摘要:

ANALYST, FEBRUARY 1992, VOL. 117 203 Complexometric Determination of Copper in Isolation, Alloys and Complexes Using DL-Cysteine as a Selective Masking Agent B. Narayana Department of Studies in Chemistry, Mangalore University, Mangalagangothri 574 199, India M. R. Gajendragad Kuvempu University, 6. R. Project, Shimoga 577 20 1, India An accurate, selective and rapid complexotitrimetric method is described for the determination of Cull in the presence of other metal ions. The method is based on the selective complexing ability of cysteine with Cull. Copper in the aliquot is initially complexed by the addition of ethylenediaminetetraacetic acid (H4edta) solution and the excess H4edta is titrated against Pb(NO& solution (pH 5.0-6.0) using hexamine and Xylenol Orange. A known excess of DL-cysteine in water is then added to release the H4edta from the CuI1-H4edta complex.This is subsequently titrated against Pb(NO& to the same sharp end-point. The amount of H4edta released from the complex is thus equivalent to the amount of Cull in the solution. The method works well for Cu in various alloys and metal complexes. Reproducible and accurate results are obtained in the concentration range 3-32 mg per aliquot with a relative error of ~0.6% and a standard deviation of <0.04%. The effect of various cations and anions is also studied. The interference of a number of ions, such as ZP, Sntv, TI11t, Hg" and Pd" can be overcome by the use of suitable secondary masking agents. Keywords: Copper; complexometric titration; cysteine masking agent; alloy analysis; complex analysis Complexometric methods for the determination of Cu have superseded the classical iodometric method because they are less prone to interference from ions commonly encountered in the analysis of various materials containing Cu.In these methods, the sample is dissolved in a suitable medium, the Cu" is complexed with ethylenediaminetetraacetic acid (H4edta) and the complex is decomposed by reducing Cu" to Cu' and stabilized as a CU' species. The H4edta subsequently released from the complex is determined titrimetrically. Many methods have been reported in the literature for the determi- nation of Cu based on the technique of masking. Thus binary or ternary reagent mixtures, such as ascorbic acid and thiocyanate ,1,2 ascorbic acid and thiourea,3 thiourea, ascorbic acid and thiosemicarbazide4 (or a small amount of 1 , l O - phenanthroline or 2,2'-bipyridyl) or a single reagent serving as a reductant and a complexing agent, such as thiosulfate,5 thiourea,6 thioglycolic acid ,7 mercaptopropionic acid7 and mercaptosuccinic acid8 have been used for decomposing the Cu1'-H4edta complex.The applicability of such a method for the analysis of numerous alloys and ores is also studied and reported.2.7.8 Thiols are known to react with Cu" to form a strong CU' complex as follows: CU" + 3RSH + Cu'(SR) + R-S-S-R + 3H+ In this paper, the results of a study on the feasibility of using DL-cysteine, which can form a strong complex with Cull, is reported. The reagent is found to be a better chelating agent than those reported earlier.Experimental Reagents Copper(1l) standard solution. Prepared by dissolving CuS04.5H20 of analytical-reagent grade in distilled water and standardized by the thiocyanate method.9 Ethylenediaminetetraacetic acid solution, = 0.02 mol dm-3. Prepared by dissolving the disodium salt of H,edta in distilled water. Lead nitrate solution, 0.02 mol dm-3. Prepared by dissol- ving Pb(N03)2 in distilled water and standardized by the chromate method.9 m-Cysteine, 0.5% solution in water. Xylenol orange, 0.5% solution in water. Procedure To a solution containing 3-32 mg of Cu, 0.02 mol dm-3 H,edta solution is added in excess. The solution is diluted to about 100 ml and the pH is adjusted to 5.0-6.0 with hexamine. The excess of H4edta is titrated with 0.02 mol dm-3 Pb(N03)2 solution using Xylenol Orange as indicator.DL-Cysteine solution in water is then added in excess (molar ratio of copper to cysteine of 1 : 3). The change of colour from green to yellow is observed during the addition of the cysteine solution. The solution is left to stand for about 5 min with intermittent shaking. The H4edta released is then titrated against the Pb(N03)2 solution to the same end-point as before. The results of seven determinations of Cu" are presented in Table 1. Interference Study A number of metal ions, rare-earth metal ions and anions are studied for their possible interference in the determination of Cu by this method. Cations such as Zr'", Snrv, T l I ' I , Pd" and Hg" are found to interfere rather severely, but the interfer- ences can be obviated by using suitable secondary masking agents such as fluoride (10% NH4F, 5-10 ml) for ZrIV (28 mg) and Sn'" (10 mg), hydrazine sulfate (2% solution, 2-5 ml) for Tlrrl (10 mg) and thiocyanate (5% NH4SCN, 5-10 ml) for Pd" (5 mg) and Hg" (25 mg).The results are given in Table 2. Analysis of Alloys Samples (1 .O-1.5 g) of copper-based alloys were dissolved in concentrated HN03 and the oxides of nitrogen expelled with the use of concentrated H2S04 until the brown fumes ceased Table 1 Determination of copper in copper sulfate solution, n = 5 Copper Copper Standard Recovery 3.19 3.21 0.02 100.63 6.37 6.36 0.02 99.84 12.74 12.70 0.03 99.67 15.93 15.92 0.02 99.94 19.11 19.19 0.02 100.49 25.48 25.43 0.02 99.80 31.85 31.93 0.04 100.25 takedmg foundmg deviatiodmg (Yo.)204 ANALYST, FEBRUARY 1992, VOL.117 Table 2 Determination of copper in the presence of foreign metal ions and anions, n = 3. Copper present in the solution = 6.37 mg Ion Zn" CO" Ni" Cd" Mn" Fe"' Ce"' Crlll A P Ru"' Rh"I Au"' La111 V'" TiiV UV1 Pd" Hg" T p l ZrIv SnlV Chloride Fluoride Acetate Citrate Tartrate Phosphate Amount in Amount of solutiodmg Cu foundmg 10 50 6 30 6 30 16 32 2.5 5 6 12 14 28 5 10 5.5 27.5 4 8 4 8 4 8 14 28 5 25 5 25 12 24 1 5 5 25 2 10 14 28 5 10 50 100 50 100 50 100 50 100 50 100 50 100 6.38 6.39 6.36 6.38 6.37 6.36 6.37 6.38 6.39 6.37 6.39 6.37 6.37 6.41 6.35 6.36 6.36 6.38 6.41 6.88 6.42 6.39 6.39 6.39 6.38 6.39 6.38 6.36 6.34 6.35 6.34 6.38 6.38 6.39 6.35 6.36 6.41 6.38 6.37 6.38 6.39 6.37 6.37 6.41 6.37 6.39 6.39 6.37 6.34 6.35 6.38 6.39 6.39 6.41 Meadmg 6.39 6.37 6.37 6.38 6.38 6.38 6.39 6.36 6.37 6.40 6.41 6.39 6.39 6.37 6.35 6.36 6.39 6.36 6.40 6.38 6.38 6.39 6.38 6.38 6.35 6.39 6.40 Recovery (Yo) 100.31 100.00 100.00 100.16 100.16 100.16 100.31 99.84 100.00 100.47 100.62 100.31 100.31 100.00 99.68 99.84 100.31 99.84 100.47 100.16 100.16 100.31 100.16 100.16 99.68 100.31 100.47 to evolve.The residue was extracted with distilled water and made up to 250 ml in a standard flask. Aliquots (5 ml) were used for titration as per the recommended procedure. For comparison, the Cu content in the alloys was also determined by thiocyanate. The results of the analysis are presented in Table 3. Analysis of Copper Complexes Samples (0.1-0.2 g) of the complex were decomposed using aqua regia (hydrochloric-nitric acid, 3 + 1) and heated to near dryness and the residue was dissolved in water and made up to 100 ml in a standard flask.Aliquots of 10 ml were used for the determination of Cu by the proposed procedure. The results are presented in Table 4. Table 3 Analysis of copper alloys Copper found by cornplexo- metric titration" Alloy (Yo 1 Cu-Ni 71.22 Bronze 80.90 Brass 67.69 Aluminium-bronze 77.28 Gun-metal 85.10 Standard deviation 0.03 0.04 0.02 0.03 0.04 (% * Average of four determinations. t Average of three determinations. Copper found by thio- cyanate- gravimetric met hod t 71.28 80.79 67.64 77.19 84.96 (%.) Standard deviation 0.06 0.04 0.05 0.04 0.05 (Yo Table 4 Analysis of copper complexes Copper found Copper present 18.20 18.34 28.82 28.94 23.04 22.99 33.13 33.00 21.36 21.29 (Yo) (Yo) * Copper complex of thiocarbohydrazide.t Copper complex of 4-amino-5-mercapto-3-propyl-1,2,4-triazole. $ Copper complex of 4-amino-5-mercapto-3-(p-methoxyphenyl)- 7 Copper complex of 4-amino-5-mercapto-3-methyl-l,2,4-triazole. $ Copper complex of 3-(o-tolyloxymethyl)-4-amino-5-mercapto- 1,2,4-triazole. 1,2,4-triazole. Results and Discussion The quantitative displacement of H4edta from the Cu-H4edta complex by cysteine indicates that the Cu-cysteine complex is more stable than the Cu-H4edta complex at room tempera- ture and that H4edta is released instantaneously. For the complete release of H,edta, a slight excess of DL-cysteine above the molar ratio of 1 : 3 is necessary. A larger excess of the reagent does not have any adverse effect on the results of the determination of Cu.It is found that L-cysteine forms a 1 + 1 complex with Cu,"J but during complexation Cu" is reduced to Cu'. Merits of the Method The merit of the reagent is that it does not form any precipitate with either Cu", the metal ion to be estimated, or Pb", the titrant, in the concentration range of Cu studied under the experimental conditions described. This facilitates a sharp end-point. The method works well especially at low concen- trations of Cu" in the range 3-32 mg per aliquot with a relative error of <0.6% and a standard deviation of <0.04%. The main advantage of the proposed method is that heating or cooling is not required before or during the titration. The method does not involve extraction of the Cu-H4edta complex and hence is simple and can be carried out rapidly in a single step. The H4edta solution does not require standardization and no pH re-adjustment is required for the final titration. References 1 Kores, E., and Remport, H., Chemist-Analyst, 1957, 56, 91. 2 Rao, B. V., Athavale, S. V., Rao, Y. V., Acharyalu, S. L. N., and Tamhankar, B. V., Indian J . Technol., 1971, 9, 157.ANALYST, FEBRUARY 1992. VOL. 117 20s 3 4 5 6 Raoot, K. N., Raoot, S . . Rao. B. V., and Lahari. D. P., Indiun J . Teclinol., 1976. 14. 254. Singh, R. P . . Tulunru, 1972, 19, 1421. Cheng. K. L.. And. Chrm., 1958, 30, 243. Pribil. R . , and Vesely, V., Tulanra, 1961, 8, 743. 9 Vogel. A. 1 . . A Text Book of Quantitative Inorgunic Analysis Including Elementary Instrumental Analvsis. Longmans, Lon- don. 4th edn.. 1978. pp. 444462. Pierre. L.. and Clande. H . J . , Bull. Soc. Chirn. Fr., 1079, 457. 10 7 X Kaoot. S . . Raoot. K: N.. and Rukmani Desikan. N.. Indiun J . Technol., 1983, 21. 39. Rukmani Desikan. N.. and Vijayakumar. M., Anulyst, 1985. 110. 1399. Puper 1I026H1 J Received June 5, 1991 Accepted July 25, I991

ISSN:0003-2654    

DOI:10.1039/AN9921700203

出版商:RSC    

年代:1992

数据来源: RSC

摘要:

