coating (1068) to give enhancements of up to 60% in the U.V. response of photodiodes has been described. Drift problems were mini- mised by removal of surface impurities.Fry (1081) has reviewed thc development and uses of photodiode arrays. Horlick and co-workers (89, 485, 654, 744, 1369) have extended their studies of photodiode arrays in multi-element spectroscopy (ARAAS, 1974, 4, Zl), both for AAS (654, 744, 1369) and for d.c. arc cmission spectometry (89, 654). 4.2 VACUUM PHOTOTUBES Pardue (486) and co-workers (471, 652, 11 16) have studied the potential of vidicon spec- trometers, These workers have discusscd the design and performance of a vidicon derivative spectrometer (652, 11 16).Thcy have also used a vidicon spectrometer for simultaneous flame ES analysis for Na and K in serum (471), although this must be classified as a rather extravagant use. A more generally-useful computerised multi-element vidicon flame emission spectrometer (489, 653) has been described by other workers.This spectrometer was used for the multi-element analysis of clinical and geological samples using internal standard- ization in the multi-channel mode. and spectral stripping of interferences caused by flame and concomitant element molecular bands and overlapping lines.Marrs (1 11 5 ) has dis- cussed the use of vidicon tubes in spectrometry and the computer acquisition and treat- ment of data. The slow response of vidicon camera tubes for multi-element analysis renders them unsuitable for the study of transient signals, such as those obtained with certain elcctro- thermal atomizers, Aldous (488) and co-workers (1 128) have reported the results of a preliminary study of the use of an image-dissector multi-channel AA spectrometer.This non-storage image detector may be used to study transient signals. Danielsson et al. (1573) have described a stigmatic, coma-compensated echelle spectrometer incorporating an image dissector tube. A computerised television direct-reader echelle spectrometer has been dev-Part I : Fundamentals and Instrumentation 25 eloped by Wood and co-workers (1377).The instrument operates over the range 230-860 nm, and incorporates an image intensifier for u.v.-visible conversion. The visible light is interfaced with a TV camera. Schagen (1086) and Knapp (131) have discussed the principles of intensifiers, the latter with special reference to flame spectroscopy.Computerised TV spectrometers have been described by Van der Piepen and Classe (591) and Wood, Dargis and Nash (734). It has been shown (105s) that by placing a trans- mission grating over the lens of a TV camera which i s focussed on a source such as flame or discharge tube, simple spectra may be demonstrated for teaching purposes. The nature and applicability of TV-type multi-channel detectors (669, 670) in spec- troscopy has been critically reviewed by Talmi.Other references of interest - Systematic error in microphotometry: 1494. Photographic spectrometry detection limits: 1496. 4.3 SIGNAL PROCESSING The increasing availability of microprocessors may well lead to their more extensive use in commercial instrumentation. Thcy can be used, for example (747, 1125, 1175) to integrate transient absorption signals, to select absorption maxima or to straighten working curves.Witmer (1076) has described a systcm for the automatic analysis of photographically- recorded emission spectra. A semi-classical theory of photon counting for quasi-mono- chromatic thermal (Gaussian) light has been applied by Rures (22) to the calculation of the standard deviation of the photo-electron distribution generated in a detector. For Gaussian light the signal-to-noise ratio equalled the square root of the number of photo- electron events, whereas from pseudo-thermal (partially-coherent) light, the signal-to-noise ratio was approximately equal to the square root of the number of degrees of freedom.Winefordner (487) has discussed the variation in signal-to-noise ratios which may be expected for the various types of multi-element atomic fluorescence spectrometric instru- mentation, including linear and slew scanning, and multi-channel and multiplexed techniques.The theoretical principles underlying the usc of phase-sensitive detection to recover signals buried in noise and the response of narrow band amplifiers to various waveforms was considered by Blair and Sydenham (1083).Faulkner (1082) has published an article concerned with the optimisation of amplifier parameters in relation to those of the signal source, with particular reference to the frequency range d.c. to a few hundred kHz. The physical and mathematical properties of noise and the concepts of noise bandwidth and system bandwidth have been discussed by Usher (1085) and a general design procedure for the fabrication of measurement systems has been outlined. Although these papers were not written with direct reference to analytical spectrometry, the approach adopted is applicable in spectroscopy, and they are therefore of interest lo those involved in synch- ronous amplifier design or evaluation.

ISSN:0306-1353    

DOI:10.1039/AA9750500024

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

26 Analytical A t amic Spectroscopy 5 Data Processing 5.1 EMISSION SPECTROSCOPY Further computerized systems for the spectral analysis of photographic plates have been described (82, 283, 545, 1091, 1109, 1111; see also ARAAS, 1973, 3, 28). In one system (1 1 1 1) a scanning microphotometer controlled by a mini-computer measured transmissions at 5 pm intervals along each spectrum. The device scanned a single spectrum in 70 s, taking over 90,000 readings which were stored in a disc file which could then be searched for up to 500 spectral lines. An integrated intensity method (218) has been devised to improve cornputerised semi- quantitative analysis of geological materials using the d.c.arc. The method was illustrated by the determination of Sr in a Ca matrix, A procedure has been described (235) which used time-sharing coniputer facilities for accurate photographic-emulsion calibration in quantitative work.The operational range was from just above gross fog to very high line- density values. A simple spectral-stripping flame emission vidicon spectrometer has been developed (130) which would simultaneously monitor a 20 nm spectral range.The system effectively overcame practically all the spectral interferences observed in FES. Other references of interest - Book: 453. Calibration: 630, 717, 718, 719, 769, 1036, 1039, 1156. Detection limits: 225. 5.2 ABSORPTION SPECTROSCOPY The interfacing of AA instruments to programmable calculators has been reported by a number of workers (745, 1131, 1329). This type of system allows automatic manipu- lation of analytical results; presentation of mean, RSD and concentration for up to 20 analyses; computation of the analytical results in any chosen units; updating of calibration graphs and computation of peak area (or height) in transient atomization systems.A solid- state computer interface (126) has been used to update older double-beam instruments to give similar performance to the latest models.The factors affecting precision and detection limits have been evaluated (138, 425) for a number of instrumental systems. Shot and flicker noise, readout noise, flame noise and sampling reproducibility were studied. It was concluded that the optimum absorbance range to perform AA measurements depends on the factor that limits the precision (ARAAS, 1974, 4, 22) and is not necessarily the same as that in conventional solution spectrophotometry. Other references of interest - Automation: 451. Calibration: 884. Computer programs: 1172. Electrothermal atomization: 68, 943.

