Determination of Total Arsenic by Batch Hydride Generation Atomic Absorption Spectrometry in...

Spectrochimica Acta Part B 57(2002) 2095–2102

0584-8547/02/$ - see front matter� 2002 Elsevier Science B.V. All rights reserved.PII: S0584-8547Ž02.00178-7

Determination of total arsenic by batch hydride generation atomicabsorption spectrometry in injectable drugs containing high levels

of Sb(V) asN-methylglucamine antimonate�

Erico Marlon de Moraes Flores *, Fabiana E. Barcelos da Silva ,a, a´

Eliane Pereira dos Santos , Favero Reisdorfer Paula , Juliano Smanioto Barin ,a a a´Renato Zanella , Valderi Luiz Dressler , Celso Figueiredo Bittencourta a b

Departamento de Quımica, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazila ´Departamento de Farmacia Industrial, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazilb ´

Received 17 May 2002; accepted 13 August 2002

Abstract

A procedure for the determination of arsenic by batch hydride generation atomic absorption spectrometry(HGAAS) in commercial samples of injectable drugs, containing high concentrations of Sb(V), is described. Theprocedure is based on the complexing effect for Sb of citric, oxalic and acetic acids as reaction media. Aqua regiawas used for sample digestion prior to As determination by HG AAS. The following experimental conditions for thedetermination of total As, as As(V), were evaluated: the acid medium and its concentration, sodium tetrahydroborateconcentration, purge time, and influence of the different oxidation states of As. The effect of the delay time aftermixing of sample and acid solution was also studied. Optimized conditions were: 10%(myv) citric acid, 1.5%(myv) sodium tetrahydroborate solution and 30 s for purge time. A delay time of 1 h was required after the digestedsample had been mixed with citric acid, before As determination could be carried out. No interference on As(III )and As(V) signals was observed in the presence of up to 1 mg Sb(V). The tolerance limits for Ni(II), Cu(II) andPb(II) were 1 mg, 100mg and 100mg, respectively. Recovery tests for As(III ) and As(V) resulted in values between97 and 101%. Characteristic mass and detection limit(3s), using the recommended conditions, were 0.52 and 0.8ng, respectively, for total As.� 2002 Elsevier Science B.V. All rights reserved.

Keywords: Arsenic determination; Hydride generation atomic absorption spectrometry; Sb(V) interference; Injectable drugs;Leishmaniasis

� This paper was presented at the 7th Rio Symposium on Atomic Spectrometry, held in Florianopolis, Brazil, April 2002 and is´published in the Special Issue ofSpectrochimica Acta Part B, dedicated to that conference.

*Corresponding author. Tel.:q55-16-261-5611; fax:q55-55-220-8054.E-mail address: [email protected](E.M. de Moraes Flores).´

2096 E.M. de Moraes Flores et al. / Spectrochimica Acta Part B 57 (2002) 2095–2102´

1. Introduction

Leishmaniasis is an inflammatory disease,occurring in tropical regions, which affects 12million people worldwide, and 1.5–2 million newcases of leishmaniasis are estimated to occurannually w1x. Leishmaniasis is endemic in someregions and it is generally treated with drugs basedon high concentrations of pentavalent antimony.Formulations based onN-methylglucamine anti-monate(‘meglumine antimonate’) are the drugsof choice, and over 2.5 million of ampoules arecommercialized per year in Brazil, where approx-imately 30 000 people are reported annually tosuffer from this diseasew2x. Drugs based onmeglumine antimonate are sold in ampoules of 5ml containing a nominal concentration of 85 000mg l of Sb(V).y1