ANALYST, FEBRUARY 1992, VOL. 117 207 Analysis of Mixtures of Dialkyldithiophosphate, Bis(dialkoxythiophosphinoy1) Disulfide and Elemental Sulfur Leszek Margielewski and Stanistaw Plaza* Department of Chemical Engineering and Environmental Protection, University of Lodz, Pomorska 18, 91-416 Lodz, Poland The method presented for the determination of zinc dialkyldithiophosphate, bis(dialkoxythiophosphinoy1) disulfide and elemental sulfur in the presence of each other is based on thiomercurimetric titrations. Zinc dialkyldithiophosphate is determined by titration with p-dimethylaminophenylmercury(ll) acetate with Michler's thioketone as indicator. The sulfur and bis(dialkoxythiophosphinoy1) disulfide are determined after their reduction. Bis(dialkoxythiophosphinoy1) disulfide is reduced by using tributylphosphine and titration as for zinc dialkyldithiophosphate. The sulfur is treated with bis(2-methoxyethoxy) dihydride and titrated with o-hydroxymercuribenzoic acid in the presence of dithiofluorescein as indicator.The method is simple, rapid, reproducible and accurate and samples do not require separation or other preliminary stages prior to their analysis. The method is suitable for monitoring changes in thiophosphorus lubricating oil additives during engine runs. Keywords: Zinc dithiophosphate; bis(dialkoxythiophosphinoy1) disulfide and elemental sulfur determination; thiomercurimetric titration; lubricating oil additives Zinc dialkyldithiophosphate (ZDTP) is added to lubricating oils to serve as an antioxidant. In addition, owing to the formation of protective films on metal surfaces, it prevents the corrosive attack of oxidation products, and also exhibits useful load-carrying properties. Sodium and potassium dialkyldithiophosphates are used extensively as flotation collectors for sulfide minerals.These salts of dialkyldithiophosphoric acid have also been found to be an important class of analytical reagents for the separation and determination of metal ions. It is generally accepted that ZDTPs act as both chain- breaking antioxidants (radical scavengers) and preventative antioxidants (hydroperoxide decomposers). Hydroperoxide is decomposed in an oxidation reaction with ZDTP' according to the equation 4[(R0)2PSSI2Zn + R'OOH -+ [(R0)2PSS]6Zn40 + [(R0)2PSS]2 + R'OH (1) In a further reaction, the basic ZDTP [(R0)2PSS]6Zn@ is oxidized mainly to bis(dialkoxythiophosphinoy1) disulfide, [(RO)2PSS]2 (DS).2 Elemental sulfur is formed in the reaction between DS and hydroperoxide with thionic sulfur elimina- tion .3 Bis(dia1 koxyphosphinoyl) disulfide is unstable and hydrolyses to dialkyl- and dialkylthiophosphoric acids and sulfur according to the reaction (R0)2PSSP(OR)2 + H20+ (R0)ZPSH + (RO);?POH + S I t (2) 0 tI 0 II It 0 0 It has been shown that the reaction products of ZDTPs formed during oxidation,'" pyrolysis7 and engine runs* include DS and basic ZDTPs as major products, with smaller amounts of the compounds (R0)2PSSR, (RS)3PS, (RS),PO, (RS)3P, (RO)*P(O)SR and elemental sulfur.3 These thio- phosphorus species were detected by 31P nuclear magnetic resonance (NMR) spectrometry.The antiwear and antioxida- tive behaviour of mixtures of these compounds may be different depending on the amounts of these thiophosphorus species. Hence, a knowledge of the changes in thiophosphorus species in working lubricants is necessary. A procedure for the analysis of mixtures containing ZDTP, DS and elemental sulfur has not hitherto been reported; ZDTP and DS have been detected and satisfactorily deter- *To whom correspondence should be addressed. mined in mixtures using 31P NMR spectrometry.1,2,4-* Although the development of 31P NMR has opened the way for interesting investigations of lubrication mechanisms with the use of ZDTP, practical difficulties in dealing with very complicated mixtures that also contain elemental sulfur may appear formidable. In spite of an extensive literature on the determination on ZDTP, cited by Hutchings et ~ 1 .~ 9 no one method can be recommended for analysis in the presence of DS and sulfur. Zinc dialkyldithiophosphate in the presence of DS may be determined by a titrimetric method using dimethylaminophenylmercury(II) acetate with Michler's thioketone as an indicator.10 Bis(dialkoxythiophosphinoy1) disulfide in the presence of ZDTP has been determined by a spectrophotometric method.11 In this method, ZDTP interferes with the determi- nation of DS; in the recommended procedure, ZDTP was separated with an ion-exchange resin, which complicates the analysis. Sulfur dissolved in hydrocarbon solution may be reduced with sodium aluminium bis(2-methoxyethoxy) dihy- dride to sulfide and determined by titration with o-hydroxy- mercuribenzoic acid.12 This paper reports a method for analysing mixtures of ZDTP, DS and elemental sulfur. For the determination of ZDTP and sulfur, the most suitable are thiomercurimetric methods as mentioned above ,10,12 whereas for the determina- tion of DS, an analytical investigation of the reduction of DS to the dialkyldithiophosphate anion, which can be determined by titration with p-dimethylaminophenylmercury(r1) acetate, was undertaken. Experimental Reagents and Solutions All chemicals and solvents were of analytical-reagent grade, except for p-dimethylaminophenylmercury(II) acetate (APM) , zinc diisobutyldithiophosphate and bis(diisobuty1- oxythiophosphinoyl) disulfide, which were synthesized in this laboratory.Zinc diisobutyldithiophosphate was prepared from butan-2-01, phosphorus pentasulfide, sodium hydroxide and zinc sulfate. 13 Bis( 0,O-diisobutyloxythiophosphinoyl) disulfide was obtained by oxidizing sodium dithiophosphate with iodine. 14 The thiophosphorus compounds prepared were characterized by elemental analysis, and infrared (IR), 1H and 31P NMR spectrometry. Pure APM was synthesized by the procedure developed by Pesci.15316208 ANALYST, FEBRUARY 1992, VOL. 117 Lubricating oils and lubricating oil additives were of technical grade. A 0.01 rnol dm-3 APM solution was prepared by dissolving 3.797 g of the reagent in 10 ml of dimethylformamide, adding 2 mi of acetic acid and diluting to 1 dm' with absolute ethanol. This solution was further diluted with absolute ethanol to obtain the required concentrations.The solution can be used directly as a working standard without standardization. A stock solution of APM is stable for at least 3 months if stored in a dark bottle. A 0.01% m/v indicator solution of Michler's thioketone (MT) was freshly prepared in absolute ethanol. Solutions of APM and MT are most stable in anhydrous solvents. A 0.05 rnol dm-3 solution of o-hydroxymercuribenzoic anhydride (HMB) (POCh, Gliwice, Poland) was prepared by dissolving 16 g of the reagent in a mixture of 20 g of diethanolamine and 50 ml of water and then in 200 ml of ethanol and, after standing for 3-4 h, filtering. This solution was standardized with diphenylthiourea.*7 A 2 x 10-4 rnol dm-3 solution was prepared by dilution with ethanol- water (9 + 1) containing 1% of diethanolamine.The stock solution was kept in a refrigerator. A 0.01% m/v indicator solution of dithiofluorescein (POCh) was freshly prepared by dissolving 2 mg of indicator in 1 ml of a solution of 20 g of ethylenediaminetetraacetic acid (EDTA) (disodium salt) and 20 g of triethylamine in 1 dm3 of water and then diluting to 25 ml with water. A 5 x 10-2 rnol dm-3 solution of tributylphosphine in toluene and a 0.01% m/v solution of sulfur in toluene were prepared. White oil solutions of ZDTP (0.65% m/m), DS (0.65% m/m) and sulfur (0.01% m/m) and lubricating oil additives (the concentrations are given in Table 4) were prepared by dissolving these compounds in a technical-grade oil. Titration Procedures Determination of DS and ZDTP in the presence of each other The procedures were calibrated by titration of various amounts of DS and ZDTP as follows.To 0.1-2.0 g of oil sample containing more than 50 pg of each compound, which was diluted with chloroform or toluene to a total volume of 5 ml, a few drops of MT were added. The mixture was then titrated with APM, the end-point being indicated by the visual change of the solution from yellow to blue-violet. To the same solution 1 ml of tributylphosphine was added and the colour of the solution returned to yellow after 1 min. A 1 ml volume of sulfur solution was added and the solution was then titrated with APM to a blue-violet colour. When greater amounts of oil were present in the solution, the mixture became non-homogeneous during titration owing to the formation of an alcoholic solution of the reagent.Further toluene or chloroform was added to obtain a clear solution. In a toluene solution of oils (containing ZDTP and DS to be analysed), the end-point was less sharp than in chloroform. In the first titration APM was consumed by ZDTP and in the second by 0, 0'-diisobutyl hydrogen phosphorodithioate formed in the reduction of DS. In titration with 5 X 10-3-2 X 10-4 rnol dm-3 reagents, a blank comparison solution of MT must be used, the titration being continued until the colours of both solutions match. The amount of reagent in the blank titration must be subtracted from the amounts of reagent when analysing the ZDTP and DS results. Determination of elemental sulfur in the presence of ZDTP and DS To another 0.1-2.0 g of oil sample containing ZDTP and DS and sulfur (BO.5 pg), which was diluted with anhydrous, sulfur-free toluene to a total volume of 5 ml, a few drops of sodium aluminium bis(2-methoxyethoxy) dihydride (SAMD) were added, mixed and then 2 ml of ethanol-1 rnol dm-3 NaOH (1 + 1 v/v) were added.Before the titration, ethanol was added to give a homogeneous solution and a few drops of dithiofluorescein were added. The solution was titrated with 2 X 10-4 rnol dm-3 HMB to the disappearance of the blue colour of the indicator. In the titrations with 2 x 10-4 rnol dm-3 HMB the value of the blank titration of the indicator is subtracted from the amount of reagent when analysing the results. Theory In samples containing ZDTP and DS, the ZDTP reacts with APM as follows: + Zn(OOCCH3)2 One mole of ZDTP consumes 2 rnol of APM; DS is reduced with tributylphosphine according to the reaction + (C4Hgl3P=0 The unreacted tributylphosphine reacts with sulfur: (C4H9)3P + S + (C4H9)3P=S ( 5 ) In the second titration 1 rnol of DS reacts with 2 rnol of APM.In the second sample elemental sulfur is reduced with SAMD according to NaAIH2(0CH2CH20CH3)2 + S + NaAIS(OCH2CH20CH3)2 + H2 (6) and then the product of reduction is decomposed with water: NaOH NaAIS(OCH2CH20CH3)2 -NaOH + AI(OH)3 + Na2S HZ0 + 2CH30CH2CH20H (7) Sulfide is determined by titration with HMB: Hg- S-Hg The reagent SAMD also reduces DS but not quantitatively, and ZDTP and (C4H90)2DSS- do not interfere in the determination of Sz-. Results and Discussion For the analysis of ZDTP-DS-sulfur mixtures, the determina- tion of DS was the main problem studied.The studies included the choice of reductant, complete recovery and the effects of ZDTP, sulfur and lubricating oil additives on the determina- tion of DS. Of the numerous methods for the reduction of disulfides, the most suitable for the determination of DS in the presence of ZDTP and sulfur is reduction with tributylphos- phine. The procedure found to be most suitable is that detailed under Experimental. Table 1 gives the results of the determination of DS. The recovery was nearly 100%. The reproducibility of the determination of DS was good, with a relative standard deviation (RSD) of 2.07% when nine samples with a mean content of 1.255 mg were analysed.The method can be recommended for general use.ANALYST. FEBRUARY 1992. VOL. 117 209 The results for the determination of ZDTP and DS in the presence of sulfur are presented in Table 2. The results were in good agreement with the amounts taken for analysis and the average recoveries of ZDTP and DS were near 100%. Further, these results show that ZDTP and DS can be determined in the presence of each other, and sulfur had no effect on the recovery of either compound. Thiophosphorus compounds, potentially formed in lubri- cating oils during engine operation, also do not interfere in the Table 1 Determination of bis(U, O-diisobutylthiophosphinoyl) disul- fide Sample Taken/ Recovery No. mg Found/mg (Yo) 1 0.315 0.324,0.320,0.309,0.314 100.5 2 0.945 0.942,0.972,O.942,0.955 100.8 3 1.260 1.325.1.266, 1.295. 1.325 103.4 4 1.798 1.803,1.803,1.805,1.745 99.6 Table 2 Determination of bis(0, U-diisobutylthiophosphinoyl) disul- fide and zinc diisobutyldithiophosphate in the presence of elemental sulfur (0.01%) Takcn/mg Found/mg Recovery (YO ) No. ZDTP DS ZDTP DS ZDTP DS Sample 2.79 2.39 2.79 2.39 2.79 4.78 2.79 4.78 5.58 2.39 5.58 2.39 5.58 4.78 5.58 4.78 2.80 2.37 2.77 2.41 2.79 4.80 2.73 4.88 5.76 2.35 5.64 2.22 5.42 4.83 5.57 4.91 100.6 99.7 100.0 97.8 103.2 101.1 97.1 99.4 99.2 100.8 100.4 102.1 98.3 98.9 101.1 102.7 Average 99.8 100.4 Table 3 Determination of bis(diisobutylthiophosphinoy1) disulfide and zinc diisobutyldithiophosphate in the presence of (RO)?PSSR and elemental sulfur (S 0.01%) Taken/mg Foundlmg Recovery (%) No.ZDTP DS ZDTP DS ZDTP DS Sample 1 5.58 4.78 5.44 4.86 97.5 101.7 2 5.58 4.78 5.46 4.86 97.8 101.7 3 5.58 4.78 5.46 4.98 97.8 104.2 4 5.58 4.78 5.50 4.90 98.6 102.5 Average 97.9 102.5 determination of ZDTP and DS. For example, Table 3 gives the results for the determination of ZDTP and DS in the presence of sulfur and (RO)?PSSR. Good reproducibility of the determination of DS was confirmed, with an RSD o f 1.15% (n = 4). The apparent increase in the recovery of DS is connected with lower recoveries of ZDTP. A possible interference from other lubricating oil additives in the determination of DS was also studied. Other additives commonly present in fully formulated lubricating oils wcrc added to the DS solution to determine the effect of each on the Table 5 Determination of bis( 0,O-diisobutylthiophosphinoyl) disul- fide and zinc diisobutyldithiophosphatc in a fully formulated mineral oil Take n/m g Found/mg Recovery (%, ) No.ZDTP DS ZDTP DS ZDTP DS 1 2.745 1.179 2.74 1.18 99.8 100. I 2 2.745 1.179 2.74 1.23 99.8 104.3 3 2.745 1.179 2.69 1 . I9 97.9 101 .o 4 2.745 1.179 2.71 1.21 98 .9 102.7 5 2.745 1.179 2.74 1.23 99.8 104.3 Sample Average 99.2 102.5 Table 6 Determination of elemental sulfur in the prcycnce of zinc diisobutyldithiophosphate, bis(O,O-diisobutylthiophosphinoyl) di- sulfide and (RO)?PSSR Rc 1 at i vc Average standard Sample Taken/ rccovcry deviation No. mg Found/mg (Yo) ) 1 12.96 12.39, 12.14, 13.87, 100.0 4.6 2 265.6 263.7.267.9,255.3, 97.5 1.7 12.14, 13.39 251.1.257.0 Table 7 Results of the determination of zinc diisohutyldithiophos- phate, bis( 0,O-diisobutylthiophosphinoyl) disulfidc and sulfur in mineral oil after four-ball wear test.Load, 30 kg; time. 30 min; temperature of oil, 80°C ConcentratiodlO-3 mol dm- ~ ZDTP DS Su I fur Betore tc\t After test Atter tc\t Atter tc\t 23.68 17.82 3.96 1.20 Table 4 Effect of other lubricating oil additives on the determination of bis(0,O-diisobutylthiophosphinoyl) disulfide Concen- DS Lubricating tration taken/ DS found/mg Recovery (Yo ) oil additive (% m/m) mg Pol yisobuten y 1 succinimide Octadecylamine 2.6-Di-rer-r-butyl- 4-methylphenol Poly(mcthy1 met hacry late) Basic barium sulfonate (TBN-20) 3.0 1.31 0.655 0.262 1 .0 1.476 0.737 0.295 0.5 I .476 0.947 0.295 3.0 1 ,300 0.655 0.262 3.0 1.256 I .004 0.502 1.26 0.664 0.273 I .490 0.735 0.294 1.520 0.941 0.320 1 ,300 0.660 0.249 1.210 1.020 0.498 1.26 0.657 0.242 1.471 0.73s 0.296 1.490 0.965 0.320 1.290 0.661 0.261 1.220 0.996 0.503 1.26 0.652 0.273 1.359 0.740 0.290 1.541 0.953 0.297 1.290 0.653 0.266 1.230 1 .008 0.498 1.26 0.659 0.262 1.443 0.74 1 0.293 I .530 0.954 0.291 1.307 0.65 1 0.260 1.241 1.006 0. 50 1 96.2 100.4 100.2 99.3 100. 1 99.4 103.0 100.7 104.1 100. 1 100.2 98.9 97.6 I 00.3 99.6210 ANALYST, FEBRUARY 1992, VOL. 117 recovery of DS. The other lubricating oil additive concentra- tions were selected for study arbitrarily, but these concentra- tions may be used in practice. The results for the determina- tion of DS are given in Table 4. Only in the presence of tert-butylphenol were the recoveries of DS increased by approximately 3%.No apparent interference from any of the other lubricating oil additives tested was observed in the determination of DS. Table 5 gives the results of the determination of ZDTP and DS in the presence of sulfur and the composition of lubricating oil additives in mineral oil. The concentrations of lubricating oil additives were as follows: succinimide 2% , viscosity improver 6%, calcium sulfonate 3% and 2,6-di-tert-butyl-4- methylphenol 1%. Generally, the results of the recovery of DS are 2.5% high, and all the results for ZDTP are low. The end-point was located visually and because the analysed oil was coloured it was probably responsible for these errors. Elemental sulfur can be determined in the presence of DS, ZDTP and the other organic thiophosphorus compounds tested by the procedure described under Experimental.Table 6 gives the results of the determination of sulfur. The recoveries and precision of the method were generally good. The results for the determination of sulfur were also not influenced by the other lubricating oil additives. An application of the proposed method is illustrated in Table 7, which shows the results of a four-ball machine wear test for 30 min with mineral oil containing ZDTP and carbon black; the concentrations of ZDTP, DS and sulfur in the oil were also determined. The recommended method is generally satisfactory for the determination of more than 1 x 10-7 mol dm-3 of ZDTP and DS and more than 0.5 pg of elemental sulfur in the presence of each other.Hence concentrations of ZDTP and DS as low as 0.01% in 1 ml or 1 g samples of used lubricating oil solutions can be determined with good reproducibility. Some used oils were so dark that the visual location of the end-point was not possible, and the determination of ZDTP and DS was therefore carried out by two-phase titration, in which the end-point was indicated by the visual change in the ethanol layer from yellow to blue-violet. In the determination of ZDTP, DS and sulfur, metal dithiocarbamates interfere, as dithiocarbamates react with APM and o-hydroxymercuri- benzoic acid. Conclusions The proposed procedure for the analysis of mixtures of ZDTP, DS and elemental sulfur is rapid, simple, reproducible and accurate, and samples do not require preliminary separation or another intermediate stage prior to their analysis.In view of the results obtained and the simplicity of the procedure, the method can be recommended for the determination of mixture composites in working lubricating oils. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 References Paddy, J. L., Brook, P. S., and Waters, D. N., J. Chem. SOC., Perkin Trans. 2 , 1989, 1703. Rossi, E., and Imparato, J., Chim. Znd. (Milan), 1971,53,838. Sanin, P. J., Blagovidov, J. F., Vipper, A. B., Kuliev, A. M., Krein, S. E., Ramaya, K. S., Shor, G. J., Sher, V. V., and Zaslavsky, Y. S., New Concepts of the Mechanism of Action and Depletion of Motor Oil Additives, 8th World Petrol. Cong., Proc., 5, 91, Applied Science Publishers, London, 1971. Burn, A. J., Tetrahedron, 1966, 22, 2153. Brunton, G., Gilbert, B. C., and Mawby, R. J., J. Chem. SOC., Perkin Trans. 2, 1976, 650. Paddy, J. L., Lee, N. C., and Waters, D. N., Tribol. Trans., 1990,33, 15. Watkins, R. C., Tribol. Znt., 1982, 15, 13. Marshall, G. J., Appl. Spectrosc., 1984, 38, 522. Hutchings, M. J., Moody, G. J., and Thomas, J. D. R., Analyst, 1987, 112,601. Plaza, S., Analyst, 1984, 109, 1313. Plaza, S., Microchem. J., 1982, 27, 544. Wronski, M., Talanta, 1974, 21, 776. Brazier, A. D., and Elliott, J. S., J. Znst. Pet., 1967, 53, 63. Hu, P.-F., and Cheng, W.-Y., Hua Hsueh Hsueh Pao, 1956,22, 215; Chem. Abstr., 1958, 52, 7186c. Pesci, E., Gazz. Chim. Ital., 1899, 23, 521. Pesci, E., Chem. Zentralbl., 1901, 1, 452. Wronski, M., Talanta, 1977, 24, 347. Paper 1/04156H Received August 9, 1991 Accepted October 1 I, 1991