ISSN:0306-1353    

DOI:10.1039/AA9750500026

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

Part I : Fundamentals and Znstrumentation 27 6 Complete Instruments Tables A, B and C contain a comprehensive summary of instruments for analytical atomic spectroscopy. We are indebted to instrument makers for their willing collaboration in the provision of details of their instruments. The tables present information available to us at January 1976. More detailed lists of instrument distributors providing national coverage are available in most countries such as the Instrument Supplement of “Science”, 1975, la0 (November), for America, or the surveys by Krugers published in Them.Weekblad”, 1975, 71 (1088, 1089) for the Netherlands. Over the last two decades atomic spectroscopy has become an established tool in the analytical laboratory. During this growth phase the determination of one element at a time has met the needs of most analysts.The demand for multi-element analyses is in- creasing and obviously if these can be carried out simultaneously there is a saving of time and resources. Simultaneous multi-element analysis by arc and spark techniques is old-established practicc in the spectroscopic laboratory but these methods are unsuitable for the average analytical laboratory.Multi-element AAS has not proved to be amenable to simple instrumentation owing t o the difficulty of providing multi-element light sources and of optimising the instrument performance for each element. Notable reviews on the problems of simultaneous multi-element analysis have been published by Kirkbright (1 190) and Winefordner et al.f1379). As a general solution, the r.f. plasma appears to be the most promising but the successful use of such equipment will require more specialist staff and laboratory facilities than those for flame-based methods. An aspect of analytical atomic spectroscopy which i s not often presented in the scientific literature is the teaching of the subject, therefore the appearance of papers such as that by Price (1191) is particularly welcome.The needs of persons attending an instru- ment manufacturers’ training course, and the problems of designing a course to meet those needs, are considered, The importance of post-training communication by the user with other workers in the field is emphasised. 6.1 EMISSION INSTRUMENTS Two manufacturers appear for the first time in this volume of ARAAS, Kontron of West Germany and Spectroscandia AB of Finland.The former market various direct reading instruments including one using a plasma source and the latter, the IDES universal Spec- trometer with hollow-cathode discharge, d.c. arc and IC sources. MBLE have introduced the Model PV 8350 integrated spectrometer system and an updated range of instruments is available from RSV.Jarrel-Ash have introduced a 50-channel, ICP source spectrometer with computer control and Shimadzu-Seisakusho announced two new direct-readers. A portable flame photometer for the testing of metals has been described (535). The testing head produces a low-voltage arc on the surface of the object and generates an aerosol which is drawn through a hollow anode into the flame photometer for excitation and analysis.The use of a flame photometer for metal testing is unusual as other instruments e.g. the ‘Metascope’ (ARAAS, 1972, 2, 42) have used electrical excitation of the spectrum. Computers are widely used in the control and data processing of more advanced spectrometric systems. A control system for high-resolution echelle grating spectrometer and d.c.argon plasma has been described (1 1 10). Pre-programmed interchangeable cassettes facilitate the use of the system for the sequential or simultaneous determination of 2-20 elements. Other references of interest - Vacuum spectrometer: 1541.28 Analytical Atomic Spectroscopy 6.2 ABSORPTION INSTRUMENTS Many manufacturers have upgraded their instruments: Jarrel-Ash have introduced Dial- atom 111, a single-beam instrument and the 82-850 double-beam with computer-controlled parameters and Czerny-Turner monochromator (747).The Perkin-Elmer 460, a double- beam instrument with Littrow monochromator is micro-processor controlled (1 178), their latest model 40 3 has a Czerny-Turner monochromator and incorporates auto-nitrous oxide switching and burner-head sensor and flame pressure sensor.Instrumentation Laboratory Model 35 1 incorporates push-button controls, auto-calibration and safety gas controls and the Model 451 is a double-beam dual-channel instrument with two Ebert monochromators. Hitachi and Shimadzu-Seisakiishno have also introduced a new range of instruments. To obtain optimum performance of an AAS instrument, time should be spent in determining the effects of changes in gas flows to the burner, the burner height and lamp current.A simplex algorithm has been applied (1383) to factorial optimization of the instrumental parameters in the determination of Ca. This method, however, is more elab- orate than is appropriate in most analytical situations. Trassy and Robin (620) have re- viewed the sources of noise in AAS and describe a dual-wavelength instrument in which absorption measurements were made along the axis of a 40 MHz inductively-coupled plasma generated by a specially designed torch.By correcting for correlated noise in the light source and plasma, this system gave detection limits two orders of magnitude lower for Al, Mg and Ti when used in the two-wavelength mode rathcr than in the normal (single- wavelength) mode.The analysis of biological materials has frequently prompted workers to develop their own instrumentation. For the determination of Ca and Mg in small volumes (approx. 1 nl) by AAS, Danielson (321) has revived the platinum loop technique. An air/H2 flame with adaptor was used to measure 4 x 10-12 moles Mg with an RSD af 0.05. Falchuk et al.(263) developed a multi-channel instrument for the determination of Zn, Cu and Cd. A multi- element HCL and alumina tube, as the absorption cell, were used in conjunction with a concave-grating spectrograph with photomultipliers placed behind exit slits positioned at appropriate points on the Rowland circle. Recommendations of safety practices for AA spectrophotometers have been made (49).These suggestions relate to the gas systems, wastc vessels, the use of organic solvents and eye protection. Other references of interest - AA spectrometer: 1535. 