Determination of inorganic impurities is of crit-ical importance in the quality control of drugs andmedicines because several trace elements havetoxic effects, and some of them could decrease thestability of active ingredients even at ultra-traceconcentrationsw3x. In this aspect, the determinationof low levels of arsenic is importantw4x, and itspresence in pharmaceutical products can be a riskfactor. Moreover, the presence of arsenic in par-enteral pharmaceutical dosage forms, such as meg-lumine antimonate, is critical because in this formits bioavailability in systemic blood circulation isstrongly increased in comparison to other forms ofapplication.Trace element contamination of drugs and their

intermediates may be introduced by several ways,such as through raw materials, reagents, solventsand equipment used for the synthesis. Many ofthese impurities can also be introduced after thesynthesis, and could be indicators of non-adequatehandling and storage or be used as fingerprints forthe source of drug raw materialw3x. All pharma-copoeias include a test for heavy metals, which iscommonly carried out by sulfide precipitation in aweakly acidic medium. The test should also besuitable for the determination of arsenicw5,6x, butit could be give consistent results only with dan-gerously high As concentrations. In recent years,the analytical control of injectable drugs hasbecome more important in view of improvements

in the production of pharmaceutical raw materialsand recent, more restrictive demands regardinglevels for toxic impuritiesw7x.

Hydride generation atomic absorption spectrom-etry (HG AAS) has been used thoroughly for thequantitative determination of arsenic in a varietyof samples. However, work related to the use ofthis technique for As determination in drugs isscarce. One of the limitations of HG AAS forarsenic determination in antimonial drugs is dueto the strong interference from the very high Sb(V)concentration(;85 000 mg l Sb). The interfer-y1

ence of Sb on As is a well known problem in HGAAS w8–10x. Dittrich and Mandryw11x found thatthe signal suppression was 10% for an As:Sb ratioof 1:1000, using a quartz tube atomizer. Narasakiand Ikedaw12x reported that a 500-fold excess ofantimony over arsenic could be tolerated withoutthe use of masking agents. Petrick and Krivanw13xfound that 1000mg of Sb completely suppressedthe absorbance signal of 50 ng of As(V). In viewof its complexing effect, citric acid, as well asother hydroxy-acids, have been used for speciationstudies for Sb(III ) and Sb(V) determination byHG AAS w14–17x. Moreover, citric acid is able tocomplex Sb speciesw17x and, in view of this, itsuse can be an alternative to minimize Sb interfer-ence on the determination of As by HG AAS.Based on the above, a procedure for determi-

nation of total arsenic in drugs used for leishman-iasis treatment containing very high levels ofSb(V) as meglumine antimonate is proposed. Theeffect of the reaction medium and other operatingconditions for As determination were investigated.The extent of interference caused by transitionelements was also studied. In this work the totalAs content was investigated to meet the specifi-cation of current pharmacopoeias. The optimizedprocedure was applied to the determination of Asin commercial lots of meglumine antimonate.

2. Experimental

2.1. Instrumentation

A Perkin-Elmer Model 3030 atomic absorptionspectrometer with deuterium background correc-tion, equipped with an arsenic hollow cathode

2097E.M. de Moraes Flores et al. / Spectrochimica Acta Part B 57 (2002) 2095–2102´

Table 1Figures of merit and analytical parameters for the proposed procedure for As determination in meglumine antimonate by HG AAS

Wavelength(nm) 193.7(bandpass 0.7 nm)Volume of 10% myv citric acid (ml) 10NaBH concentration(% myv)4 1.5Purge time(s) 30Integration time(s) 20Characteristic mass(ng) 0.51Limit of detection(absolute, 50ml), 3s (ng) 0.80Limit of detection in sample, 3s (mg l )y1 0.42Typical correlation coefficient 0.9988Linear range(ng) up to 125Contact time between 10%, myv citric acid and test solution(h) 1

lamp, operated at 18 mA, was used throughout.The equipment was coupled to a Perkin-ElmerMHS-10 batch hydride generation accessory.Argon (99.996%, White Martins, Brazil) was usedas purge gas. The quartz cell was periodicallycleaned by immersion in a 1.4 mol l HNOqy1

3

0.3 mol l HF solution for 30 s. Integratedy1

absorbance was used instead of peak height formeasurement. The analytical parameters are sum-marized in Table 1. Results for commercial sam-ples of meglumine antimonate were compared withthose obtained by using inductively coupled plas-ma optical emission spectrometry with convention-al nebulization(Perkin-Elmer Optima 2000 DV,using the conditions recommended by the manu-facturer and the 188.979-nm wavelength).