ISSN:0003-2654    

DOI:10.1039/AN9921700207

出版商:RSC    

年代:1992

数据来源: RSC

摘要:

ANALYST, FEBRUARY 1992, VOL. 117 21 1 Spectrophotometric Determination of Quaternary Ammonium Salts by a Flow Injection Method Coupled With Thermochromism of Ion Associates Tadao Sakai Department of Chemistry, Asahi University, 1851 Hozumi, Hozumi-cho, Gifu 50 1-02, Japan A selective and rapid spectrophotometric method has been established for the determination of cetylpyridinium and benzalkonium chlorides by a flow injection technique coupled with ion-pair extraction and thermochromism of the ion associates. Selectivity can be enhanced because the absorbance of ion association compounds formed between co-existing amines and the anionic tetrabromophenolphthalein ethyl ester disappears at elevated temperatures in the flow cell. Accordingly, interferences due to amine associates can be eliminated by absorbance measurement at 45°C.The sample throughputs were 60 h-1 for cetylpyridinium and 50 h-1 for benzalkonium. The calibration graphs were linear in the range 5 x 10-7-2 x 10-6 rnol dm-3 for both compounds. The relative standard deviations ( n = 5) for 1 x 10-6 rnol dm-3 cetylpyridinium and benzalkonium at 45 "C were both 2.1 %. The proposed method was used for the selective and rapid determination of quaternary ammonium compounds in pharmaceuticals. Keywords : Ce t ylp yridin ium and benzalkon ium chloride determination; ion -pair extraction with tetra b rom op h enolp h thalein eth yl ester; flow injection; the rmo-spectrop hotom etry Although Bromophenol Blue (BPB)1 and Bromocresol Green2 have been commonly used as ion-association reagents for quaternary ammonium salts, these dyes are diprotic acids which show a narrow optimum pH range for extraction and poor extractability of the ion associates into organic solvents.In addition, linearity of the calibration graphs in the lower concentration ranges is poor. Therefore, monoprotic acidic dyes such as Orange II,3 sodium picrate,4 4-(2,6-dibromo-4- hydroxyphenylimino)cyclohexa-2,5-dienone~ and tetrabro- mophenolphthalein ethyl ester (TBPE),6 which have a wider optimum pH range compared with diprotic acid dyes were investigated as ion-association reagents for trace amounts of quaternary ammonium salts. Of these reagents, TBPE has the advantages of larger molar absorptivity (1 x 105 1 mol-* cm-I), superior extractability and good reproducibil- ity.However, TBPE is not suitable for the selective determi- nation of quaternary ammonium compounds and amines by the convenient method7 at pH 8-9. When the pH is increased, interferences from amines decrease but are not eliminated completely. Benzethonium has been determined by a solvent extrac- tion-flow injection (FI) method using the coloured BPB- quinine associate.8 Although this method has good selectivity, the manifold is complicated and sample throughput low. It has been observed that the absorbance of ion-association compounds formed be tween TBPE and amines approaches zero at 6O"C.g It follows that thermochromism of amine associates might be used to eliminate the interference of amines in the determination of quaternary ammonium salts. This paper describes an FI system with solvent extraction and a temperature-controlled micro-scale flow cell for the selective, sensitive and rapid determination of cetylpyridinium and benzalkonium. Experimental Reagents All reagents were of analytical-reagent grade and were used without further purification.Stock standard cetylpyridinium solution, 1 X 10-3 rnol dm-3. Prepared by dissolving 0.0358 g of cetylpyridinium chloride (Kishida Chemical , Tokyo) in distilled water and diluting to 100 ml. Other standards were prepared by appropriate dilution of the stock solution. Stock standard benzalkonium solution, 1 X 10-3 mol dm-3. Prepared by dissolving 0.0354 g of benzalkonium chloride (Nakalai Tesque, Kyoto) in distilled water and diluting to 100 ml. Other standards were prepared by appropriate dilutions. Amine solution, 5 x 10-3 mol dm-3.Prepared by dissolving appropriate amounts of amine hydrochloride or hydromaleate in distilled water. Buffer solution, p H 3-13.0. Prepared by mixing equal volumes of 0.3 rnol dm-3 potassium dihydrogen phosphate and 0.1 mol dm-3 sodium borate. The pH was adjusted with 1 mol dm-3 sodium hydroxide or 0.5 mol dm-3 sulfuric acid. rnol dm-3. Prepared by adding 0.1 mol dm-3 hydrochloric acid to 25 ml of aqueous 4 X 10-4 mol dm-3 TBPE potassium solution (TBPEsK) until the colour changed from blue to yellow. The solution was then equilibrated with 100 ml of 172-dichloroethane. Working solutions were prepared by appropriate dilutions. TBPE solution in dichloroethane (TBPE-H), 1 X Apparatus A Hitachi Model 556 double-beam spectrophotometer and a Hitachi Model 057 x-y recorder were used with 10 mm cells for absorption measurements.Extractions were carried out with an Iwaki Model KM shaker. A Hitachi-Horiba pH meter with a combined glass electrode was used. Procedure for the Batchwise Method Place an aliquot (0.5-5 mi) of 1 x 10-5 mol dm-3 cetylpyridinium or benzalkonium solution and 1 ml of buffer solution (pH 12.8) into a 100 ml separating funnel and dilute the mixture with distilled water to 10 ml. Shake the solution mechanically with 5 ml of 1 x 10-5 mol dm-3 TBPE-H solution for 5 min. Transfer the organic phase into a test-tube fitted with a stopper and centrifuge to remove water droplets. Measure the absorbance at 610 nm against a reagent blank as a reference at 25 or 45 "C.Procedure for the FI Method A schematic diagram of the flow system used is shown in Fig. 1. The absorbance was measured at 610 nm using a Soma Optics Model S-3250 double-beam spectrophotometer (data212 n ANALYST, FEBRUARY 1992. VOL. 117 P Q , I I D PS W (aq) W (org) Fig. 1 Schematic diagram of the flow system for the determination of quaternary ammonium salts. BS, buffer solution (pH 12.5); RS, reagent solution ( 5 x mol dm-3 TBPE-H in dichloroethane); P, pump (flow rate, 0.8 ml min-I); S, sample injector (sample volume 140 PI); R , reaction tubing (0.5 mm i.d. x 2 m); PS, phase separator; FC, thermo-controlled micro-scale flow cell; D. spectrophotometric detector; T, thermo-controller; Rec, recorder; NV, needle valve; and W. waste TI ,luminiu - block mm im 55 m m y 8 mm Fig.2 cell Cut-away diagram of the thermo-controlled micro-scale flow output, 0-10 mV) with a 10 mm flow cell (S PI). The flow cell was a laboratory-made thermo-controlled cell as displayed in Fig. 2. A constant temperature within the range 20-80 "C was maintained by a compact thermocontroller (Shimaden, Tokyo). Signals were recorded using a Toa Electronics FBR-25 1A recorder. A double-plunger micropump (Sanuki Kogyo, DM2U-1026) was used to propel the carrier solution and the reagent solution. The samples (140 pl) were injected into the carrier stream by a six-way injection valve (dead volume, 80 pl) to which a 60 p1 loop was attached. The membrane of the phase separator was made of porous poly(tetrafluoroethy1ene) (PTFE). Flow lines were of PTFE tubing (0.5 mm i.d.).Results and Discussion Effect of pH on Batchwise Extraction of Ion-association Complexes With TBPE-H The effect of pH on the extraction of cetylpyridinium, procaine, diphenhydramine, chlorpheniramine and methyl- ephedrine was examined in the pH range 3.4-12.8 with 1 X 10-5 rnol dm-3 TBPE-H in dichloroethane solution. The results are shown in Fig. 3. Absorbance of the blue TBPE- cetylpyridinium associate, which has A,,,, at 610 nm, was maximum and constant in the pH range 8.0-12.8. On the other hand, absorbance of the red association complexes formed between TBPE-H and the amines mentioned above was maximum in the pH range 8-10, with the absorbance decreasing markedly at higher pH values. Furthermore, the absorbances of ion association complexes formed with all the amines examined except chlorpheniramine were close to that of the reagent blank.Consequently, interferences due to these amines could be eliminated. 0 C (D $ 0.4 - 2 0.2 - 0 i 1 I 3 5 7 9 11 13 PH Fig. 3 Effect of pH on batchwise extraction of TBPE associates: 1. 2.5 x 10-6 rnol dm-3 cetylpyridinium; 2. 2.5 x 1OVi rnol dm-' chlorpheniramine; 3,2.5 x rnol dm-3 diphenhydramine; 4,2.5 x mol dm-' methylcphedrine; and 6, reagent blank. TBPE.H. 1 x lo-' mol dm-'; wavelength, 610 nm; and reference, water mol dm-3 procaine; 5 , 2.5 x 0.4 1 al C m -9 2 0.2 - Q 0 I ____- ------_ -__-- 500 550 600 Wavelengthlnm 650 Fig. 4 Effect of temperature on the absorption spectrum of TBPE.H-butylamine associate: A , 20°C; and B , 45 "C. Butylamine, 2 x 10-5 rnol dm-3; TBPE.H, 3.2 x rnol dm-3; pH, 8; and reference, water Thermochromism of Amine Association Complexes With TBPE-H In a previous paper," it was reported that TBPE-H-amine association complexes exhibit changes in absorbance with temperature (thermochromism).As can be seen in Fig. 4, absorbance by the TBPE.H-butylamine associate (A,,,,, 565 nm) approaches zero when the temperature is increased from 20 to 45 "C. Accordingly, a temperature of 45 "C was chosen to eliminate interferences from amines in the determination of cetylpyridinium and benzalkonium salts. It is assumed that TBPE-H reacts with amines to form ion-association com- pounds that dissociate at elevated temperatures as shown below for butylamine. TBPE- + +H.NH?C4H9 TBPE.H.NH2C4HY (blue, (red-violet , A,,,, 610 nm, A, 565 nm) PH 8) heat TBPE.H.NH2CJH9 Z T B P E - H + NHZCJHQ cool (yellow, A,,,, 410 nm) The chemical bond between the proton and butylamine is not strong, hence, increasing the temperature might cause the ion-association compound to dissociate to the free acid and amine.At temperatures over 45 "C, the red colour due to the ion-association compound is seen to disappear completely. Effect of pH in the FI method The extraction of cetylpyridinium was examined in the pH range 3-12.5 with 5 x 10-6 rnol dm-3 TBPE-H in dichloro- ethane solution. The peak height remained constant at aANALYST, FEBRUARY 1992, VOL. 117 213 maximum over the range pH 7-12.5. This range was much wider than that observed for acetylcholine under similar conditions. 1 0 Effect of TBPE.H Concentration Effect of the TBPE.H concentration on the formation of ion association complexes was investigated.The concentration of TBPE-H was varied from 1 x 10-6 to 2 x 10-5 mol dm-3. Although a maximum peak height was obtained at concentra- tions >5 x 10-6 mol dm-3 for 1 x 10-6 mol dm-3 cetylpyridinium, at higher TBPE-H concentrations the toler- able concentration of co-existing amines was lower and the baseline was noisier. In this work therefore, 5 X 10-6 mol dm-3 TBPE-H solution in dichloroethane was used. Comparison of Phase Separators Two kinds of phase separator were compared and the designs are shown in Fig. 5. Type A, designed by Motomizu and Oshima,11 has a sloped groove (membrane chamber depth, 2 mm; membrane chamber width, 2 mm) with a porous PTFE membrane (0.8 pm pore size).Type B, designed by the authors, has a body made of poly(chlorotrifluoroethy1ene) and a microporous PTFE tube (i.d., 1 mm; thickness 0.5 mm; porosity 60%; length 2.5 cm). With both separators, the organic phase was recovered sufficiently. However, with type B, the peaks were broader and the retention time was longer. For efficient phase separation, type A was used in this work. Other Variables In order to examine the efficiency of extraction, the length of the extracting coil was varied from 1 to 4 m. Although the maximum peak height was obtained when the tubing was 3 m in length, 2 m of tubing was chosen. With this length, sample throughput was greater and peak height was only 8% less than that with 3 m of tubing.The effect of the sample injection volume over the range 100-180 pl was investigated; a 140 p1 Organic f phase / Segment Type A Organic phase t 1 Aqueous phase ---c Aqueous phase ----------- Segment - C' - Type B Fig. 5 Phase separators tested. A, PTFE membrane filter (pore size 0.8 prn); B, microporous PTFE tube (1 rnm i.d., thickness 0.5 mm, porosity 60%, length 2.5 cm); and C, connector made of Daiflon volume was chosen. Of the extracting solvents, 172-dichloro- ethane, dichloromethane and l73-dich1orobenzene, the first was found to be the best for colour stability and reproducibil- ity of extraction. Flow rates of 0.8 ml min-1 were chosen for the reagent and carrier solutions. Calibration Graphs At 25 and 45 "C, good linear relationships were found over the range 5 x 10-7-2 x 10-6 mol dm-3 of cetylpyridinium when 140 p1 of the standard solutions were injected.The relative standard deviations ( n = 5 ) were 2.0% for 1 X 10-6 mol dm-3 cetylpyridinium at 25°C and 2.1% at 45°C. The limit of detection [signal-to-noise (S/N) = 31 was 6.1 X 10-8 mot dm-3 at 25 "C and 6.3 x 10-8 mol dm-3 at 45 "C. The peak height at 45 "C was about 10% less than that at 25 "C. Similar results were obtained for benzalkonium. The relative standard deviations (n = 8) were 1.8% for 1 X 10-6 mol dm-3 at 25 "C and 2.1%, at 45 "C. The limit of detection (S/N = 3) was 6.3 x 10-8 rnol dm-3 at 45°C. The sample throughputs were 60 h-1 for cetylpyridinium and 50 h-1 for benzalkonium. Table 1 Effect of some amines on cetylpyridinium determination at different temperatures by an FI method: cetylpyridinium concentra- tion, 1 X 10-6 rnol dm-3; TBPE.H in dichloroethane solution.5 x 10-6 mol dm-3; pH, 12.5; and wavelength, 610 nm Compound Procaine Diphenhydramine Chlorpheniramine Ephedrine Methylephedrine Eserine Butylamine Trimeth ylamine Triethylamine Triethanolamine [ Amine J : [cetylpyridinum] 20 30 30 1 2 5 40 80 30 40 10 10 20 1 2 10 Recovery (%) 25 "C 100 108 100 100 118 142 102 121 100 103 110 101 106 100 120 99 45 "C 98 - - - 100 98 100 100 100 98 102 - - - - - A' B' C' D' '10 mini Ti m e/m i n Fig. 6 Flow injection signals of TBPE-cetylpyridiniurn and a mixture with amine associates at (a) 2.5 and ( 6 ) 45°C: A and A', 1 x rnol dm-3 cetylpyridinium; B and B', 3 x mol dm-' procaine with cetylpyridinium; C and C' , 2 x 10-6 rnol dm-3 chlorpheniramine with cetylpyridinium; and D and D', 5 x 10-6 rnol dm-3 chlorphenir- amine with cetylpyridinium.TBPE.H, 5 x rnol dm-3; pH, 12.5214 ANALYST, FEBRUARY 1992, VOL. 117 ~~ Table 2 Determination of cetylpyridinium and benzalkonium in commercial samples by the FI method, n = 3 25 "C 45 "C Nominal/ Found/ Recovery Found/ Recovery Sample mg mg (% 1 mg (% 1 1* 1 .oo 1.25 f 0.02 124 0.97 * 0.03 97.3 21- 4.00 4.37 f 0.13 109 3.97 f 0.12 99.2 3$ 1.00 1.46 k 0.02 145 0.98 f 0.02 97.9 49 0.1 0.101 f 0.01 101 - * Main content: cetylpyridinium chloride; chlorpheniramine maleate (2 mg); naphazorine hydrochloride (1 mg); and iproheptine hydro- 'r Main content: cetylpyridinium chloride; and dextromethorphan (90 mg).$ Main content: cetylpyridinium chloride; chlorpheniramine maleate ( 5 mg); and procaine hydrochloride ( 5 mg). 9 Main content: benzalkonium chloride. - chloride (3 mg). Interferences Various other amines (Table 1) were added to cetylpyridinium and their interferences on the determination were studied. Inorganic compounds including sodium chloride, calcium chloride and sodium acetate had previously been found not to interfere.7.9 Aliphatic and aromatic amines (triethylamine, triethanolamine, butylamine, chlorpheniramine and pro- caine) gave positive errors at 25 "C but their interferences were eliminated by absorbance measurement at 45 "C. Flow injection signals for standard cetylpyridinium and for mixtures with procaine or chlorpheniramine solutions at 25 and 45 "C are shown in Fig.6. Application Practical use of the method was assessed by applying it to the determination of cetylpyridinium and benzalkonium in phar- maceutical preparations. Sample solutions were prepared after filtration and suitable dilution. Table 2 shows the results obtained at 25 and 45 "C with the FT system. Although strong interferences from co-existing amines were observed at 25 "C, the interferences could be satisfactorily eliminated in the determination of cetylpyridium at 45 "C. In conclusion, the FI method coupled with solvent extrac- tion and thermochromism of ion associates, described in this paper, has the advantages of sensitivity, selectivity and rapidity for quaternary ammonium salt determinations. This research was partially supported by a Grant-in-Aid for General Scientific Research, No. 3640503, from the Ministry of Education, Science and Culture (Japan). References 1 2 3 4 5 6 7 8 9 10 11 Auerbach, E., Ind. Eng. Chern. Anal. Ed., 1943, 15, 492. Irving, H. M. N. H . , and Markham, J. J . , Anal. Chim. Acta, 1967, 39, 7. Scott, G. V., Anal. Chern., 1968,40, 768. Sakai, T., Bunseki Kagaku, 1978, 27,444. Tsurubo, S., Ohno, N., and Sakai, T., Nippon Kagaku Kaishi, 1980, 6,828. Sakai, T., Bunseki Kagaku, 1975.21, 199. Sakai, T., Hara, I . , and Tsubouchi, M., Chern. Pharrn. Bull., 1976,24, 1254. Miyaji, T., Hibi, K., and Sakai, T., Bunseki Kagaku, 1990, 39, 73. Sakai, T., and Ohno, N., Analyst, 1981, 106, 584. Sakai, T., Gao, Y., Ohno, N., and Ura, N., Chern. Lett., 1991, 163. Motomizu, S., and Oshima, M., Analyst, 1987, 112, 295. Paper 1104044H Received August 5, 1991 Accepted October 7, 1991

ISSN:0003-2654    

DOI:10.1039/AN9921700211

出版商:RSC    

年代:1992

数据来源: RSC

摘要:

ANALYST, FEBRUARY 1992, VOL. 117 R R 215 I *D Rec M Micellar Systems in Flow Injection : Determination of Gadolinium With 1=(2=Pyridylazo)-2=naphthol in the Presence of Triton X-100 Jose Luis Perez Pavon and Bernard0 Moreno Cordero" Department of Analytical Chemistry, Nutrition and Food Sciences, University of Salamanca, Salamanca, Spain The optimum conditions for the determination of Gd using the Gd-l-(2-pyridylazo)-2-naphthol (PAN) system in micelles of Triton X-100 have been studied. Under the conditions chosen, the molar absorptivity was 4.8 x 104 dm3 mol-1 cm-1. It is possible to determine Gd at levels of between 0.9 and 8.8 pg ml-1 by injection into a stream, buffered at pH 9.2, containing 1.2 x 10-3 mol dm-3 PAN (Triton X-100 : PAN = 0.15 g : 1.0 mg). The influence of the presence of electrolytes in the matrix on peak height was studied. The interferences produced by heavy metals were eliminated by extracting their diethyldithiocarbamates into CHC13-EtOAc (1 + 1).Keywords: Gadolinium determination; micellar media in flow injection; I-(2-p yridylazo)-2-naphthoI; Triton X- 700; rare earths Various analytical techniques have been used for the determi- nation of rare earths at trace levels such as neutron activation, isotope dilution, mass spectrometry, and X-ray methods. However, most of these techniques require specialized and expensive instruments. The increasing importance of these elements in high technology components and many other fieldsl-3 has required the development of simple and rapid analytical methods for their determination. Flow injection (FI) is an excellent technique for such purposes owing to its simplicity, versatility and low cost.However, there are few reports on the use of FI for the determination of rare earths.4-6 1-(2-Pyridylazo)-2-naphthol (PAN) has been employed both for spectrophotometric determination7 and for the extraction and separation of rare earths.8-10 However, both the chromophore and the chelates formed are insoluble in water, necessitating the use of aqueous alcoholic media or other less polar solvents The high solubilization capacity of micellar systems has permitted the modification or the development of analytical procedures in which the extraction process can be avoided and, in many instances, the sensitivity and selectivity of the procedure can be enhanced.12J3 The great analytical potential inherent in the use of organized molecular systems in general, and micellar systems in particular, together with the advantages of these systems, has found application in virtually all analytical techniques, both in the determination of trace elements14 and in separa- tion.15 However, there are very few reports concerning the use of these methods in F1.435 In the present work, the spectrophotometric behaviour of the Gd-PAN system in the presence of Triton X-100 was studied.A method is proposed for the determination of trace amounts of Gd using an FI technique. Experimental Reagents A standard solution of Gd was prepared by dissolving the appropriate amount of the oxide (99.9%, Sigma) in 1 ml of concentrated HCl and diluting with water.Solutions of PAN were prepared by dissolving appropriate amounts of the product (Merck) in aqueous solutions of Triton X-100. Apparatus A Varian Techtron Model 635 spectrophotometer with a Radiometer Rec 61 recorder and 1 cm optical pathlength * To whom correspondence should be addressed. cuvettes was used. The pH measurements were performed with a Radiometer PHM 51 pH meter. The manifold (Fig. 1) was constructed by using Teflon tubing (0.5 mm i.d.) and a Gilson Minipuls (4 channels) peristaltic pump. The sample injector was a Rheodyne 2050 valve with interchangeable loops of different capacities. The absorbance was measured with a Coleman 55 spectropho- tometer with a Hellma 178 12-QS flow cuvette with a pathlength of 1 cm and an internal volume of 18 p1.All statistical parameters were obtained with the 'Statworks' program for an Apple Macintosh computer. Procedure In the spectrophotometric determination, the solution of PAN in Triton X-100 (Triton X-100 : PAN = 0.15 g : 1.0 mg) and variable amounts of Gd were added to 5.0 ml of a buffer solution (pH = 9.2), bringing the volume up to 50 ml with distilled water. The absorbance was measured at 560 nm against a blank, after 30 min. In the determinations using FI, 123 pl of Gd solution at pH 2.2 (HCl) were injected in the presence of 0.4 mol dm-3 NaN03 into a stream of 1.2 x 10-3 mol dm-3 PAN (Triton X-100:PAN = 0.15 g: 1.0 mg), buffered at pH 9.2 (0.005 rnol dm-3 HB02-B02-) and the FI responses were recorded at 560 nm. Results and Discussion Spectrophotometric Study of the Gd-PAN-Triton X-100 System In a buffered medium (HB02-B02-, pH = 9.2) and in the presence of Triton X-100 the Gd-PAN system exhibits two absorption maxima at 535 and 560 nm, respectively (Fig.2). P n I U Fig. 1 Schematic diagram of the manifold used for the determination of Gd: R, reagent [1.2 X 10-3 rnol dm-3 PAN; Triton X-100: PAN, 0.15 g : 1.0 m ; pH = 9.2 (HB02-B02-) ; P, peristaltic ump (qtotal = 4.4 ml min-17; I, injection valve (123 pl]; D, detector = 560 nm); M, mixing coil (20 cm); and Rec, recorder216 ANALYST, FEBRUARY 1992, VOL. 117 0.30 0.10 I I 525 575 Un m Fig. 2 Absorption spectra of the Gd-PAN system: 8.0 x 10-6 mol dm-3 Gd; and 8.0 X 10-5 rnol dm-3 PAN. 1, Triton X-100 : PAN = 0.15 g : 1.0 mg; and 2 and 3, extracts in diethyl ether (recorded after 5 and 30 min) 0, 0.40 C e v) 9 a 0.20 1 2 3 4 5 5 10 15 20 Time/min Fig.3 Variations in absorbance with time and the ratio of Triton X-100: PAN for Triton X-100 : PAN ratios (g : mg) of 1,0.15; 2,0.25; 3, 0.50; 4, 1.00; and 5, 1.50: 8.0 x 106 rnol dm-3 Gd, 8.0 x 10-5 rnol dm-3 PAN and pH = 9.2 (0.02 rnol dm-3 HB02-B02-) The spectrum obtained is similar to that obtained without using Triton X-100 but extracting with diethyl ether, the most suitable medium according to Shibatag for determination; this extract is, however, not stable. The time required to reach the maximum response does not depend on the concentration of Triton X-100, but rather on the Triton X-100 : PAN ratio; the signal decreases as this ratio increases (Fig.3) owing to a decrease in the concentration of the chromophore in the micelles as their number increases. Similar effects have been described by other workers. 16 The variation in the absorbance with pH produces a bell-shaped curve (Fig. 4), which exhibits a plateau for pH values between 8 and 10; the working pH chosen was 9.2. In the presence of Triton X-100, the slope ratio method indicated a stoichiometry of 1 : 3 (Gd: PAN). This ratio differs from the values reported by other workers.8.17 The system obeys Beer’s law at 560 nm in media buffered at pH 9.2 (0.02 rnol dm-3 HB02-B02-), fitting the equation A = 4.8 X 104 [Gd] + 0.006 ( r = 0.9998). The micellization process causes modifications in the pK values of dissociation and protonation of the chromophore18 as a function of the concentration of the surfactant in solution.However, as the dissociation pK would be shifted towards higher values, under the experimental conditions 7 8 9 10 11 12 PH Fig. 4 Variations in absorbance with pH: 8.0 X 10-6 rnol dm-3 Gd; 8.0 X 10-5 rnol dm-3 PAN; and Triton X-100 : PAN = 0.15 g : 1.0 mg 1.20 1 I 2 6 10 14 PAN/10-4 mot dm-3 1 2 3 4 5 6 BuffedlO-2 mot dm-3 1 2 3 4 5 I I I 1 I q/mt min-1 100 200 300 400 Mcm Fig. 5 Influence of manifold and chemical variables on the peak hei ht. A, PAN; B, buffer; C, q (flow rate); and D, I (length of mixing coifi. Sample, 8.0 X 10-5 Gd; pH, 4.9, carrier, Triton X-100 : PAN = 0.15 g: 1.0 mg; pH, 9.2 (HB02-B02-) and injection volume, 123 pI used in this work, PAN must be present mainly in the undissociated form.Moreover, as the lanthanide must be present in the form of a hydroxy complex, the complexing reaction can be expressed as: [Gd(OH),]’-” + 3PAN H Gd(PAN)3 + 3H20 + (n - 3)OH- Determination of Gd Using FI The influence that the presence of the surfactant might exert on the shape and the parameters defining the FI response was studied by injecting 123 pl of Carmoisine (40 ppm) into a simple single channel manifold [length of mixing coil (I) = 50 cm; flow rate (4) = 2.2 ml min-11 and into a stream of water in which the concentration of Triton X-100 was varied from 0.001 to 5%. No appreciable changes appeared in the FI responses obtained, indicating that the presence of micelles in the system does not affect the response. Optimization of the Analytical Parameters Fig.5 shows the influence of the concentration of PAN, the flow rate, the length of the reactor and the concentration of buffer solution on peak height.ANALYST, FEBRUARY 1992, VOL. 117 1 217 I - 3 Time L - Fig. 7 Variations in peak height 1 and 2, in the presence and 3 and 4, absence of NaN03. 1, pH = 4.9; 2, pH = 2.6; 3, pH = 4.9, 0.4 mol dm-3 NaNO,; and 4, pH = 2.6,0.4 mol dm-3 NaN03 Injection volumes greater than 123 pl produce double peaks, which are unsuitable for analytical purposes. The pH of the sample must be between 2 and 3; lower pH values cause double peaks and higher pH values lead to a drop in the signal, owing to a decrease in the rate of exchange of the OH groups by PAN. In order to verify this, stopped-flow FI responses were obtained, halting the pump before and after the residence time ( t ) for samples at pH 2.6 and 4.9 (Fig.6). If the pump is halted after time t it can be seen, at pH 2.6, that the signal does not increase with the reaction time (complete reaction, high ligand exchange rate), whereas at pH 4.9, an increase in the signal takes place, indicating a slower exchange of ligands. If the pump is stopped before time t , at pH 2.6, the signal is seen to increase faster than at pH 4.9 and reaches constant absorbance in a shorter time. The presence of electrolytes in solution modifies both the shape and size of the micelles,*9.20 mainly because of ionic exchange on their surfaces.21 Further, electrolytes can modify the initial reaction rates, which causes a large matrix effect in some FI determinations.Fig. 7 shows the variations in peak height in the presence and absence of 0.4 mol dm-3 NaN03 at two different pH values; higher concentrations of salt increase the blank signal, hindering calibrations. The other electrolytes studied (KCI, KN03, NaCl and NaC104) produce similar effects. Analytical Characteristics of the Method For the analytical conditions chosen [h = 560 nm, injection volumes = 123 p1, flow rate ( 4 ) = 4.4 ml min-1 and I = 50 cm], 1 2 min I Time - Fig. 8 Calibration peaks for injection of A, 0.9; B, 2.1; C, 3.4; D, 4.6; E, 5.7; F, 6.9; G, 7.8; and H, 8.8 ppm of Gd. Reagent: 1.2 X mol dm-3 PAN; Triton X-lOO:PAN, 0.15 g:1.0 mg; pH, 9.2 (HBOz-B.O,-); qtotal = 4.4 ml min-1; V , = 123 p1; h = 560 nm; and mixing coil, 20 cm the peak absorbance varies linearly with the concentration of Gd between 0.9 and 8.8 pprn (Fig.8), and fits the equation A = 0.06 + 1.6 x 104[Gd] ( r = 0.9999). Measurements of ten solutions containing 1.5 ppm of Gd gave a relative standard deviation of 0.48%. Interferences Of the anions studied, the following do not interfere (error <3%) at an anion: Gd ratio of 100: 1 (Gd = 8.0 x 10-6 mol dm-3): F-, CI-, Br-, I-, NO3-, S032- and CO32+. Oxalate, phosphate and citrate interfere and must be absent. The interference produced by heavy metals (except for CeIV) can be eliminated by extracting their diethyldithiocarbamates with a mixture of CHC13-EtOAc (1 + 1). The interference produced by CeIV can be eliminated by precipitating the basic salt formed with KBr03. All the other lanthanides interfere.1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 References Kolbourn, B. T., J. Less-Common Met., 1985, 111, 1. Yoldjian, B., J. Less-Common Met., 1985, 111, 17. Falconnet, P., J. Less-Common Met., 1985, 111, 9. FIAstar Flow Injection Analysis Bibliography, 1974-1988. Moreno Cordero, B., Perez Pavon, J. L., and Hernandez Mendez, J., Quim. Anal., 1989, 8,231. R8iieka, J., and Hansen, E. H., Anal. Chim. Acta., 1988, 214, 1. Marczenko, Z . , Spectrophotometric Determination of Elements, Ellis Horwood, Chichester, 1976. Shibata, S., Anal. Chim. Acta, 1959, 22, 470. Pustelnik, N., Kuznik, B., and Czakis Sulikowska, D. M., Anal. Chim. Hung., 1985, 118, 93. Czakis Sulikowska, D. M., and Malinowska, A., Anal. Chim. Hung., 1985. 118, 121. Kuznik, B., Inorg. Nucl. Chem., 1981,43, 3363. Hinze, W. L., in Solution Chemistry of Surfactants, ed. Mittal, K. L., Plenum Press, New York, 1979, vol. 1. Pelizzetti, E., and Premauro, E., Anal. Chim. Acta, 1985, 169, 1. Cline Love, L. J., Habarta, J. G., and Dorsey, J. G., Anal. Chem., 1984,56, 133A. Armstrong, D. W., Sep. Purif. Methods, 1985, 14,213. Rosendorfova, J., and Cermakova, L., Talanta, 1980, 27, 705. Navratil, O., Collect. Czech. Chem. Commun., 1960,31,2492. Al'bota, L. A., J. Anal. Chem. USSR (Engl. Transl.), 1985,40, 771. Diaz Garcia, M. E., and Sanz-Medel, A., Talanta, 1986, 33, 255. Chen, J., Su, T., and Mou, Ch. Y . , J. Phys. Chem., 1986, 90, 2418. Callahan, J. H., and Cook, K. D., Anal. Chem., 1982, 54, 59. Paper 1 /03687D Received July 19, 1991 Accepted September 9, 1991

ISSN:0003-2654    

DOI:10.1039/AN9921700215

出版商:RSC    

年代:1992

数据来源: RSC

摘要:

ANALYST, FEBRUARY 1992, VOL. 117 219 BOOK REVIEWS HPLC in Pharmacy and Biochemistry Edited by Magda SarSunova, Oldrich HanC and Bohumil KakaC. Pp. x + 335. Huthig. 1990. Price DM98.00. ISBN 3-7785-1 699-X. This book is aimed at chemists interested in the analysis of drugs or in clinical biochemistry and at students, and is said to be suitable for continuing education of pharmacists and clinical biochemists. It is a translation from the original 1984 Czechoslovakian edition , which has been revised to some extent. Despite its 1990 preface, it contains no references beyond 1987. A short introduction on the development of chromato- graphic methods is followed by a general section, on the principles of chromatographic methods and a comparison of HPLC with other methods, a theoretical section, and a section covering working techniques including instruments, columns, selection of stationary and mobile phases, detection and quantification. These parts form a minor portion of the book and give brief surveys of the topics covered.Much information is summarized in tables, for example eluotropic series of solvents and available column packings. However, the refer- ences are selective and do not appear to date beyond 1981: for example, that for a listing of size-exclusion supports is dated 1980. There is no discussion of microbore HPLC. The major part, comprising more than three-quarters, of the book summarizes the applications of HPLC in phar- maceutical and toxicological analysis (about half) and in biochemistry and clinical analysis (about one quarter).In this part, sub-sections are devoted to statements of methods and results reported for particular classes of drugs or analytes. A main class, such as drugs acting on the central nervous system, is broken down into separate sections covering groups of analeptics, hypnotics and sedatives, antiepileptics, and so on. Many sub-sections cover only one or two pages. Selected chromatograms are reproduced in some sections. A useful feature is the provision of separation data in tabular form which enables the salient characteristics of methods for certain substances to be appreciated rapidly. However, the informa- tion is given in the text in a factual manner only and there is little discussion of the relative merits of different analytical systems to guide the reader. The book concludes with a two-page summary of abbrevia- tions used and an index.It is not clear why the publisher has also included advertisements for other books on chromato- graphy dated no later than 1988. Although well printed, the text suffers from erratic proof- reading. This book is flawed by the lack of recent references in a rapidly developing field, which means that much of the information presented is out of date, and by the lack of critical assessment of the material included. It cannot be recommen- ded as fulfilling the aims claimed for it. D. H . Calam HPLC in Clinical Chemistry By I. N. Papadoyannis. Chromatographic Science Series. Volume 54. Pp. x + 488. Marcel Dekker. 1990. Price $1 15.00 (US and Canada); $1 38.00 (all other countries).ISBN 0-8247-81 39-2. High-performance liquid chromatography (HPLC) is nowa- days widely used in clinical laboratories and there is scope for an up-to-date review of the topic for those training or working as clinical chemists. Unfortunately, Dr. Papadoyannis has missed the mark with this volume. I assume that this is partly due to ignorance of what clinical chemists actually do. On page 91, for example, we are told that most routine clinical chemistry is now conducted using HPLC. While it is true that an increasing number of specialized assays are performed by HPLC, multichannel autoanalysers still reign supreme as far as ‘sample-crunching’ is concerned. Indeed, many common analytes (Nat-, HC03-) are not amenable to HPLC anyway. Part One (96 pages) aims to cover instrumentation but columns, retention mechanisms and even sample preparation are also discussed. Worthies such as Tswett get a mention but the references stop at 1986; many (most?) are from the 1970s.The mode adopted for reference citation is unhelpful; many are grouped (‘18-37’), no titles are given, and ‘repeats’ later in a chapter are given a new number. The full reference might be repeated in a later chapter. The text itself rambles. For example, three methods for barbiturates are given in Chapter 1 (Basic Principles), yet 20 pages are devoted to this topic in Part Two (Applications). Quaint terminology abounds. Thus, on page 4 we are told that solvent extraction is useful for ‘erasing’ interfering compounds. The arrangement of Figures is curious: most of the legend to Figure 5.1 (page 55), for example, is situated halfway down page 58.Chapter 8 (General Guide, 4 pages) consists of 2 pages of flow-sheets from Waters publications from 1983 and 1985 ... Is Part Two any better? The choice of applications chapters is an odd mixture for a book supposedly concerned with clinical chemistry: amino acids, alkaloids, antibiotics, aflatox- ins, barbiturates, carbohydrates, catecholamines, drugdstreet drugs, enzyme activity, lipids and lipoproteins, proteins, prostaglandins, steroids, tocopherols and vitamins-were they meant to be ordered alphabetically? Little on nucleo- sides, organic acids (such as oxalate), porphyrins, or aspects of therapeutic drug monitoring/toxicology (anticonvulsants, antidepressants, cardioactive drugs, cyclosporin, parace- tamol, salicylates, theophylline) of concern to clinical chem- ists.Hopefully someone will find these applications chapters useful, but much of the text and illustrations are lists of what others did with little attempt at interpretation. The references date up to 1988 (1989 for one of the author’s papers), although more recent ones cluster at the ends of chapters. Some are inappropriate: in Chapter 13, for example, we are referred to UK Office of Population Censuses and Surveys Mortality Statistics from 1980 for information on sample preparation for barbiturate analysis! There are many spelling and citation errors: ref. 63 (page 388), for example, cites Volume 123 of Analytical Biochemistry and then gives up the ghost. , The Index (8 pages) contains the usual vague (‘gear box’, ‘life span’, ‘liquid chromatograph’, ‘velocity’) and redundant [‘adrenaline’, ‘epinephrine’; ‘phenebarbitone’ (sic), ‘pheno- barbital’; ‘quinalbarbitone’, ‘secobarbital’] entries; there is also an alphabetical list of the headings of the applications chapters.All this without even bothering to criticize the quality of the information presented in the book: surely a pointer to someone else to do better. R. J . Flanagan ~~~ ~~ Biotransformations. Volume 3. A Survey of the Biotrans- formations of Drugs and Chemicals in Animals Edited by David R. Hawkins. Pp. 462. The Royal Society of Chemistry. 1991. Price f89.50. ISBN 8-85186-177-G. This third volume, in what has become an excellent series, more than lives up to expectations.The select group of leading scientists in the field of biotransformation, joined in this volume by Dr. D. Rance, have made another admirable attempt at collating and summarizing the 1989 literature dealing with the metabolism of various chemical entities in vertebrates, particularly mammals.220 ANALYST, FEBRUARY 1992, VOL. 117 The format of Volume 3 follows those of Volumes 1 and 2, and appropriately begins with a listing of key functional groups, plus an overview that draws attention to particular findings in investigations that represent more than just straightforward expansion of the general database. This highlighting of results describing novel metabolic pathways and stereoselective/stereospecific processes is to be com- mended, and is extremely useful to the reader.The overview might be enhanced still further if it were to include the identification of some examples of where particular biotrans- formations appear to demonstrate genetic polymorphism with important consequences. The body of the book describes the content of published articles on the biotransformation of chemicals ordered accord- ing to their class. In the vast majority the given precis of the results are of an appropriate length and give adequate detail. Whilst there is no doubt that it is the biotransformation data that are of the utmost importance, for some readers it would be additionally helpful if the experimental techniques used were described in a little more detail where they represent an extension of the generic use of the technique or are indeed truly novel.This inclusion would give completeness to the texts in the Volume, even though the reader is fully able to go to the original article if so desired, as the reference is given at the end of each summary. Volume 3 is a review of 1989 literature. It is, therefore, somewhat surprising to see reference to several articles published in 1988, especially to those appearing in readily accessible journals such as Xenobiotica, Biochemical Society Transactions and European Journal of Drug Metabolism and Pharmacokinetics. (There is even one from 1987, and, strangely enough, one from 1990!) The editor, and the RSC, are to be particularly congratu- lated for the additional information given at the back of Volume 3. Thus, there is now a Key Functional Group index, and it, together with the Compound Index, is cumulative across Volumes 1-3.These enhancements greatly improve the usefulness and speed of accessibility of the desired informa- tion contained in the Series thus far. Consideration might be given in future volumes to including also an alphabetical, but non-cumulative, list of the references cited. This is partly recommended because certain groups of workers have become associated with certain specialist areas of investiga- tion, and such a list would enable the reader to see quickly whether a contribution of theirs or of interest to them has been included in the volume. Finally, I would like to echo the thoughts of all scientists to whom biotransformation makes an important contribution to their working lives, by thanking the contributors to Volume 3 for their sterling efforts in its production, and state that we wait with eager anticipation for Volume 4.C. M . Kaye Spectroscopy of Biological Molecules Edited by R. E. Hester and R. B. Girling. Proceedings of the Fourth European Conference on the Spectroscopy of Biological Molecules, York, UK, September 1-6, 1991. Pp. xxiii + 464. The Royal Society of Chemistry. 1991. Price f 55.00. ISBN 0-851 86-437-6. If you want to find out what is going on at the forefront of research on spectroscopic studies of biological molecules, then this is a good book to browse. There is a lot going on: time-resolved X-ray diffraction, X-ray absorption, picosecond vibrational, and multidimensional NMR spectroscopy com- bined with molecular graphics, mechanics and dynamics, and more.The systems covered are also wide-ranging-from whole cells, photosystems and lipid membranes, to enzymes, proteins, DNA, drugs and co-factors. The articles are short conference abstracts, nearly 200 of them in all, many written in the style of papers. I am reading the book only one month after the conference was held-exactly the right timing for publication of material of this type. As you read the book that familiar conference-eve feeling comes over you: you can sense where the excitement is and your appetite is whetted for the detailed lectures that follow. But as the appendices are not full of videos (could such things be marketed?) all you can do is head for the library. The (camera-ready) papers provide a useful source of references for more detail about particular topics.They are too short themselves to provide it. The style of them is variable; some have no references at all. The book serves as a reminder that no one technique provides all the information required to solve real biological problems. We should employ a combination of methods with their different time and spatial resolutions. It is all too easy these days, given the sophistication of modern spectroscopic machinery, to become immersed in one’s own favourite technique and not appraise critically from time-to-time whether another would be better or add complementary information. This alone is a good reason for reading this book. The price is high for a book of conference abstracts; a soft cover would have done as the papers will certainly date quickly and be over-written by primary publications from the same authors.If the abstracts had been published as a supplement to an issue of a regular RSC journal they would have been guaranteed a place in all major libraries. At 255 they may not be. Peter J. Sadler Effects of Drugs on Clinical Laboratory Tests By Donald S. Young. Third Edition. Pp. ii + 944. American Association for Clinical Chemistry Press. 1990. Price $65.00 (AACC Members): $100.00 (Others). (Outside USA add $3.00 per book, postage.) ISBN 0-91 5274-53-1. The primary function of this directory is to alert the clinical chemist to the possible contribution of drug therapy to abnormal or unexpected test results. The increasing complex- ity of this subject is clearly illustrated by the major expansion and revision of this third edition compared with the previous lists published in 1975.New drugs and new laboratory tests continue to be introduced and the number of publications highlighting their interaction is also increasing. In an attempt to keep up with these developments the information has been stored on an extensive computer database from which this book has been compiled. It shares a common format with another complementary AACC publication: Effects of Disease on Clinical Laboratory Tests (2nd edn.), by R. B. Friedman and D. S. Young, AACC Press, Washington, DC, 1989. The directory is divided into four alphabetical sections and a numerical list. The first section is an index of laboratory tests and the second an index of drugs cross-referenced to relate generic names to proprietory names.The third section describes the effects by laboratory test and the fourth lists effects by drug. A similar format is used for entries in both of these sections, which form the main body of the work. Each entry lists drug name, body fluid and analyte measured. It also describes the mechanism of the effect where known, listing whether it is physiological, pharmacological or analytical and thereby affects the measurement procedure. Each entry includes a reference number and the fifth section is the list of these references. The editor is acutely aware of both the need for this information and the limitations of this format. The introduc-ANALYST, FEBRUARY 1992, VOL.117 221 tion draws attention to the contribution of drug metabolites and the parent compound. It notes that drugs are often given in combination, adding to the difficulties of interpretation. It also discusses variations in the metabolic processes of indi- viduals and the possibility that the disease process can modify response. It is also apparent that incomplete information is presented in many of the references, e.g., the concentration of drug at which the effect was observed is not stated, it is unclear if the effect was large enough to have clinical significance or the effects are only reported at non-physiological or inappro- priate drug dosage. Despite these significant limitations, this publication pro- vides a useful, reasonably contemporary, first source of references when laboratory results require cautious interpret- ation and is particularly relevant for the clinical chemist for whom it was intended.Computer databases are becoming increasingly valuable aids to laboratory and clinical diagnosis, understanding disease processes, and designing and monitor- ing appropriate therapy. Direct computer access to the database used for this compilation, and its integration into local systems, could make this work even more useful. Roger S . Ersser Phosphorimetry. Theory, Instrumentation and Applica- tions Robert J. Hurtubise. Pp. xii + 370. VCH. 1990. Price DMI 14.00; f45.00. ISBN 0-89573-749-3 (VCH Publishers); 3-52727-861 -3 (VCH Verlagsgesellschaft). This is an excellent and up-to-date text-book on phos- phorimetry.The author has presented a detailed survey of this technique since its inception and has competently discussed modern developments of phosphorimetry , which should be of interest to all researchers working in the field of luminescence spectrometry. This book should be considered as a very useful reference text. The first chapter presents an historical survey of phos- phorimetry and the photophysical phenomena of lumi- nescence are discussed in detail in Chapter 2. Chapter 3 gives a concise coverage of the instrumentation used in phos- phorimetry although this subject is also considered in other chapters of the book. A variety of important analytical parameters in phosphorescence measurements are very clearly discussed in Chapter 4. Instrumental aspects, sample preparation and the methodology of low-temperature phos- phorimetry are covered in Chapter 5 , which includes discus- sions on phosphorescence line-narrowing spectrometry.Chapters 6-10 discuss various theoretical and practical aspects of room-temperature phosphorimetry (RTP). Chapters 6-8 cover solid-surface RTP, Chapters 9 and 10 present sensitized and quenched RTP. The solid-surface technique is a new development in phosphorimetry and has great potential in analytical science. Chapter 11 presents briefly the applications of phosphorescence of proteins, polypeptides and peptides, and Chapter 12 discusses the use of the technique in polymer research. The final Chapter (13), discusses the future trends in phosphorimetry . The summary and consolidation of materials presented by the author in this text-book are certainly valuable and the book will be a useful addition to libraries and research workers in this and related fields.Although a few typographical errors appear in some of the common and useful equations, the quality of the book remains high. The publication of the book is timely and is to be welcomed, as is its reasonable price. R. Nara yanas wamy NMR, NQR, EPR, and Mossbauer Spectroscopy in Inor- ganic Chemistry R. V. Parish. Ellis Horwood Series in lnorganic Chemistry. Pp. 223. Ellis Horwood. 