6.3 FLUORESCENCE 1UvS"IRUMENTS At the present time there does not appear to be a commercial instrument availablc for fluorescence analysis. One or two companies offer attachments to AA instruments for selected elements e.g.Hg and those forming volatile halides. A single-element AF spec- trometer has been described by Arnold and Smythe (851). It is a dual-channel instrument in which one channel observes the fluorescence radiation and the second, a nearby non- fluorescence line in order that correction may be made for scatter. The system was evalu- ated for Zn in a matrix of Al,(SO,),.It is claimed that the use of scattering correction lowers the limit of detection by a factor of 10. In the continuing search for simultaneous multi-element analysis instruments, two flame-based computer-controlled systenis have bccn described. In one (727), HCLs are used to excite the fluorescence radiation while in the other (1237), a 500 W Xe arc is used.Detection limits for the latter are claimed to be comparable with those obtained by flame AA.Table A COMMERCIALLY AVAILABLE EMISSION SPECTROMETERS 'a 3 5 Supplier Model channels No. oi $::%:$ nm per mm Wavelength range/nm length Focal Type Of Source Speclal features Appllcrflonr .? ferrous applications f Angstrom Inc., 22-101 D.R. 60 0.278 210-430 3.0 m HV a.c. spark.HV Optical interlock All ferrous and non- P.O. BOX 248, 0.397 210-518 3.0 m or LV a.c. arc, LV spectrum monitor. Bellevllle, 0.556 210-634 3.0 m undirectional d.c. Various excitation stands Mich. 48111, U.S.A. acitor discharge 2 a' arc, triggered cap- and read-out options V-70 D.R. 50 0.556 160-440 1.5 m As model 22-101 As model 22-101. All Ferrous and non-ferrous 3 wavelengths in vacuum.In-focus wavelength geological specimens 3 scanning -t- 3 nm from P, each receiver slit hostile environments. All wavelengths in vacuum. Various read-out options metals, oils, soils and 2 V-71 D.R. 22 0.556 178-320 0-75 m As model 22-101 Mobile and operable in As model V-70 2 excitation stands and 5 $. A-70 D.R. 68 0.556 190-770 1.5 m As model 22-101 As model V-70 As model V-70 but % including determination - of C, S and P A-71 D.R. 22 0.556 210-350 0.75 m As model 22-101 As model V-70 As model A-70 __ ~~ ~ Applied Quanto- D.R. 60 1.388 or 0.695 200-800 0.75 m Low voltage, Air or argon excitation Particularly suited to Research meter 20 (20 lines) 0-695 or 0.35 200-400 high voltage stands. Typewriter and non-ferrous, e.g., Al, Laboratories digital computer options Mg, Cu, Zn and white Ltd ., metals, slags, powders, Wingate Road, solutions, including oils Luton, Beds., England Quanto- D.R. 60 0.70 or 0.35 175-500 0.5 m As Quantovac 80 As Quantovac 80 but As Ouantovac 80, but limited to 28 elements vac 28 (28 lines) no air-conditioner Quanta- D.R. As Quanto- 0.70 or 0.35 175-500 0.5 m As Quantovac 28 Complete computer As Quantovac 28 vac 28C vac 28 control, teletype or visual display output.Off-line computer l i n k s Quanto- D.R. 9s 0.46 170-407 1.0 m Various, low volt- Typewriter, teletype and All ferrous and non- vac 80 (60 lines) age, high voltage, digital computer options. ferrous alloys powders multi-source Single or dual stand including slags, sinters, (HVS, LV, d.c. options. Second stand ores, rocks, ceramdcs, arc) can be argon or air.soils, etc. Solutions, Built-in instrument oils, etc. air-conditioning (con!inued) Quanta- D.R. As Quanto- 0.695 or 0-35 100-610 1.0 m AS Quantovac 80 As Quantovac 80 As Quantovac 80, but meter 80 vac ao excluding determination of C, S and P \o 'New equipment since publication of Volume 4Tablz A COMMERCIALLY AVAILABLE EMISSION SPECTROMETERS- co,nti?iued 8 Applications ( c on1 i n ued ) Quan to- meter 290008 Quanto- meter 33000 Quanto- vac 33000 D.R. 60 0-35 or 0.175 190520 (48 lines) 0.46 or 0-23 190-630 0.56 or 0.28 190-705 0.695 or 0.35 190440 D.R. (64 lines) 0.695 or 0.35 19&610 (8 reference) D.R. k Quanto- 0-46 17O-407 meter 33000 1.5 m A6 Quantovac 80 Typewriter. teletype and As Quantometer 80 digital computer options. Argon and/or air stands available 1.0 m As Quantovac 80 Automated sequential As Quantometer 80 analysis.Computer options also available Computer options also available 1 .O m As Quantovac 80 As Quantometer 33000. As Quantovac 80 Quanto- D.R. As Quanto- 0-695 or 0.35 190-610 1.0 m H.F. plasma Automatic loading of up Solutions 33000CA meter meter 33000 to 24 samples Q.A. 137 D.R. 48 0-46 185410 1.0 m R.F. plasma P.p.b. analysis. Computer Solutions of many (Inductively options also available. materials ferrous/non- coup led ) Direct solids nebuliser ferrous, slags, clinical can be fitted and pollution control applications Baird Atomic Jnc., 125 Middlesex Turnpike, Bed f ord, Mass. 01730, U.S.A. East Street, Braintree, Essex, f ngland Veenkade 26, The Hague, Netherlands SB-1 Phot.- 1.5 or 0.75 370-740 1.5 m Arc or spark Built-In order sorter SH-1 Phot. - 1-0 450-750 1.5 m Arc or spark Built-in order sorter GW-1 Phot. - 0.8 or 0.4 185-2400 2.0 m Arc or spark, Dual gratings for simul- taneous photography of two spectral regions modular or RE-1 GWR-1 Phot. Spectro- D.R. met 1000 30 0-8 or 0-4 185-2400 2.0 m As GW-1 High speed (f/15-5) gratings for rapid exam- ination of transient and/or weak sources of complex spectra.Optional echelie grating for f/12 aperture 0.6 or 0.3 210-590 1.0 m Arc or spark, modular Compact, low-cost direct reader with minimum air-conditioning require- ments. Manual master monitor to check slit alignment General spectrographic analysis General spectrographic General spectrographic 6 analysis 5 analysis 2 E i Transient, weak or complex sources.b General spectrographic analysis 5' $ el -u Ferrous metals (except 3 P 214.9 nm In 2nd order. Non-ferrous metals, oils determination of S) r; using C 193.1 nm, 2 2 0Spectro- D.R. vac 1000 180-3000 3.4 m 180-1 500 180-750 30 spark, low end Unit including high-voltage d.c. arcs. 0 - 6 or 0.3 173-767 1 . 0 m Arc or spark, modu Iar Compact, low-cost direct reader with minimum air-conditioning require- ments.Logarithmic read-out. Manual master monitor to check slit alignment. Dual stand option Ferrous and non-ferrous, including C, S and P Spectro- D.R. met II 0.294 180-432 2.0 r.: As Spectromet Automatic optical servo 0.59 190-863 1000 monitor continuously maintains correct slit alignment.Logarithmic read-out. Manual master monitor to check slit alignment. Temperature- compensated fixed focal length. Dual stands for argon and air available All direct-reader applications above 190 nm Spectra- D.R. 60 0.29 17-32 2-0 m As Spectromet As Spectromet II. All vac I! 1000 photomultipliers in vacuum All direct-reader applications including C, P and S Jarrell-As h Div., Fisher Scientific Co.. 590 Lincoln St., Waltham, Mass. 02154, U.S.A. Fisher Scientific Co., Jarrell-Ash Division Europe, Av de Lavaux 26 1009 Lausanne- Pully, Switzerland Fisher Scientific Co., GMBH. 78-000 70-31 0 75-1 50 SO-750 90-785 1500 70-314 Phot. Phot. Phot . O.R. D.R. D.R. D.R. - 1.1 or 0.54 Wadsworth Spectrograph General spectrographfc an a I y s i s General spectrographic ana I ysis - 1.0 to 0.24 depending upon grating 20 inch camera 4.4 t o 1 * 3 3.2 to 0-8 1-6 to 0.4 Choice