2.2. Reagents

All chemicals used were of analytical reagentgrade obtained from Merck(Darmstadt, Germa-ny). Concentrated nitric acid(65% myv) andhydrochloric acid(37% myv) were doubly dis-tilled in a subboilling still (Berghof Model BSP929, Germany). Milli-Q water (18.2 MV cm) wasused to prepare all solutions. All glass apparatuswere soaked in 2%(myv) HNO and 4%(myv)3

HCl for 48 h before using, and thoroughly washedwith water before use. Stock standard solutions,1000 mg l of As(III ) and As(V), were preparedy1

from NaAsO and Na HAsOØ7H O salts. Working2 2 4 2

solutions of As(III ) and As(V) were prepareddaily by dilution with 6 mol l HCl. Stock stan-y1

dard solutions, of 1000 mg l Sb(V) were pre-y1

pared by dissolving KSb(OH) in 6 mol l HCl.y16

Working solutions of Sb(V) were prepared dailyjust before use by an appropriate dilution with 6mol l HCl. Sodium tetrahydroborate solutionsy1

were prepared in water and stabilized with 1%myv NaOH. For interference studies, diluted solu-tions of Pb(II), Ni(II), Cu(II), and Bi(II) wereprepared from 1000 mg l stock solutions(Mercky1

Titrisol Cat. No. 109969, 109989, 109987 and�

109898, respectively).

2.3. Samples and sample treatment

In this work four lots of commercial samples(‘A’ and ‘B’ ) were analyzed, which are commer-cialized in ampoules of 5 ml, containing approxi-mately 85 000 mg l of Sb(V) as megluminey1

antimonate in aqueous solution. Sample aliquotsof 1 ml were digested with 8 ml of a 3q1 mixtureof conc. HCl and conc. HNO in 50-ml glass tubes3

in a digestion block at 1508C for 1 h. Aftercooling, sample digests were diluted with 6mol l HCl.y1

2.4. Procedure

In order to optimize the conditions for theproposed procedure some media for hydride gen-eration were studied for the determination of totalarsenic as As(V). Solutions with 50 ng As(V), 50ng As(V)q200mg Sb(V), and commercial samplesolutions with a nominal concentration of 85 000mg l Sb(V), spiked with 50 ng As(III ), werey1

investigated. Of the commercial samples, a volumeof digested solution correspondent to a mass of200 mg was placed into the reaction vessel. The


arsenic spike, as As(III ), in this solution was madebefore digestion. The influence of acetic, oxalicand citric acids(concentrations varying from 1 to20%, myv) on the As signal in the presence of Sbwas investigated as medium for hydride genera-tion. The influence of the contact time betweendigested sample solution and acid solution wasalso studied. The effect of the different oxidationstates of Sb on the signal of As(III ) and As(V)was investigated maintaining the amount of arsenicconstant and increasing the quantity of antimonyin the reaction vessel.

3. Results and discussion

3.1. Digestion of commercial samples of meglu-mine antimonate

The determination of As in samples with anSb(V) concentration of approximately 85 000mg l by HG AAS is not an easy task. In earliery1

experiments with solutions containing the equiva-lent of 200mg Sb(V), the signal for As, as As(V),was almost completely suppressed. The presenceof meglumine, a complexing agent, in commercialsamples could bring additional drawbacks due tofoam formation. A direct determination of As inthese samples by HG AAS, hence, is not possible,and a dilution of the solutions could impair thelimit of detection. An alternative could be to digestcommercial samples with a suitable medium,avoiding the precipitation of Sb oxidesyhydroxidesand to complex Sb species to prevent generationof stibine. In addition, if a wet oxidation step isapplied, foam formation is minimized and arsenicin the final solution is present in a defined oxida-tion state as As(V).Based on these aspects, a digestion procedure