1990. Price f29.95. ISBN 0-13- 62551 8-3. This book aims at providing an introduction to the interpreta- tion of four types of spectra that have proved to be particularly useful in inorganic chemistry. The introductory chapter (15 pages) considers the various features that nuclear magnetic resonance, nuclear quadrupole resonance, nuclear gamma resonance (Mossbauer spectroscopy) and electron paramag- netic resonance have in common.The remaining chapters deal with each spectroscopic method in turn (NMR, 85; NQR, 17; Mossbauer, 40; and EPR, 35 pages). The techniques are introduced from scratch and are described primarily from a practical viewpoint. These four chapters follow a similar pattern. A consideration of the experimental conditions is followed by a simplistic account of the fundamentals of the method and a discussion of illustrative app1icatior.s. Each chapter concludes with a set of problems and answers of graded complexity. This is a well-written and eminently readable book that will be of considerable value to established workers in the inorganic field and to newcomers in this area.It lives up to its stated aim of providing guidance for the practising inorganic chemist. Its major emphasis is of course on ‘first-order’ phenomena and how to obtain chemical information from such spectra. The unravelling of more complex spectra receives little attention, but it cannot be otherwise in a treatment of four resonance techniques ab initio in 200 pages. Texts giving more comprehensive coverage of these topics are listed in the bibliographies. Relevant properties of NMR and NQR isotopes and of isotopes for Mossbauer spectroscopy are tabulated in appendices. The book is well produced and is good value for money by present-day standards. I recommend it to inorganic chemists and to teachers looking for advanced material for under- graduate courses.B. D. Flockhart Guide to Flow Cytometry Methods By W. McLean Grogan and James M. Collins. Pp. x + 228. Marcel Dekker. 1990. Price $99.75 (US and Canada); $1 19.50 (All other countries). ISBN 0-8247-8330-1. Flow cytometry is a fairly recent development in scientific terms and commenced with Coulter producing a device for counting cells, based on differing electrical conductivity between cells and the medium in which they were suspended, some 25 years ago. This book traces the development of the technique from then to its present state, with its many diverse applications. It is very good in presenting the theory and background to the subject, but the real strength of this book lies in its practical nature with its many applications, and is obviously based on the dedicated experience of the authors themselves.There are chapters on the production of single cell suspensions and DNA analysis with the emphasis on practical detailed methodology. Theory and application of light scattering and immunoflu- orescence are described, once again with specific methods. There are also considerations of intracellular pH, calcium and glutathione, followed by cell surface receptors and membrane potentials. For a small book it has a very extensive coverage of the subject and includes many procedures likely to be of use to222 ANALYST, FEBRUARY 1992, VOL. 117 workers in flow cytometry laboratories, including clinical and laboratory animal techniques.Indeed our own FACS labora- tory is waiting for me to release the book so that they can apply some of the techniques themselves. Being small, the book is essentially brief and it would benefit from a glossary; however, it is well referenced, has a useful appendix and extensive technical data. This, then, is an excellent book providing practical aid for the laboratory worker. It should be in every FACS laboratory but the price may put some people off. Nevertheless it is a book I would highly recommend. John F. Stevens Infrared Spectroscopy of Adsorbed Species on the Surface of Transition Metal Oxides By A. A. Davydov. Pp. xiv + 243. Wiley. 1990. Pricef65.00. ISBN 0-471-91813-X. This is the 1990 translation into English of A. A. Davydov’s book first published in Russian in 1984. The book substantially reviews the author’s work at the Institute of Catalysis at the USSR Academy of Sciences, Siberian Branch, much of it undertaken over a ten year span from the early 1970s to the early 1980s.As such, the book belies its rather general title, and is perhaps better regarded as a specialist treatise. The author begins by considering the spectral character- istics of active sites on oxide surfaces-hydroxyl groups, coordinatively unsaturated cations and surface oxygen-and discusses how far infrared spectroscopy can assist us in establishing the chemical properties of these centres by adsorption of simple probe molecules. A lengthy chapter is devoted to the characterization of the oxidation state of surface cations on a range of supported metal catalysts and transition metal exchanged zeolites by adsorption of CO and NO.This is followed by a discussion of the adsorption of alkenes on oxide surfaces, which begins by considering each of the separate structures that can arise on alkene adsorption. Finally, the author considers the applications of infrared spectroscopy to mechanistic studies of heterogeneous catalytic reactions. He succeeds in demonstrating the power of the technique when used in conjunction with other approaches, notably thermal desorption and ESR. Regarded as a specialist review, this book is valuable; the author’s painstaking and high quality work has done much to aid our understanding of the chemical reactivity of oxide surfaces, particularly in catalytic processes.The book contains over 400 references to the literature. Unfortunately, as there is a six year gap between publication of the original manuscript and this translation, most of the citations are to work that is now between 10 and 20 years old, much of it in Russian journals. A large part of the usually cited Western literature, for example on the partial oxidation of alkenes, is not included. Whilst the book will provide an excellent source of reference for the specialist, one wonders why Wiley, in preparing this translation for publication, did not take the opportunity to have the citations updated and widened. The author states clearly from the outset that he does not intend to discuss the technique of IR itself. However, the age of the original text is exposed by the author’s mention of the advent of FTIR in the penultimate paragraph of the book; although it is not stated, presumably all spectra shown were recorded with dispersive instruments.Although this does not detract from the quality of the data included, or the discussion and analysis of it, it adds to the specialist nature of the work. Viewed in the light of a specialist publication, the cover price is probably reasonable, but this is most certainly not a general text. Wendy R. Flavell Carbon, Nitrogen and Sulphur Pollutants and Their Determination in Air and Water By Jerome Greyson. Pp. xi + 338. Marcel Dekker. 1990. Price $99.75 (US and Canada); $119.50 (All other coun- tries). ISBN 0-8247-8235-6. With such an ambitious title, it might be doubted that a single book could achieve within 376 pages all that is implied.The cover claims, inter alia, that in a single volume it highlights new analytical methods, discusses the elementary chemistry of carbon, sulfur and nitrogen, considers the introduction of the elements into the biosphere through industrialization and energy use.. .and much more! It is perhaps unfortunate that rather than concentrating on the analytical methods, the author has used the first 120 pages io outline the history, nature and characteristics of carbon, nitrogen and sulfur pollutants in air and water. With such a wide subject area, this is inevitably a selective outline, which even takes the reader into the electron configuration of the elements. I fear that much of the detailed chemistry and biochemistry might make the book less attractive to engineers than the cover suggests.The target readership is the non-analytical chemist, although analytical chemists are included with a wide range of engineering professions, food scientists and both under- graduate and graduate students in various disciplines. This wide target and the wide scope of the subject matter within the title make it difficult to produce a really useful book for any single group or topic. In my view the book would have been better had the claims been met of being a practical reference detailing procedures available for the monitoring and control of carbon, sulfur and nitrogen pollutants. Although it cer- tainly reviews a range of analytical techniques, including several modern ones, it does not give practical details of procedures.Consequently, unlike other texts it is unlikely to be of use to those involved in the practice of environmental protection and seeking procedural guidelines. The greatest strength of the book is its inclusion of many of the more recent techniques of environmental analysis, such as immunoassays and ion chromatography. Care must also be taken in reading the book as the following two examples indicate: atmospheric CO2 is quoted as leading to a rise of about 1 K in the Earth’s average temperature; and in the limited section on sampling, despite much detail on the normal distribution, the point is not made that many environmental data are not normally distributed. Such points may limit the confidence of the reader in the content.A more limited range of content material, with concentra- tion on the traditional and newer analytical methods, would have made this text far more useful in a topical subject. R. S. Barratt _ _ _ _ _ _ _ _ ~ ~ ~ ~ Pesticide Residues in Food. Technologies for Detection By US Congress, Office of Technology Assessment, OTA Workshop Participants, March 14-16, 1989. Pp. 230. Technomic Publishing. 1989. Price SwFrl08.00. ISBN 0-87762-667-7. This report by the Office of Technology Assessment (OTA) was designed to provide a brief assessment of existing, new and emerging analytical technologies and methods to detect pesticide residues in foods for the US House Committee on Energy and Commerce. It consists of an eight chapter review accompanied by an appendix containing 13 specialist papers, grouped under theANALYST, FEBRUARY 1992, VOL. 117 223 heading of Research in Pesticides, which link-in with the main review. The review chapters are of somewhat mixed value.That on Federal Pesticide Residues in Food Monitoring Programmes makes interesting background reading but is probably of little importance to the majority of European analysts. The chapter on Contemporary Analytical Techniques makes a good introduction to pesticide residue analysis for non-specialists but contains a number of dubious statements such as: ‘the lack of r.r.t. data for capillary columns is a constraint to their use’; and ‘HPLC columns usually last longer because they are not subjected to the extremely high temperatures that GC columns are’.Similarly, AFID and NPD are discussed as though they are fundamentally dif- ferent. The chapters on Immunoassay and on Automation give good introductions to these topics and the chapter on Pesticide Analytical Methods gives a good overview of the needs of method development. Although the contents of this book are not what I would have expected for one entitled Technologies for Detection, it will find a useful place in my collection as background reading for non-specialists and for beginners in the art of pesticide residue analysis. G. M . Telling Instrumental Effects in Homodyne Electron Paramag- netic Resonance Spectrometers By R. Czoch and A. Francik. Ellis Horwood Series in Analytical Chemistry, Pp. 395. Ellis Howood. 1990. Price f45.00. ISBN 0-8531 2-795-6 (Ellis Howood); 0-470-20897- X (Halsted Press).The title of this book summarizes its contents well and, implicitly, many of its limitations. These limitations are aggravated somewhat by the delays that have occurred in its publication: a few of the references date from 1983, none is more recent. This is unfortunate, as the last ten years have seen great strides in instrumentation, particularly with regard to the use of computers. The book is divided into three parts. The first part, of three chapters, covers a brief introduction to the theory and practice of EPR. The first chapter discusses the basic theory of EPR, before going on to cover line profiles. This is followed by a discussion of the various parts of the instrument (and it is noticeable that the products of one manufacturer are featured prominently!).Finally, in the third chapter, there is a brief summary of the factors affecting precision and accuracy in EPR spectrometers. The second part of the book, consisting of five chapters, is an examination in much greater detail of the matter covered in Chapter 3. This part deals with via-phenomenon instrumental effects; distortions due to the unwanted effects on the signal of sample absorption and dispersion; receiver errors; back- ground; and a miscellany of other factors. In its two chapters, the third (and last) part of the book considers the choice of operating parameters, and methods of testing the performance of a spectrometer. It is again noticeable that the products of one manufacturer are prominent. The age of this book is its major defect-it is no longer timely.There is very little on the problems of digitized spectra, or ways of making the most of them. Pulsed EPR has grown up since this book was first conceived; EPR imaging is likewise too modern for it. Most of its material predates the computer revolution, which took place in the 1980s. As far as it goes though, it is useful. A very important question is, who will want to read this book? The answer is not obvious. It looks the sort of book to find on the shelf next to the instrument, but is it? If the instrument is a workaday spectrometer, then the users will be interested in getting good spectra out of it. They will not be unduly bothered about why the spectra are occasionally distorted--especially not in considerable mathematical detail.If the spectrometer is used more for research into EPR, then the users would probably want a more up-to-date book. Therefore, I suspect that the potential readership is rather limited, which is unfortunate, because there is some useful material in the book. The most-used chapters will, I suspect, be the last two, unless, of course, the system tests just happen to be very similar to those in the instrument manual! I suspect that the publishers have realized the problems, and have attempted to keep the costs down-at 