of 3 gratlngs.Nitrogen purging extends range to 175 nm. Optional accessories permit use as direct reader or scanning spectrometer Versatile instrument particularly suitable for measuring transient spectra Up to 50 0.54 Up to 50 0.54 As above, except Computer controlled electronic con- trolled peak current As above Choice of 2 gratings Most metallurgical analyses Up t o 30 0.56 or 0.28 0-34 or 0.17 1 30+ As70-310 200-800 or 1.5 m 200-510 or ) 190-250 As 70-310 3.4 m 190-400 i All direct-reader appiicatlons above 190 nm Heilgerweg, 67/69 46 Dortmund W Germany Nip pon J arr e I- Ash Co.Ltd., Kyoto, Japan As above Scanning optional. Easy interchange to photo- graphic (70-310) and scanning version (70-320) 1 Variable Channel lCAP Computer controlled All direct-reader applications above 190 nm (continued) Up to 50 0.5 168-500 0-75m All solutions +New equipment since publication of Volume 4Table A COMMERCIALLY AVAILABLE EMISSION SPECTROMEERS- corttinued Reciprocal No’ Ot dispersion/ Wave’ength E:k Type of source Special features Supplier Type channels nm per mm range/nm Applicatlons (continued ) 84-405 82-410 82415 82-000 25-100 75-150 Scan - 3.3 1.6 and 3.3 Scan - Scan - Depends on grating Scan - As above Scan - As above Scan - As above 200-900 0.25 m None 200-900 0.25 m Tungsten Depends on 0.25 m As above Deuterium grating selected As above 0 - 5 m Supplied As above 0.75 m, As above 1.0 m 2.0 m by user As above 0.75 m, As above 1.0 m 2.0 m Various scanning Suitable for spectro- spectrometers scopic investigations rather than for analytical applications Jobin-Yvon VARAF Scan.- Division d’lnstruments SA, 16-18 Rue du Canal, 91160 Longjumeau, France DELTA Scan. - 1.8 or 0.9 200-800 0.465 m Flame Czerny-Turner mono- Liquids and solutions chromator, adjustable bandwidth 0.024 nm. Nine models with various burner and read-out opti ons Czerny-Turner.mono- Liquids and solutions c hrom at or, ad] us t a b le bandwidth 0.02-4 nm.Automatic wavelength scannina device. 1.2 195-770 0.6m Flame Pneumaiic nebuliser, laminar flow burner. UI tr as o ni c ne buli ser optional tabtes t 310 D.R. 60 0.56 190-900 1.5 m ‘Transource’ Wavelength in first order. Ferrous and non-ferrous Equipment Co., high voltage CRT.Teletype printer or alloys 11 826 La Grange triggered computer readout Ave., V-25 D.R. 40 0.67 170-550 1.0 rn discharge. Law systems, dual air/inert As above Los Angeles, voltage triggered gas and solution excita- Calif. 90025. 2100 D.R. 30 0-46 188455 1-Om d.c. arc tion stand As above U.S.A. 71 D.R. 74 0.52 170-900 2.0m General purposeKontron, GmbH, 2100* D.R. 28 0051 Eching b, Mimchen, V25* D.R. 42 0 s kar-von- Miller-Str. 1, 310' D.R. 60 West Germany ICP* 40 Plasmaspec 100 1.0 m 1.0 m 1.5 m Plasma Steel, slag, cement, rock, soil, noble metals, plating liquors, food, sewage, blood M.B.L.E.. PV83M) D.R. Rue des Vacuum Deux-Gares, 80 6-1070, Brussels, Belg i um Pye Unicam PV 8350' D.R. Ltd.. Vacuum York Street, Cambridge, CB1 ZPX, England PV8210 D.R.Air 60 0-55 170-430 1.5 m Triggered capac- 0.46 Monoalterance' discharges up to 500 Hz. d.c. arc intermittent arc (80 lines) or !tor discharge. 20 0.46 177-410 1 m AsforPV300 0-55 190-700 1.5 m As for PV 8300 0.28 or 6.0 (50 lines) Optional dual air/argon Steels, iron, non-ferrous excitation stand. Readout metals and non- by printer, teletype or conductive powders digital computer systems Air stand for oils, d.c.arc, etc. Integrated spectrometer Steels, iron, non-ferrous system including source metals, non-conductive and read-out options as powders for PV 8300 Wavelength range All direct reader covered in 1st crder. analyses above 190 nm Remote-controlled particularly non-ferrous roving detector. metals, solutions, oils External excitation.and non-conductive Rotrode and inert powders atmosphere facilities Readout as PV 8300 Optica, 65 Phot. - 0.69-0.36 200-800 1.2m Via Gargano, 21 20139 Milano, Italy B5C D.R. 16 0.69 or0-36 220-420 1.2 m B7V D.R. 93 0.37 165-440 1 - 5 m (continued) All conventional types available LV triggered arc and spark. HV spark, a.c. and d.c. arc LV triggered arc and spark. HV spark Stigmatic instrument with rotating Ebert grating General purpose Double spark stand both in air and inert atmostphere. Rotrode for solutions Air-vacuum instrument with all 92 exit slits accessible from outside for adjustment.Many analytical programmes can be arranged in parallel for easy inter- change. Computer facilities available. General purpose. Metallurgical analysis, e.g., Al, Pb.Zn, Fe. Cu alloys. Wear metals in oils etc. Complex analyses involving many spectral lines *New equipment since publication of VOSUme 4Table A COMMERCIALLY AVAILABLE EMISSION SPECTROMETERS - continued Reciprocal No- dlsperBlon/ Wm'len@h Type of source Special features Appllcations Suppller Yodel 'me channels nm Der mm rrnge/nm Metallurgical work. All material excitable with same source parameter Controlled and Scanning monochromator non-controlled HV with one channel for spark, a.c.arc analytical line and another channel for reference using reflected beam principle ESA1 Scan. - 0.41 200-500 1.0m (continued 1 ESA3 D.A. 9 f Scan LV triggered arc and spark and polychrornator. A l l Combined vacuum mono- excitable elements accessible with scannlng system LV triggered arc.Scanning vacuum mono- HV spark, a.c. arc chramator with one channel for analytical line and another channel for reference. Facilities far analysing two elements simukaneously Routine analysis (including C, S and P) of iron and steel. Non-ferrous alloys 0.36 160500 1-2 m (40 nm as POfY- c hromat or) ESA4 Scan. 0.41 165500 1.0m Metallurglcal work. Analysis of ferrous and non-ferrous alloys Ferrous and non-ferrous alloys. Geological samples.Wear metals in oil Ferrous and non-ferrous alloys. Wear metals in oils Rank Hilger El000 D.R. 60 0.293-1.155 159,64644 1.5 rn Various, including Duel $Dark stands. Westwood Po I yvac high repetition Industrial condensed arc Compuier-control led instrument. Dual grat- ings give 7 systems Estate, Margate, Kent, CT9 4JL England EQ52 D.R. 36 0.546ar 174.0-447-7 0.75m As ElOOO 0.741 Curved entrance and exit slits. Solid state erectronics or compu!er controlled. Air or vacuum Adlustable slit. Spectral length 0.67 m, of which 0.24 m can be selected for a given exposure €74213 Phot. Large Quartz/ Glass - 191-800 1.57 m D.C. arc, HV Bpark condensed arc Analysis of high-purity specimens having complex spectra.Determinations of trace element concentrations Routine qualitative and quantitative analysis. Flash photolysis. Examinetion of line profiles Non-ferrous metals, scrils, additives and wear metals in oils b E777/8 Phot. 0.26-0.97 200-1200 1.5 m Various Czerny-Turner mono- chr omat or €549 D.R. Medium Quartz 0.5-10 200-600 0-53 rn HV spark, con- densed arc, d.c. arc, t