was evaluated to decompose the meglumine incommercial samples. The conditions studied were:kind and amount of acid, temperature, time ofdigestion, and the recommended procedure was todigest 1 ml of commercial sample with a 3q1mixture of concentrated hydrochloric and nitricacids in 50-ml glass tubes heated at 1508C for 1h. After cooling, sample digests were diluted to20 ml with 6 mol l HCl, and aliquots of 50mly1

were used for subsequent studies, but higher vol-

umes up to 200ml could be used without changes.Spikes with As(III ) or As(V) solutions were madefor the final digested solutions(final concentrationof 1 mg ml ). The volume of 50ml of digestedy1

commercial solution corresponds to 200mg Sb(V)according to the nominal value for the drugs.Recovery tests with the addition of arsenic solutionas As(III ) were performed to evaluate the proposeddigestion procedure and the results were between98.9 and 100.3%.

3.2. Influence of acid medium on the As signal

Hydroxyacids have been used as reaction medi-um in the selective determination of antimonyspecies by HG AAS previouslyw14,16x. Relatedto this, the effect of 10% myv (concentrationarbitrarily chosen for initial tests) solutions ofacetic, oxalic and citric acids on the integratedabsorbance for As was investigated. The contacttime between solutions was varied from 1 to 24 h.Tests were made with 50 ng As(V), 50 ngAs(V)q200 mg Sb(V) solutions and digestedcommercial sample solutions spiked with 50 ng ofarsenic as As(III ). Acid solutions(10 ml) wereadded using an automatic volumetric syringe andthe total added volume of NaBH solution was 2.54

ml.Acetic acid has been suggested as medium for

the selective determination of Sb(III ), preventingstibine generation from Sb(V) w17x, and hencewas investigated in this study to minimize possibleinterferences on arsenic determination. However,in acetic acid medium results were strongly influ-enced by the presence of 200mg Sb(V) foranalytical and As-spiked digested commercial sam-ple solutions. In the latter, the arsenic signal wassuppressed by more than 90%, independent of thecontact time between 0 and 24 h.In the presence of oxalic acid the overall sensi-

tivity was approximately 10% better, and the Assignal was not influenced by the presence of Sbfor analytical As(V)qSb(V) solutions, independ-ent of the contact time studied. However, in theAs-spiked digested commercial solution, the Assignal was decreased, for all contact times studied,between 25%(immediately), and 5%(contact timeof 1 h).


Fig. 1. Influence of citric acid concentration on As determination by HG AAS(1.5% myv NaBH , 1 h delay time, 10 s purge time).4

Vertical bars are relative standard deviation(ns5).

The use of citric acid has been reported in theliterature as medium for studies concerning speci-ation analysisw14–16,18,19x. In this work, prelim-inary tests using citric acid were more promisingthan with the other acids. In the presence of 10%myv citric acid no difference was observedbetween signals for As(V) in matrix-free solutionand in the presence of 200mg Sb(V) for all timeintervals investigated. However, for the As-spikeddigested commercial sample solution, the signalwas 38% lower when the determination was madejust after citric acid addition. No difference wasobserved for the three solutions for contact timeof 1, 6 and 24 h, and the integrated absorbancesignals were approximately 0.44 s. The relativestandard deviation with all three contact times wasalways less than 5%. This might be related to thestrong complexing effect of citric acid on Sb(V)reported in Refs.w16,18x, as confirmed by otherauthors w19x. A contact time of 1 h before themeasurement was kept for all furtherinvestigations.First, the effect of citric acid concentration was

investigated, using solutions with 1, 5, 10 and20% myv citric acid. As can be seen in Fig. 1citric acid concentrations of 1 and 5% myv are

not sufficient to reduce the interference of Sb(V)on As from As(V)q200mg Sb(V) and As-spikeddigested commercial solution. Moreover, theresults with 1 and 5% myv citric acid were erraticand not very reproducible. For citric acid concen-trations of 10 and 20% myv, all integrated absorb-ance signals were practically the same and astandard deviation approximately 3% was observedfor all solutions. Thus, a concentration of 10% myv citric acid was chosen for subsequent studies.These results could be explained by a reaction ofcitric acid with Sb(V), maybe by bonding throughterminal carboxylic acid groupsw18x that couldcomplex inorganic Sb(V), minimizing the genera-tion of stibine.The influence of sodium tetrahydroborate con-