245 for 400-odd pages it is not unduly expensive. However, cost saving has sometimes gone too far, for instance, why could they not justify the text on both sides of the page throughout, rather than only in the Preface? Furthermore, the binding is poor.I do not see a wide market for this book: I think it has missed its niche by several years. David Beveridge ~~ The Biochemistry and Uses of Pesticides. Structure, Metabolism, Mode of Action and Uses in Crop Protection By Kenneth A. Hassall. Second Edition. Pp. xviii + 536. VCH. 1990. Price DM1 28.00. ISBN 3-527-281 51-7 (VCH, Weinheim); 0-89573-976-3 (VCH, New York). Although recent legislation and registration requirements have improved safety there is currently considerable interest in the use and abuse of pesticides. Media attention has increased public awareness of the dangers of contamination of the environment and the possibility of toxic substances being present in food. This information packed book is a com- prehensive treatise on ‘The Biochemistry and Uses of Pesti- cides’.The author has collated and summarized a wealth of information on the structure, metabolism and mode of action of the enormous number of insecticides, fungicides and herbicides currently used in crop protection. The second edition summarizes the major developments in the biochemistry of pest control revealing the introduction of new groups of pesticides, which offer control where earlier compounds failed. Particular attention is given to recent developments in the understanding of the metabolism and breakdown of pesticides in the target organism, beneficial insects, crop plants and the environment. This information contributes to the selectivity and safety of these compounds and begins to answer the very necessary ecological questions now being posed on the environmentally friendly use of crop protectants.The book is written in three parts and contains 16 chapters, the first three setting the general scene on pesticide usage, safety, formulation, application and metabolism. The follow- ing six consider various aspects of organophosphorus, carba- mate, organochlorine and pyrethroid insecticides, including a chapter on the development and management of insect resistance. The next three chapters deal with fungicides and finally the last four chapters with herbicides. The strengths of the book lie in discussing the sheer variety of pesticides, grouping these into chemically similar compounds, comparing their mode of action and considering developments that enhance their effect under various environmental situations.The book considers in detail pesticide metabolism in the target organism, crop plant and soil , indicating the probable routes of degradation. The safety aspect of metabolic selectivity of224 ANALYST, FEBRUARY 1992, VOL. 117 recently developed pesticides with the increased knowledge of pest life-cycles is particularly highlighted. Reduced use of chemical pesticides within integrated pest management pro- grammes is now a genuine possibility resulting in a major reduction in input costs. The author rightly points to the difficulties in transferring these integrated systems to develop- ing countries, where it would transform the efficiency and safety of pest control, because of the lack of trained expertise in the field.For this reason alone the book provides a timely addition to the literature as a handbook for anyone involved in crop protection both in research and in the field. I found this book easy to read and well presented. There is a good balance between the general review and the factual content of the chapters with numerous schematic diagrams indicating the chemical structures and metabolism. It is the sort of book that, after purchase, becomes essential on the bookshelf as a standard reference or textbook. R. A . Cole ~ ~~~ Chromatographic Adsorption Analysis. Selected Works By Mikhail Semenovich Tswett. Ellis Horwood Series in Analytical Chemistry. Pp. 1 1 2. Ellis Horwood. 1990. Price f29.95. ISBN 0-1 3-1 32069-6. Chromatography, in its numerous modern variants, is the most widely employed of analytical techniques.By common consent, M. S. Tswett is seen as the inventor and this slim volume consisting of three of his innovative papers published between 1903 and 1906, his monograph of 1910 and brief biographical and historical appreciations by Professor Berez- kin leaves us in no doubt of the validity of this attribution. Of no less interest is Tswett’s list of relevant literature, which is not only considerable throughout the 19th century but also stretches back even to the work of Senebier (1782) and Lowitz (1790). The intense interest engendered by 19th century advances in recognition and understanding of physical processes capable of providing a basis for analysis can be judged from the fact that among the hundreds of names cited we find such giants of chemistry as Angstrom, Becquerel, Berthelot, Bunsen, Freundlich, Gibbs, Ostwald, Rayleigh, Stokes and Willstatter.Perhaps the most interesting name in the list is that of Borodin, remembered today for very different reasons! In Chapter I1 of his monograph Tswett summarizes five techniques for pigment separation that had been developed in the latter half of the 19th century and argues, correctly as we know, that all were inferior to his own ‘adsorption analysis’, which from about 1906 he had come to call chromatography. In Chapter VI he outlines partition theory in terms of distribution between immiscible phases and comments, a propos liquid-liquid distribution, ‘the separation of compounds with similar distribution coefficients would require a huge amount of initial solution and liquids, to say nothing of the time’. In subsequent chapters he elaborates on his view, first advanced in 1900, that the use of adsorptive columns gets around these problems, and illustrates his new technique with numerous examples of successful separations.His inventiveness does not end there, however, as he recognized the possibilities of the displacement in addition to those of the elution mode, he described the procedure of gradient elution, he identified the benefits of narrow columns and recognized that ‘fineness of powder is especially im- portant, since band broadening is obtained when grainy material is used.. .adsorption being coupled with diffusion in wide capillaries’. One could hardly have a clearer instruction on the eventual route to HPLC! Given that he had provided both a theoretical and a practical basis for the technique it is remarkable that chromatography subsequently lay fallow until its ‘re-dis- covery’ in 1930.Perhaps Ettre was right in his assessment that Tswett, a botanist by training and repute and hence not part of the (chemical) establishment, was simply ahead of his time, and so (his work was) doomed to non-acceptance. The volume provides a good read. The reader will learn little more about chromatography but will learn much about early scientists and the rocky path to scientific development and eventual acceptance of ideas and techniques. J. H. Purnell Computer Methods in UV, Visible and IR Spectroscopy Edited by W. 0. George and H.A. Willis. Pp. xi + 216. The Royal Society of Chemistry. Price f39.50. ISBN 0-85186- 323-X. This book is a little gem! Of course I may be biased, as it arrived on my desk at a time when I was struggling to convert a database of compressed JCAMP-IR files to a more easily manipulated form, and on leafing through the text it was a pleasure to find two chapters, well written and well presented, on this very topic. A more serious and devoted study of the book confirmed my initial impressions; this is a well prepared book and a delight to read. The importance and value of computer methods in modern analytical spectroscopy is well recognized and many books have been published in recent years dealing with this wide field of research and application. This book is different in that it is not a mathematical text or a list of algorithms or programs.It consists of 12 chapters, each an essay from different authors on a specific topic, which can be read independently. The material contained in the book is basically the text of lectures presented at the RSC Residential School of Wales in 1989. The main themes covered include computerized identification of materials from IR spectra using database matching and expert systems, data manipulation and combined (hyphen- ated) techniques, chemometrics and quantitative analysis and, in the final chapter, a discussion of the advantages and pitfalls of user written software. Chapter 1 provides an interesting historical background to the development of computerized spectroscopic analysis and, in its discussion of the ground rules of digitization of spectral data, should be read by anyone interested in computer interfacing. Chapter 2 moves on to examine data searching techniques.The requirements for a good spectral library are discussed and the problems of defining similarity of chemical structures are clearly explained. The use of a similarity matrix to assess search efficiency is also dealt with. Chapter 3 provides an overview of expert systems in particular EXSPEC, and their potential role in identifying materials from their spectra. Four further chapters are devoted to data manipulation, chemometrics and quantitative analysis. Simple procedures, such as spectra subtraction and smoothing, through to Fourier deconvolution and maximum entropy methods are all pre- sented.Spectroscopy and process control, including NIR analysis, has a chapter to itself, as does the topic of spectroscopic databases for HPLC. The style and presentation of the text in this book make it easy to read. The depth of treatment in all chapters I found to be right for this type of book and I would not hesitate to recommend this book to all students and practitioners of modern spectroscopic analysis. M. J . AdamsANALYST, FEBRUARY 1992, VOL. 117 225 Plasma Source Mass Spectrometry Edited by K. E. Jarvis, A. L. Gray, I. Jarvis and J. Williams. The Proceedings of the Third Surrey Conference on Plasma Source Mass Spectrometry, University of Surrey, 76-79 July, 7989. Pp. viii + 172. The Royal Society of Chemistry. Price €35.00. ISBN 0-851 86-567-4.Despite, or perhaps because it is currently one of the most active areas of analytical science, the vast majority of the published information on plasma source mass spectrometry is to be found in conference proceedings, many of which have very limited exposure, and primary journals. Books on the subject are still very scarce, although one or two more are likely to emerge soon. The publication of this slim volume by The Royal Society of Chemistry in its Special Publication series is, therefore, to be welcomed. The 12 papers it contains are based on nine of the 30 oral presentations and three of the posters given at the third of the highly respected and successful Surrey Conferences on Plasma Source Mass Spectrometry held at the University of Surrey, Guildford, UK, 16-19 July, 1989.Together they illustrate several of the areas in which fundamental research into inductively coupled plasma mass spectrometry (ICP-MS) , in particular, is being conducted and give a flavour of the range of applications of this sensitive, multi-element technique. The first two papers cover different modes of sample introduction, other than the typical nebulization of liquid samples. Both quote experimental data obtained with ICP- AES rather than MS detection, but which will nevertheless be of interest to ICP-MS users. Processes of Laser Ablation and Vapour Transport to the ICP are reviewed by L. Moenke- Blankenburg et al. , who provide a useful summary of some of the basic phenomena, such as laser-target interaction, cell design and transport processes, which are important in this attractive but problematic sample introduction technique.K. Dittrich et al. briefly discuss the Introduction of Microsamples into Plasmas using electrothermal vaporization (ETV), and compare results with those obtained by their FANES system. An example of the use of ETV as a means of improving the sample introduction efficiency is described by R. J. B. Hall etal. in their paper on The Feasibility of the Use of Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry for the Determination of Femtogramme Levels of Plutonium and Uranium in urine. From their Evaluation of ICP-MS for the Determination of Trace and Ultra-trace Elements in Human Serum after Simple Dilution, H. Vanhoe et al. were convinced that sample introduction using ETV had potential advantages over pneumatic nebuliza- tion for several elements via the reduction of polyatomic interferences.Isobaric overlap of analyte ion peaks by polyatomic ions arising from the plasma background and/or sample matrix are a serious limitation in some applications of ICP-MS to the determination of trace amounts of elements such as As, Se and Fe. The addition of a small amount of oxygen or nitrogen to the plasma has been reported to reduce such interferences. Results of their Investigations on Mixed Gas Plasmas Pro- duced using a Sheathing Device in ICP-MS are reported by D. Beauchemin and J. M. Craig. An alternative, mathematical approach to minimizing the effects of isobaric interferences in The Determination of Titanium, Copper, and Zinc in Geo- logical Materials by Inductively Coupled Plasma Mass Spec- trometry with Multivariate Calibration is described by M.E . Ketterer et al. They illustrate the use of multiple linear regression with both external calibration and standard addi- tions in the analysis of NIST Standard Reference Materials. Most of the few typographical errors in this book seem to be concentrated in the paper by R. C. Hutton et al. on Analytical Performance of Analogue Detection in TCP-MS and lead, for example, to the unfortunate claim that the upper working range of conventional pulse counting detection is precisely 106 counts s-1. Fallen superscripts aside, the authors make the important point that the performance of some of the latest ICP-MS instruments is such that the very sensitivity that made the reputation of the technique can now be a limitation. They describe the principles of a commercial analogue mode detection system that can be used in conjunction with pulse counting to extend greatly the potential analytical range. Sample preparation techniques for the analysis of biological material by ICP-MS are emphasized in two papers. E. J. McCurdy examined the use of open-dish digestion with nitric and perchloric acids for The Preparation of Plant Samples and Their Analysis by ICP-MS. T. Cho et al. reported A Basic Study on the Application of Tetramethylammonium Hydrox- ide (TMAH) Alkaline Digestion for the Determination of Some Volatile Elements by ICP-MS in which they established optimum ICP-MS operating conditions for the digested samples and concluded that the reagent had particular advantages in the determination of several volatile elements. Advantages in terms of speed and simpler sample prepara- tion in The Determination of Actinides in Environmental Samples by ICP-MS rather than by alpha-spectrometry were highlighted by J . Toole et al. Improvements in detection limits of about two orders of magnitude were expected by the use of ETV for sample introduction. J . A. F. Moore et al. described The Application of Inductively Coupled Plasma Mass Spec- trometry to the Analysis of Iron Materials and concluded that, apart from in the determination of germanium, polyatomic interferences derived from the matrix were largely insignifi- cant. Perhaps the most ‘heavyweight’ paper in this book is that by J. M. Richardson et al. on Re-0s Isotope Ratio Determina- tions by ICP-MS: a Review of Analytical Techniques and Geological Applications, which discusses many of the sample preparation difficulties and instrumental limitations that have to be overcome to obtain Re and 0 s isotopic ratios of acceptable precision for geochronological studies. Reproduction seems to have been largely from the pub- lisher’s high quality camera-ready copy and the editors have clearly taken pains to impose some consistency of layout and style across the contributions. The over-all effect is slightly marred by the longest paper being in a markedly different typeface. The inclusion of a subject index is most welcome. At f35 for a 172-page soft-cover book, it is not cheap, but then few things are in ICP-MS! Douglas L. Miles