hyratron- controlled a.c.arc Solid state electronics. Quartz plate for atmospheric pressure compensation 12RSV- SPN 3.5 Phot. Prazisions- D.R. mehgerate, GmbH., 8031 Hechendorf Pi Isensee, West Germany Siemens Ltd., SPN 2.0 Phot. Great West D.R. House, Great West Road, SPN 1.5 Phot. Brentf ord, D.R. Middlesex, England SPN 1.0 Phot. SPN 1.0 Phot. Analymat D.R. {vat) I-air 30 30 15 - I 40 40 40 250 250 250 Scan Scan Scan 0.14-0.48 200-1000 3.5 m Glow discharge Paschen-Runge mounting General analysis lamp.high, speclally designed for medium or low voltase spark, a.c. Direct reading attach- range below 200 nm. or d.c. arc, continuous end intermittent ment available 0.24-0.84 200-1000 2-01-17 Asabove As above As above 0.37-1 * 1 200-1 000 1.5 m As above As above As above 0.56-1-7 200-1000 0-4-1 -7 300-1300 1.0 m Asabove 1.0 m As above As above As above As above As above 0.31 orO.54 200650 1.5 m Glow dlscharge lamp (others available) Exhibits no background: As above no matrix effects.Linear calibration for all elements 0-100% As above As above Analymat D.R. Analymat D.R. Analymat" D.R. I I-vac I I I-vac I V 0.31 or 0.54 150-490 1.5m Asabove 0-42 or 0.5 110500 1.0m Asabove As above As above 0.22 2x 2x2.5m 200-630 As above 2X As above 2X spectrum length 150-600 120-630 0.16 200-630 2-Om As above As above As above Analymat* D.R.V 2.0m As above As above As above Analymat* D.R. VI 2.0m As above As above As above Analymeter* I 2.0m Asabove As above As above Analyme?er* I I Analymet er Ill 0.16 15G6-630 2.0 m As above As above As above 0-16 11W3-630 2.0 m As above As above As above S hi madzu GCT-100 Photo 3 0.83 200-850 1-0 m Modular-source High speed Seisakusho Ltd., (Czerny & & D.R.(max) (1200 Gjmm) (10" camera) DCA, ACA 1 Nishinokyo- Turner) LVS, LVA Kuwabaracho, Nakagyo-ku, GE-170 PhOlO - 0.48 200-1200 1 - 7 m HVS Kyoto, (Eberl) (1200 G/mrn) (10" camera) S DCA Japan GEW-170* Pho:o 55 0.48 200-1200 1.7 m (continued) (Ebert) 8 D.R.(max) (1200 G/mm) (20" camera) General purpose General purpose *New equipment since publication of Volume 4Table A COMMERCIALLY AVAILABLE EMISSION SPECTROMETERS - coritirzued w Q\ Reciprocal 'Om Of dispersion/ Wavelength &zk Type of source Special features Applications Supplier Model Type channels nm per mm range/nm - (continued) GQM-75' D.R. 35 0.52 190-430 0.75 m HVS, LVS 1 3 kinds of read out General purpose electronics are available 1.Computer built-in 2. Digital with linearizer 3. Pen recorder Solid, liquid, powder Metal Optimised AE system Routine analysis and a high temperature I multi-element analysis using a high dispersion high energy throughput echelle spectrometer Routine quantitative plasma jet excitation source 1 (max) (2400 G/mm) & 510.5 DCA 589.0, SG-400 518.3 GVM-100 D.R. 60 0.46 170410 1 . 0 m HVS, LVS (max) SG-400 \ 1 Spectrametrics AE 2 Phot. 1 0.06 19B-900 0.75 m Plasma jet Inc., D.R. 204 Andover St., Andover, D.R.10 D.R. 20 0.06 190-900 Plasma jet Mass. 01810, (inter- U.S.A. changeable c assett es ) Techmation ES 9 Phot. - 0.06 19C900 0.75 m Plasma jet, flame Built-in computer Ltd., or arc stand 58 Edgware Qualitative and semi- Way, Edgware, RS 1 D.R. 1 0.06 190-900 0.75 m Plasma jet, flame quantitative analysis. Middlesex (variable or arc stand Spectroscopic research HA8 8JP, wave length 1 England Spectra- Phot 20 Element 0.06 190-900 0.75 m d.c. argon Optimised AE system Routine sequential. span I l l * D.R. inter- Plasma using high-dispersion Quantitative analysis changeable high energy throughput and multi-element cassettes echelle grating spectra- analysis meter and a high- temperature plasma jet excitation source. Built-in micro-processor.Most spectral and matrix effects are eliminated. G 2. - 1.6 175-1280 0-5 m - Multi-purpose unit Routine analysis - 1.1 175-1500 0.75 m - - Research s.Spex Industries 1870 Scan. Inc., 3880 Park Am., 1702 Phot. Metuchen, U S.A. N.J. 08840, 1704 Phot. - 0.8 175-1500 1.0m - - Research $ $ 3 Direct reading Routine analysis 5' - 0.8 180-1500 1 . 0 m - 1802 Phot. Glen Creston, accessory available The Red House, 37 The Broad way, St anm ore, Middlesex England ? 2 HA7 4DL, 2 87 Spectroscandia IDES* D.R. 100 0-16 at 200 200-800 0.5 m Hollow cathode Channels not preselected, Ferrous and non-ferrous AB, 2080 (300 lines) 0-32 at 400 discharge, plasma, changeable at anytime. metals, slags, powders, 5 Finland 0.63 at 800 0.2 nm.Wavelength specimens, trace accuracy 0.001 nm Plane samples crganic materials and $ 0.8 to 0.1 crn. CRT Lineprinter or Teletype readouts. Digital computer as - ~~ ~ ~ _ _ ~~ _~~ SF-21660 Nagu, 0.52 at 650 d.c.arc Channel minimum spacing ores, geological .? 2 standard 9 3 elements in metal, solutians. High accuracy in low and high concentrations 3 VEB Carl Zeiss PGS-2 Phot. - 0-74 or 0.37 200-2800 2.075 m Arc or spark Automatic expansion of General spectrographic 2 Jena, measuring range. analysis. Also examina- A 69 Jena. Stigmatic depiction. tion of line profiles, Dispersion doubled by hyperfine structure etc.rs 2 Carl-hiss Str. 1, German double passage of light. "c Democratic Pre-disperser for order Republic sorting and isolation. s Carl Zeiss Automatic transport of Scientific Instruments Ltd., Full range of General spectrographic PO Box 43, accessories available analysis 2 Elstree Way, Boreham Wood, Herb, WD6 1NH E ng 1 and Qratings interchangeable. "c plate holder 2 -.Q-24 Phot. 0.76 210550 0.54 m Arc of spark "New equipment since publication of Volume 4 w 4w Table B COMMERCIALLY AVAILABLE ATOMIC ABSORPTION SPECTROMETERS 00 Single/ Supplier Model double Yonochromator *x? i$?sg$ W.ve’ength Other features beam uer mm nm per mm ‘ame/nm exmnsion Beckman Instruments, 485 Double Littrow 1200 2.7 0.2 190-860 Meter: x 50 Single and triple pass 2500 Harbor Boulevard, optics: automatic filter Fullerton, Calif. 