centration was investigated for As determinationby HG AAS using 10% myv citric acid with acontact time of 1 h. A dependence of the As signalon the reductant concentration between 0.5 and2% myv was observed. For all three investigatedsolutions: 50 ng As(V), 50 ng As(V)q200 mgSb(V) and 50 ng As-spiked digested commercialsolution, signals increased approximately 50% ingoing from 0.5 to 1.5% myv sodium tetrahydro-borate, and decreased 31% with a concentration of


Fig. 2. Interference of(a) Pb and(b) Bi, Cu and Ni on As signals by the proposed procedure(10% myv citric acid solution, 10 spurge time, 1 h delay time). Axis correspondent to interferent mass is in logarithmic scale. Vertical bars represent the relativestandard deviation(ns4).

2% myv NaBH . No background signals were4

recorded, and peaks were completely integratedwithin 15 s (a total integration time of 20 s wasused in this work). As the signals were very similarfor the three analyzed solutions, it appears thatthere is no difference in the overall process(gen-eration, transport and atomization) for the threesolutions under these conditions. No difference inthe As signal was observed either for purge timesfrom 15 to 45 s for all solutions.The pH value of the solutions after the addition

of citric acid was 1.6. At this pH stibine could begenerated from Sb(V) if the generation step wereonly a pH controlled process. However, it has notbeen observed in previous workw20x that thegeneration of SbH could be dominated by the3

complexation of Sb(V) with citric acid, and theeffect of pH would be limited to a minor role.Similar results have also been observed previouslyw16,21x.The nominal oxidation state of antimony in

meglumine antimonate is Sb(V). Moreover, underthe oxidizing conditions under which the digestionstep was performed, probably any Sb(III ) specieshas been converted to Sb(V). The influence of anincreasing mass of Sb(V) on both, As(III ) and

As(V) signals was investigated. A difference ofapproximately 55% between the overall sensitivityfor As(III ) and As(V) was observed, and theintegrated absorbance signals for 50 ng of the twospecies were 0.75 and 0.43 s, respectively. How-ever, practically no effect(-9%) was observedup to 1 mg Sb(V) added in reaction vessel forboth species. This fact is one more indicative forthe strong complexation of Sb(V) with citric acidin the liquid phase. These results were surprising,and to the knowledge of these authors there is noreport in literature concerning the determination ofAs in the presence of such high levels of Sb.

3.3. Influence of interferents

Some commercial lots of meglumine antimonatewere previously analyzed and results have shownthe presence of some contaminants such as Bi, Cu,Ni and Pb. Thus, an interference study was carriedout to make sure that these elements have noinfluence on the determination of As(V) by theproposed batch HG AAS procedure. It can be seenin Fig. 2 that up to 1000mg of Ni have noinfluence on the signals for As(V). For Cu and Bia small decrease was observed with masses higher


than 10 and 100mg, respectively. Lead caused amore pronounced decrease in the As(V) signal atmasses higher than 100mg Pb. The conditions forthe proposed procedure, especially for Ni, a well-known interferent on As determination by HGAAS, were considered suitable. The tolerance lim-its w22x for Sb(V), Ni(II), Cu(II) and Pb(II) were1 mg, 1 mg, 100 and 100mg, respectively. In theproposed procedure arsenic was determined asAs(V), and no prereduction step was attempted inview of the fact that reduction of As(V) to As(III )is generally more difficult than that of Sb(V) toSb(III ), and the generated Sb(III ) could interferemore strongly with the As determination.