ISSN:0003-2654    

DOI:10.1039/AN9921700219

出版商:RSC    

年代:1992

数据来源: RSC

摘要:

ANALYST, FEBRUARY 1992, VOL. 117 CUMULATIVE AUTHOR INDEX JAN U ARY-FEBRU ARY 1 992 Abdel-Hay, Mohamed H., 157 Abuirjeie, Mustafa A., 157 Aguilar Gallardo, A., 195 Analytical Methods Committee, Aydin, Hasan, 43 Barclay, David, 117 Boomer, Dave, 19 Bourgoin, Bernard P., 19 Brenes, Manuel, 173 Cacho, Juan, 31 Cai, Pei Xiang, 185 Campbell, Milford B . , 121 Chai, Fong, 161 Chan, Wing Hong, 18.5 Chang, Xi-jun, 145 Chknieux, Jean-Claude, 77 Coker, Raymond D., 67 Dinesan, Maravattickal K., 61 Edgar, Duart, 19 El-Din, Mohie Sharaf, 157 Evans, Don, 19 Ferreira, Vicente, 31 Gaind, Virindar S . , 9, 161 Gajendragad, M. R. ,203 Gao, Wen-yun, 145 GarcCa, Pedro, 173 Garcia Sanchez, F., 19.5 Garrido, Antonio, 173 97 Gatford, Christopher, 199 Hall, Tony, 151 Haswell, Stephen J.. 67, 117 He, Qong, 181 Hendrix, James L., 47 Hirayama, Kazuo, 13 Hu, Shengshui, 181 JuretiC, Dubravka, 141 Kageyama, Susumu, 13 Kalpana, G., 27 Kanert, George A., 121 KoroSin, Janez, 12.5 Koshy , Valsamma J., 27 Koiuh, Nevenka, 12.5 Lee, Albert Wai Ming, 185 Levillain, Pierre, 77 Lu, Jianmin, 35 Luo, Xing-yin, 145 Luterotti, Svjetlana, 141 Margielewski, Leszek, 207 Matsuoka, Shiro, 189 Miao-Kang, Shen, 137 Midgley, Derek, 199 MilaEiE, Radmila, 125 MilosavljeviC, Emil B., 47 Momin, Saschi A ., 83 Montagu, Monique, 77 Moreno Cordero, Bernardo, 215 Morikawa, Hidehiro, 131 Nakamura, Toshihiro, 131 Narayana, B., 203 Narayanaswamy, Ramaier, 83 Nawaz, Sadat, 67 Nelson. John H . , 47 Nerin, Christina, 31 NikoliC, Sneiana D., 47 Norris, John D., 3 Novozamsky, Ivo, 23 Oka, Hideyuki, 131 Padalikar, Sudhakar V., 75 Patil, Vitthal B., 75 Peddy, Rao V.C., 27 Pkrez Pavon, JosC Luis, 215 Petit-Paly, Genevieve, 77 Plambeck, James Alan, 39 Plaza, Stanislaw, 207 Powell, Mark J., 19 Preston, Brian, 3 Purdy, William C., 177 Ransirimal Fernando, Angelo, Rideau, Marc, 77 Rocheleau, Marie-Josee, 177 Ross, Lynn M., 3 Rusterholz, Bruno, 57 Sakai, Tadao, 211 Saleh, Hanaa, 87 39 227 Sanyal, Asis K., 93 Sato, Jun, 131 Schnekenburger, J., 87 Seiler, Kurt, 57 Sevalkar, Murlidhar T., 75 Simon, Wilhelm, 57 Staden, Jacobus F. van, 51 Stupar, Janez, 125 Su, Zhi-Xing, 145 Syed, Akheel A., 61 Tabuchi, Toyohisa, 189 Taha, Ziad, 35 Temminghoff, Erwin J. M., 23 Unohara, Nobuyuki, 13 Vohra, Kusum, 161 Waki, Hirohiko, 189 Wang, Joseph, 35 Wang, Kemin, 57 Warwick, Peter, 151 Willie, Scott, 19 Wu, Weh S., 9 Xiulin, Wang, 165 Yahaya, Abdul Hamid, 43 Yin-Yu, Shi, 137 yoshimura, Kazuhisa, 189 ZaniC-Grubisid, Tihana, 141 Zhan, Guang-yao, 145 Zhao, Zaofan. 181

ISSN:0003-2654    

DOI:10.1039/AN9921700227

出版商:RSC    

年代:1992

数据来源: RSC