92634, se lec tfon U.S.A. 495 Double Littrow 1200 2-7 0.2 190-860 Digital; x 100 As model 485 Beckman Instrument GmbH, 1233 Double Littrow 1200 2-7 0.2 190-860 Meter: x 55 Single and triple-pass 8 Munich 45, Frankfurter Ring 115, concn. read-out West Qermany 1236 Double Littrow 1200 2.7 0.2 160-860 Digital; x 55 As model 1233 optics; % T, abs.or Beckman RllC Ltd., Eastfield Industrial Estate, 1248 Double Littrow 1200 2.7 0.2 190-860 Meter: x 10 Auto zero and calibrate Glenrothes. Fife, integration KY7 4NG, Scotland 1272 Double Littrow 1200 2.7 0.2 190-860 Digital; x 10 As model 1248 pfus curvature correction Carl Zelss, FMD 3 Single Ebert 7082 Oberkochen, Wurttem berg, West Germany 600 2.5 0.05 193-300 Digital 4-lamp turret, 2 stabilited power supplies.Curve correction, auto zero, optionat auto calibrate and background correction Corning Ltd ., Halstead, Essex, CO9 2DX EEL 140 Single 0.25 m modified 1180 3.5 EEL 240 Single As EEL 140 1180 3.5 Ebert-Fast ie Non-linear Single-lamp turret meter Meter 4-lamp turret; integration Diano Corporation, Multi- Single Double grating 1200 1.5 0.2 190-800 Meter; x 10 %lamp turret with 3 9, 75 Forbes Boulevard. spec 0.25 m modifled stabilized power sup lies; ‘1, Czerny-Turner 4-way gas control; ZT, ;i- Mansfield.Mass. 02048, U.S.A. abs. or concn. read-out a, ~ ~ GCA/McPherson Instrument, 530 Main St., Acton, Mass. 01720, U.S.A. Hitachi Ltd.. Nissei Sangyo Co. Ltd., 7 5-1 2 Nishi-S him bas hi, 2 4 home, Mi na t o-Ku , Tokyo, Japan ~- ~~ EU 703 Single 1180 2.0 ~~ ~~~ ~~~~ 0.1 180-1 100 Digilal Modular AA; flame emission; various detectors and grating available; convertible to single or double beam UV spectrometer 170-1 0‘ Single Littrow 7 440 2-25 0.4 7 90-900 Meter: Single, N,O-air x 0.1- x 1 x 1- x 10 Digital: continuously variable (Optional) time constant simultaneously exchanged Concentration read-out170-30' Single Litlrow 176-50' Doub!a Littrow 1440 2.25 1440 2.25 0.4 0.1 190-900 As 170-10 Concentration read-out, time weighted.Averaging Signal AA/A& measure- ment auto zero. N,O-Air simultaneously exchange Base line drift correction. Curve corrector time weighted. Averaging signal, auto zero 190-900 As 170-70 Background correction.Instrumentation Laboratory lnc.. 113 Hartwell Av., Lexington, Mass. 02173, USA Instrumentation Laboratory (UK) Ltd., Technical Services Div., Edgeley Rd. Trading Estate, Cheadle Heath, Stockport, SK3 OXE, England 351" Double 0.33 m Ebert 1200 2.5 0.03 190-900 251 Double 0.33 m Ebert 1200 2.5 0.03 151 Single As251 190-900 Digital: 4 lamp turret, wavelength x 5 0 drive, full time integration peak height or peak area. Auto- calibration, curve correction, background correction, dual-grating.Push button operation- zoom fens. Full automatic safety gas controls. 4 lamp turret, wavelength integration, peak height or peak.area, off line calibration, curve correction, background correction, zoom lens, au tog a s Digital: X 50 drive, full time Jarrel-Ash Division Fisher Scientific Co., 590 Lincoln St., Waltham, Mass. 02154 USA Fisher Scientific Co., Jarrel-Ash Division Europe, Av-de Lavaux 26, 1009 Lausanne-Pully, Switzerland Fisher Scientific Co. GrnbH, Heilgerweg 67/69, 46 Dortmund, W Germany Dial' Single 0-25 m Czerny- 1 t80 Atom Turner I l l 82-810 Double 0 . 4 m Ebert 1180 dual channel 82-850 Double 0.4 m Cterny- 1180 Turner 3.3 0.02 193-860 Digital Laminar flow burner, integral gas flow controls auto-zero, concentration calibration, curvature correction: 2 lamp turret 2.08 0.C3 19D--WU Digital: Laminar flow burner, x 25 curvature correction. 2.08 0.03 190-900 Digital Cornp uter-contr ol led 2 lamp turret parameters 'New equipment since publication of Volume 4Table B COMMERCIALLY AVAILABLE ATOMIC ABSORPTION SPECTROMETERS - continued Supplier Single/ Oratha Reciprocal Resolution Wavelength Read-out; Other features range/nm Model double Monochromator lines dlsperaton/ nm beam per mm nm per mm Jobin-Yvon, VARAF Single 0.465 m 1220 1.8 Division d ' I ns!r ument s , 16-18 Rue du Canal, 911 60 Longjumeau. France Czer ny-Tur ner Digital Optica, Via Gargano 21, 20139 Milano, Italy 6000 Single 0.35 m Ebert Digital; x 50 Auto filter insertion, auto concn., integration.Flame temp. regulation. Pre- focussed water-cooled hollow-cathode lamps available Perkin-Elmer Corp., 103 Single 0.27 m Littrow 1800 1.6 0.2 Norwalk, Conn. 06856, U.S.A. Perkin-Elmer Ltd., 107 Single 0.27 m Littrow 1800 1.6 0.2 Post Office Lane, Beaconsfield, 360 Double 0.27 m Littrow 1800 1.6 0.2 Bucks.HP9 lQA, England 370 Double 0.27 m Littrow 1800 1-6 460' Double 0.27 m Littrow 1600 1.6 0.2 0.2 306 Double 0 - 4 m Czerny- U.Y. 2860 0.65 0.03 Turner vis. 1440 1.3 190-860 Meter; x 50 190-860 Digitd; x 50 190-860 Meter: x 50 190-860 Digital; x 50 and x 0.5 All mirror optics; integration: auto zero and flame ignition As Model 103 All mirror optics; auto zero, gain control, flame ignition and optiona! nitrous oxide switching; integration; curve correction: peak reader As model 360 190--860 Digital: All mirror optics, micro- auto zero, auto concentration, automatic gain control, auto curve correction with up to 3 standards, peak height, peak area, integration time selectable from 0.2 to 6.0 seconds, flame ignition, auto nitrous oxide switching, optional double beam background correction 18(1-440 Digital; All-mirror optics; auto 400-900 x 0-1-x 100 zero and flame ignition: peak reader; integration; curve correction; auto concn.x 0.01- x 100 processor controlled,503 Double 0.4 m Czerny- Turner U.V. 2880 vis. 1440 0-65 1-3 0.03 180440 400-900 Digital; x 0.1-100 603' Double 0.4 m Czerny- U.V. 2880 0.65 0.03 180-440 Digital: Turner vis. 1440 1-3 400-900 0.01-X 100 As Model 306 plus signal averaging: auto nltrous oxide switching; flame, pressure and burner head sensors All mirror optic micro- processor controlled, auto zero, peak height peak area, integration times from 0.2 to 6 - 0 seconds, auto concentration, auto curve correction with up to 3 standard flame ignition, auto nitrous oxide switching burner head sensor, flame and pressure sensor Bodenseewerk 4005 Double 0.33m Crerny- 1800 1.3 0.2 190-860 Meter; x 50 Auto zero and flame Perkin-Elmer 8 Co.GmbH, Turner and x 0.2 ignitlon; Integration Postfach 1120, D-7770 Uberlingen. 400 Doubla 0.33 m Crerny- ls00 1-3 0.2 190-960 Digital; x 50 As Model 400s plus auto West Germany Turner and x 0.2 concn.: curve correction PysUnicam Ltd., SP 191 Single EbM 1200 3-3 0-2 19-50 Digital: x 25 4-lamp twek auto zero Ywk Street, and x 0.1 and ignition: integration; Cambridge, CB1 2PX, curve correction England SP 190 Single Ebert 1200 3.3 0.2 190-850 Digital; X 25 As Model 191 without SP 1950 Double E M 1800 2.2 0-1 19M50 Digital: x 20 Auto zero and ignltion: and x 0.1 emission capablllty and x 0.1 integratlon; curve correctlon SP1900 Double Eberl 1800 2.2 0- t 190-850 Digltal; x 20 As Model 1950 plus and x 0.1 &lamp turret Ran k-Hi Iger, ATOM- Single Silica prism - 1 -7 at Westwood Industrial Estate, SPEK 200 nm Ramsjale Road.H 1170 44.8 at Margate, Kent, CT9 4JL. 500 nm Meter 6- lamp t unet England ATOM- Single Czerny-turner 1200 2.0 0.1 190-850 Dlgltal 6-lamp turret; auto zero SPEK and flame ignition; H 1550 curve correction; integration, background correction opt iona I *New equipment since publication of Volume 48 - Table B COMMERCIALLY AVAILABLE ATOMIC ABSORPTION SPECTROMETERS - continued Selko Instruments, SAS 721 Slnale Tokyo, Japan SAS 740 rouble; dual channel Microcomputer and line printer Shandon Southern A3400 Single 0.25m Czerny- 632 6.0 0.2 190-860 Meter: x 25 4-lamp turret: auto zero Instruments Ltd., Turner and flame ignition; curve Frlmfey Road, Camberley, correction: integration Surrey, GU16 5Ef, England wavelength scan Shandon Labortechnik A3600 Single 0.25 m Czerny- 632 6-0 0.2 190-860 Meter; x 25 Integration GmbH, Turner FrankturtIMain 50, West Germany Shimadzu-Seisakusho Ltd., AA-6105 Single Czerny-Turner 1500 1.9 Kyoto 604, Japan AA-620* Single Crerny-Turner 1500 1-9 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, AA-650' Double Czerny-Turner 1200 1.9 19D-900 Meter: x 10 Wavelength drive, two lamp holders 190-900 Meter: x 10 Wavelength, drive, two lamp holders, auto ignition, flame monitor, gas pressure monitor 190-900 Digital: x 180 Wavelength drive, two lamp holders, auto zero integration, curvature correction, BG correction, peak detector, auto ignition, flame monitor, gas pressure rn on i tor Varian Techtron Pty., llOa/ Single 0.25 m Czerny- 1276 2-8 0.2 185-900 Meter/ &lamp turret, auto zero, 679 Springvale Road, 1200 Turner Digiiel; Mulgrave, Vic. 3170, x 0.3-x 50 correction, peak reader. Australia f/8 aperture, optional inlegration, curve ;i' 4 automatic gas-box Varian Associates Ltd., $ Russell House, 1150/ Single: 0.25 m Czerny- 1276 2.8 0.2 185-900 Meter/ As Models 1100/1200 Molesey Road, 1250 dual Turner Digital; plus simultaneous Walton on Thames, channel x 0.3-x 50 background correction, 2 Surrey, England optional automatic gas box on Model 1250Varian Instrument Div., 611 Hansen Way, Palo Alto, Cafif. 94303, U.S.A. AA6 Single; 0.51 m Ebert dual channel 638 3.3 0.05 'a x 0-3-x 50 correction, iniegra:ion, ? crl 185-1000 Meter/ Modular construction digital; 4-lamp turret, auto curve 2 peak reader, f/10 aperture, optional automatic gas-box and simultaneous background correction ' 3 VEB Carl Zeiss Jena, AAS 1 Single 0.5 Ebert 1300 1.5 Continuously 190-820 Meter; x 10 4:lamp turret, auto zero, ij 6 69 Jena, adjustable single or triple pass Carl-ZeissStr. 1, optics, continuously German Democratic Aepu bl ic R adjustable slit 2 2 Elstree Way, 2 3 2 !3. C 2 instruments Ltd. Boreham Wood, Herts WD6 lNH, England 3 *New equipment since publication of Volume 4 P wTable C COMMERCIALLY AVAILABLE ELECTROTHERMAL ATOMIZERS t - . c u si Barnes Engineering Co., Q lomax Tantalum strip 50 Programmable; d.1. 10-11 g N.S. Fits most AA spectro- 30 Commerce Road, dry, ash, atomize, (50 PI) meters.Air-cooled; inert- Stamford, burn off. Max. gas and hydrogen Conn. 06902, U.S.A. temp. 2400% shielding Beckman Instruments OmbH, 1217' Graphite furnace 100 Programmable; d.1. 4 X 10-12 g d.1. 10-1' g Water-cooled: inert-gas 8 Munich 45, dry, ash, atomize, (100 p l ) (100 pl) shrelding. Safety feature Frankfurter Ring 115, West Germany temp. 3100°C purge gas, gas stop. burn off. Max. for failure of water or Fits Beckman and Pye-Unicam instruments Instrumentation Laboratory Inc.. 455 113 Hartwell Avenue, Lexington, Mass. 02173, U.S.A. Ins Stockport, SK3 OX€, England ~ Graphite and 100 Programmable; S. 3 - 4 x g S. 10- g Fits all AA spectrometers, tungsten furnace six stages, d.1. 0 . 9 ~ 10-12 g d.1. 10- 1 1 g water-cooled, safety inter- ramp or step Max.temp. 3500°C Jock system, automatic cell door, automatic cleaning pressurisation. Solid sampling, tempera- ture. Control led heating via tungsten sensor. True temperature readout Jarrel-Ash Div., Fisher, MTA-2 Tantalum strip 50 Programmable: d.1. 2 x lCQ g N.S. Fits most AA spectro- Scientific Go., dry, ash, atomize. ( 5 0 ~ 1 ) meters.Inert-gas and 590 Lincoln Street, Max. temp. 2400°C hydrogen shielding Waltharn, Mass. 02154, U.S.A. FLA 10 Graphite furnace 50 Programmablei d.f. 2 x 10-11 g N.S. Fits most AA spectro- b dry, ash, atomtre. (5 pl) meters. lnertqas shielding 2 Max. temp. 2800°C but an air ash possible i? S. 8. J. Juniper & Co., 110 Graphite furnace 50 Programmable: S. 3 x 10-11 g N.S. Water-cooled: inertgas O' 7 Potter Street dry, ash, atomize, (10 pl) shielding. All programme ' Harlow, Emex, burn out.Max. stages cover full England temp. 3500°C temperature range Spectronic Services, 9 E & J Brereton, 5' 2 h 4 White Rose Way, Garforth, Leeds LS25 2EF England 50 Programmable: d.f. 10-1' g N.S. Water-cooled; inertgas $ Optica S.A.S., CAT 6 Tantalum strip 20139 Milan, 0 Via Gargano 21, dry, ash, atomize (50 &I] shielding 8 ltaty 3Boden see Perkin-Elmer & Co.GmbH, Postfach 1120, 7770 Uberlingen, West Germany HQA 14 Graphite furnace 100 Programmable: h i s s AA spectrometers. Water-cooled; inert-gas atomize. Max. temp. 2700°C shielding. Permits ramp ashing, gas stop opera- tion. Closed system. Safety feature for failure of water or purge gas d.1. 2 X 10-12 g d.1. 6 x l b i l g Fits Perkin-Elmer and (1 00 p l ) dry. ash (21, (100 A4 Perkin-Elmer Corp., HGA 2100 Graphite furnace 100 Programmable; d.1. 2 X 10-12 g d.1. 5 X 1O-ii g Water-cooled, inert-gas Nor wa! k , dry, ash, atomize. (100 pl) (100 &I) shielding. Gas-stop and Conn. 06856 Max. temp. 2800°C reduced gas flow opera- U .S .A. Ramp accessory tion, and direct temp. for failure of water or purge gas provides linear-type calibration. Safety feature ramp temperature increase in all 3 cycles plus auto high temperature at end of programme Pye Unicam Ltd., York Street, Cambrldae CB1 2PX. England - SP9-01' Graphite furnace 50 Programmable: S. 4.4 x lo-" g N.S. Water-cooled, inert-gas dry, ash, atomize, tube clean, tube blank, with cancel and delay stages. Max. temp. 3000°C shielding. Safety feature for failure of water. Tube life indicator and remote recorder control for 1, 2, 3 or all phases Rank Hilger, H 1 975/ Graphite furnace 100 Programmable: S. 5 x 10-11 g N.S. Wa!er-cooled, inert-gas Westwood Industrial Esiate, FA256 dry, ash, wait, shielding. Background Ramsgate Road, atomize. Max. correction when Wed to Margate, Kent, CT9 4JL, temp. 2600°C H 1550 Atomspek England Shandon Southern A3470 Graphite rod 25 Programmable: d.1. 5 x 10-12 g d.1. 6 x 10-11 g Fits selected AA spectro- Instruments Ltd., dry, ash (21, (5 PI1 (5 PI) meters. Airzooled; inert- Frimley Road, atomize. Max. gas shielding. Pyrolytic Camberley, Surrey, GU16 5ET, temp. 3000°C graphite coating for rods England available in situ. Flame- less accessory can be left In instrument during flame measurements Shimadzu-Seisakusho Ltd., GFA-2' Graphite furnace 50 Programmable: d.1. 5 x 10-12 g Current stablised to 1 Nishinokyo-Kuwabaracho, current stabilised obtain highly reproducible Nakagyo-ku, Kyoto 604, dry, ash, atomize. results. Graphite tube Japan Max. temp. 300O4C replacement is very Varian Techtron Pty. Ltd., CRA 90' Graphite furnace 25 Programmable; 4 x 10-12 g 8 x 10-11 g Fits most AA spectro- 679 Springvale Road, (graphite tube), dry, ash, atomize. (25 P I ) (25 pl) meters. Water-cooled: Mulgrove, Vic. 3171, Threaded Max. temp. 3000°C inert-gas shielding and Australia graphite furnace, hydrogen flame option. easily carried out graphite cup Automatic ramp-hold aiom izaiion. Pyrolytic graphi!e coating on cups and tubes ~~ *New equipment since publication of volume 4

ISSN:0306-1353    

DOI:10.1039/AA9750500027

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

46 Analytical Atomic Spectroscopy 7 Ancillary Topics 7.1 THEORETICAL STUDIES The question of the detection limit and its interpretation continues to stimulate publicat- ions. Alkemade (882) has drawn attention to the assumption that the background fluctu- ations of the paired sample and blank readings arc statistically uncorrelated; in fact, correlation may arisc due to low-frequency noise components in the background emission or in the measuring instrument.The effect on these components i s minimised by reducing the time interval between the measurement of the sample and the blank, and by repeating the measurement several times. This paper is a theoretical treatment of the well-established practical approach of “sample flow modulation” used in emission and absorption flame photometry.The origin and effects of noise in flame AAS have been examined in two papers (755, 883). They confirm that at low absorbances, lamp and flame noise are domin- ant, while at high absorbances, atomization noise dominates. Omenetto, Winefordner and Alkemade (1458) have derived an expression for the effect of self-absorption on fluorescence and thermal emission intensities which takes into account stimulated emission.This theoretical treatment considers the simple idealised case of a two-level atomic system in a flame homogeneous with respect to temperature and compos- ition, and uniformly illuminated by an external quasi-continuum source. Non-dispersive flame AFS has been considered in two papers (90, 842). It is concluded that such systems generally do not show any improvement in signal to noise ratio or detection limits in comparison with dispersive systems, except where optimum energy throughput lies beyond the range of adjustment of the dispersive system, or when the background signal is rclat- ively small, In practical analysis, the problem of background scatter i s best overcome by the use of an auxiliary line source to provide a signal due only to scatter, This signal can then be used to correct the measured signal. 7.2 STANDARD REFERENCE MATERIALS Tables D, E, F and G contain updated information on suppliers of spectrographic stand- ards, spectrographic graphite electrodes, standard metal solutions and reagents for AAS and organo-metallic compounds. Miller ( S p a Speaker, 1975, 20 (2) 1) has comprehensively reviewed the preparation and characterisation of high-purity inorganics and notes that as the “term ‘high-purity’ remains very relative, it i s far better to have more information than required that not enough”.A modification of the statistical method of Dean and Dickson for the testing for normal distributions and for cancelling the out-liers from the set, has been described (1 304) and applied to the estimation of the homogeneity of spectrometric standard samples, The problem of the stability of organometallic compounds used as standards in spectrochemical analysis has been examined (1301).It was found that the acetylacetone complexes and the metallic salts of dithiocarbamic acids are acceptable but accuracy can be maintained only if the standard solutions are freshly prepared from solid compounds just before the analysis.Pinta has reportcd (1 267) on inter-laboratory compar- ison analysis of plant leaves. The elements measured included: N, P, K, Ca, Mg, Fey Cu, Mn, Zn, S, C1 and Na. For determination of trace impurities in metals by electrothermal AAS, new solid standards have been prepared by ion implantation and dissolution in molten urea (184). The standards were Ti in A1 foil and Ti2SO, in urea. 7.3 DOCUMENTATION For workers in the field of AAS, Perkin-Elmer continue to publish their valuable list of references (8,549). Two new journals have appeared during 1975 which promise to make useful contributions to the field of analytical atomic spcctroscopy. First i s the specialistPart I: Fundamentals and Instrumentation 47 jouriial “ICP Information Newsletter” which i s devoted to inductively-coupled plasma- optical analytical spectroscopy.Thc “Newsletter” contains articles on all aspects of the subject, including techniques, instrumentation and abstracts. The second journal is “Euro- pean Spectroscopy News” of which Volume 1, No. 1 was published by Heyden in July 1975.The “News”, appears bimonthly, incorporates the “British Bulletin of Spectroscopy,” and presents news items from all European Spectroscopy Groups on both atomic and molecular spectroscopy. Articles of scientific interest, both reviews and instrument news contribute to the interest and value of this new publications. Table D. SPECTROGRAPHIC STANDARDS (scc following page)48 Analytical Atomic Spectroscopy Aluminium Company of i‘merica, Alcoa Center, Pennsylvania 15069, USA Apex Smelting Co., 6700 Gran: Avenue, Cleveland, Ohio 44105, USA BNF Metals Technology Centre, Grove Laboratories, Denchworth Road, Wantage, Berks OX12 9BJ, England Bundesanstalt fur Materialprufung (BAM), 1 Berlin 45, Unter den Eichen 87, Germ any Bureau of Analysed Samples Lid., Middlesbrough.Cleveland TS8 9EA, England Alcoa Laboratories, X X X X X x x x X x x Newham Hall, Newby, x x x x X X CKD Research Institute, 190 02 Praha, Czechoslovakia Na Harfe 7, x x x Cornit6 de liaison des Industries de metaux non-ferradx de la Communaute Europbenne, Boulevard de Berlaimont, 1000 Brussels, Belgium X G. L. Willan Ltd., Catcliffe, Rotherham, South Yorkshire, England Sheffield Works, x x x X Johnson Matthey Chemicals Ltd., 74 Hatton Garden, ‘Spectromei’ powders ‘Spec pu re’ metals London EClP lAE, England x x x x x x x x x x x x x x Moore Boundy Hamill Ltd.Station House, Potters Bar, Herts EN6 lAL, England X X X X M X x x Office of Standard Reference Materials, National Bureau of Standards, Washington DC 20234, USA Various other metals including high-purity metals Pechiney, 23 Rue Balzac, X Paris 8e, France Spex Industries Inc., PO Box 798, Metuchen, NJ 08840, USA x x X X X X (Glen Creston, The Red House, 37 The Broadway, Stsnmore, Midd lesex.England ) X Zinc 8. Alliages, 34 Rue Collange. 92307 Lavallois-Perret, France1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Table E. SPECTROGRAPHIC GRAPHITE ELECTRODES Baird-Atomic, Inc, 125 Middlesex Turnpike, Bedford, Mass 0 1730, USA Carbon Products Division, Union Carbide Corp, 270 Park Avenue, New York, NY 10017, USA (ARL Ltd, Wingate Road, Luton, Beds, England) Gencral Graphites Inc, First and Monroe Street, Bay City, Mich 48706, USA Johnson-Matthey Chemicals Ltd, 74 Hatton Garden, London EC1 P 1 AE, England Lc Carbone (GB) Ltd, Portslade, Sussex, England Le Carbonc Lorraine, 45 Rue des Acacias, 75821, Paris, France Met-Bay Inc, 900 Harrison Street, Bay City, Mich 48706, USA Poco Graphite, Inc, PO Box 2121, Decatur, Texas 76234, USA Ringsdoe-Werke GmbH, 53 Bonn-Bad Godesberg, West Gemany (Mining & Chem- ical Products Ltd, Alperton, Wembley, Middlesex HA0 4PE, England) Spex Industries, Inc, 3880 Park Avenue, Metuchen, NJ 08840, USA (Glen Creston, The Red House, 37 The Broadway, Stanmore, Middlesex, England Ultra Carbon Corp, PO Box 747, Bay City, Mich 48706, USA (Heyden & Son Ltd, Spectrum House, Alderton Crescent, London NW4, England) Part I : Fundamentals and Instrumentation 49 Table F.STANDARD METAL SOLUTTONS (MS) AND REAGENTS FOR AAS(R) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 1 7. 18. Aldrich Chemical Co., Inc, 940 W. St. Paul Avenue, Milwaukee, Wis. 53233, USA (R) J. T. Baker Chemical Co., 222 Red School Lane, Phillipsburg, N.J. 08865, USA (MS, R) Barnes Engineering Co., 30 Commerce Road, Stamford, Conn. 06902, USA (MS) B.D.H. Chemicals Ltd., Poole, Dorset BH12 4NN, England (MS, R) Bio-Rad Laboratories, 32nd and Griffin Avenues, Richmond, Calif. 94804, USA (MS) Carlo Erba, Divisione Chimica Tndustriale, Via C.Imbonati 24, 20159 Milano, Italy Eastman Organic Chemicals, Eastman Kodak Co., 343 State Street, Rochester, NY 14650, USA (R) Fisons Scientific Apparatus Ltd., Bishop Meadow Road, Loughborough, Leics. LEll ORG, England (MS, R) Harleco, Div. of American Hospital Supply Corp., 60th and Woodland Avenues, Philadelphia, Pa. 19143, USA (MS) Hopkin & Williams Ltd., PO Box 1, Romford, Essex RMl IHA, England (MS, R) V. A. Howe & Co. Ltd., 88 Peterborough Road, London SW6, England (MS) Instrumentation Laboratory Inc., 1 13 Hartwell Avcnuc, Lexington, Mass. 02173, USA (MS) Johnson Matthey Chemicals Ltd., 74 Hatton Garden, London EClP IAE, England (R) Kwh-Light Laboratories Ltd., Colnbrook, Bucks., England (R) (Anderman & Co.Ltd., Battlebudge House, 87-95 Tooley Street, London SE1, England) May & Baker Ltd., Dagenham, Essex RMlO 7XS, England (R) E. Merck, D 61 Darmstadt, West Germany (R) Spex Industries Inc., 3880 Park Avenue, Metuchen, N.J. 08480, USA (MS) Ventron Corp., Alfa Products, 44 Congress Street, Beverly, Mass. 01915, USA (MS) (MS)50 Analytical Atomic Spectroscopy 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. Table G. ORGANOMETALLIC STANDARDS Angstrom Inc., P.O. Box 248, Belleville, Mich. 481 11, USA Baird-Atomic Inc., 125 Middlesex Turnpike, Bedford, Mass. 01 730, USA J. T. Baker Chemical Co., 222 Red School Lane, Phillipsburg, N.J. 08865, USA B.D.H. Chemicals Ltd., Poole, Dorset BH12 4": England Messrs Burt and Harvey Ltd., Brettenham House, Lancaster Place, Strand, London WC2, England Carlo Erba, Divisione Ch3mica Industriale, Via V.Imbonati 24, 20159 Milano, Italy Conostan Div., Continental Oil Co., P.O. Drawer 1267, Ponca City, Okla. 74601, USA Durham Raw Materials Ltd., 1-4 Great Tower Street, London EC3R 5AB, England Eastman Organic Chemicals, East man Kodak Co., 343 State Street, Rochester, N.Y. 14650, USA Hopkin and Williams Ltd., P.O. Box 1, Romford, Essex RMl lHA, England E. Mcrck, D 61 Darmstadt, West Germany Moore Boundy Hamill Ltd., Station Housc, Potters Bar, Herts. EN6 lAL, England National Spectrographic Laboratories Inc., 19500 South Miles Road, Cleveland, Ohio 44128, USA Office of Standard Reference Materials, National Bureau of Standards, Washington, D.C. 20234, USA Research Organic /Inorganic Chemical Corp., 1 1686 Sheldon Street, Sun Valley, Calif. 91352, USA Ventron Corp., Alfa Products, 44 Congress Street, Beverly, Mass. 01915, USA

ISSN:0306-1353    

DOI:10.1039/AA9750500046

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

PART II METHODOLOGYlntroductlon In part 11, the term Methodology covers all aspects of the application of the techniques and instrumentation of AAS, AES and AFS to chemical analysis. The format adopted for previous volumes has been retained, with the subject matter treated under the two principal headings of (1) General Information, covering new methods, inter-la boratory comparisons and referee methods, and (2) Applications, where specific methods of analysis are reviewed and tabulated. The classification of the range of applications into nine main fields of analysis also follows the established pattern. Some duplication of entries may be found in instances where a method i s relevant to more than one section. 53

ISSN:0306-1353    

DOI:10.1039/AA9750500051

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

EXPLANATION OF TIIE TABLES Each of the Applications sections, 2.1 to 2.9, is accompanied by a table which summarises the principal analytical features of the references from which the corresponding section is compiled. All relevant references are included in the appropriate table, while the accomp- anying text discusses only the more noteworthy contributions. These Applications Tables form a convenient source of information for analysts interested in particular elements, matrices, sample treatments or atomization systems.In many cases, sufficient detail i s given for the analytical procedure to be followed; absence of such detail usually means that the information was not directly available to the compiler of the table and the original reference should be consulted.The key to the tables is given below. ELEMENT MATRIX CONCENTRATION TECH. ANALYTE The elements determined are listed in alphabetical order of chemical symbol, except that, for space economy, multi-element applications ( 5 elements or more) are given at the end of some tables. The wavelength, in nanometres, at which Q e analysis was performed. An indication, necessarily brief, of the material analysed.The concentration range or level of the element in the original matrix, expressed as 70 or pgg-1 for solids and mgl-1 or pg ml-1 for liquids. The atomic spectroscopy technique i s indicated by A (absorp- tion), E (emission) or F (fluorescence). The form of the sample, as presented to the instrument, is indicated by S (solid), L (liquid) or G (gas or vapour). ‘d.1.’ = detection limit in the analyte. SAMPLE TREATMENT A brief indication is given of the sample pre-treatment required to produce the analyte. ATOM I WTION REF. The atomization process is indicated by the abbreviations A (arc), S (spark), F (flame) or P (plasma), usually with some additional descriptive detail. The number refers to the main Reference Section, which gives the title of the paper and the name(ss) of the author(s), With address. 53

ISSN:0306-1353    

DOI:10.1039/AA9750500053

出版商:RSC    

年代:1975

数据来源: RSC