3.4. Figures of merit

The developed procedure was suitable for arsen-ic determination by HG AAS in the presence ofhigh concentrations of pentavalent Sb in samplesof meglumine antimonate. Table 1 presents therecommended conditions for the proposed proce-dure. The linear range extended up to 125 ngAs(V), and a relative standard deviation of 2.8%was obtained. Recovery tests in commercial sam-ples were made by adding As(III ) analytical solu-tions to samples(corresponding to 5 and 25 ngAs in the final aliquots) before the digestion step.Arsenic was determined by the proposed procedureand recoveries were between 97 and 101%(ns5). With the proposed procedure the determinationof As in a high concentration of Sb(V), up to 1mg Sb(V), was possible without decrease of ana-lytical signals. This value is high when comparedto others procedures described in the literature.Four lots of commercial meglumine antimonate

solutions were analyzed using the recommendedconditions. Results for As concentration werebetween less than 0.48 and 1.27"0.08 mg l fory1

manufacturer ‘A’; the lots from manufacturer ‘B’were contaminated with As between 9.6"0.7 and78.9"2.7 mg l . These results were very similary1

to those obtained by inductively coupled plasmaoptical emission spectrometry after sample dilutionwith water, with an agreement between 98 and102.5%. As the meglumine antimonate is admin-istrated in an injectable form, the presence of Asis a high risk factor for people under treatment. In

view of this, arsenic control must be made rou-tinely to ascertain the quality of drugs used forleishmaniasis treatment.

Acknowledgments

Authors thank to FAPERGS, CNPq, Farmaco-peia Brasileira, ANVISA(to Dr Gonzalo Vecina´Neto) for supporting this study and to Dr Joao˜Alfredo Medeiros (UFRJ) for comments andsuggestions.

References

w1x World Health Organization, 27 March 2002. Availablefrom www.who.intyinf.fsyenyfact116.htm.

w2x Ministerio da Saude do Brasil, Manual de Controle da´ ´Leishmaniose Tegumentar Americana, FUNASA,Brasılia, Brasil, 1999.´

w3x A. Kelko-Levai, I. Varga, K. Zih-Perenyi, A. Lasztity,´ ´ ´ ´Determination of trace elements in pharmaceutical sub-stances by graphite furnace atomic absorption spectrom-etry and total reflection X-ray fluorescence after flowinjection ion-exchange preconcentration, Spectrochim.Acta Part B 54(1999) 827–833.

w4x D.L. Tsalev, Atomic Absorption Spectrometry in Occu-pational and Environmental Health Practice, Progress inAnalytical Methodology, vol. III, CRC Press, BocaRaton, FL, 1995, pp. 19–31.

w5x The United States Pharmacopeia 24th Revision, TheUnited States Pharmacopeial Convention, Inc., Rock-ville, MD, 1998, pp. 1856–1857.

w6x European Pharmacopeia, Maisoneuve S.A., 57 Saint-Ruffine, London, 1997, pp. 53–54.

w7x M. Wagner, P. Rostam-Khani, A. Wittershagen, C.Rittmeyer, B.O. Kolbesen, H. Hoffmann, Trace elementdetermination in drugs by total-reflection X-ray fluores-cence spectrometry, Spectrochim. Acta Part B 54(1997)961–965.

w8x B. Welz, M. Sperling, Atomic Absorption Spectrometry,3rd ed., Wiley-VCH, Weinheim, 1999, pp. 434–439.

w9x J. Dedina, D.L. Tsalev, Hydride Generation AtomicAbsorption Spectrometry, Wiley, Chichester, 1995, pp.193–195.

w10x P. Barth, V. Krivan, R. Hausbeck, Cross-interferences ofhydride-forming elements in hydride-generation atomicabsorption spectrometry, Anal. Chim. Acta 263(1992)111–118.

w11x K. Dittrich, R. Mandry, Investigations into the improve-ment of the analytical application of the hydride tech-nique in atomic absorption spectrometry by matrixmodification and graphite furnace atomisation. Part II.Matrix interferences in the gaseous phase of hydrideatomic absorption spectrometry, Analyst 111(1986)277–280.


w12x H. Narasaki, M. Ikeda, Automated determination ofarsenic and selenium by atomic absorption spectrometrywith hydride generation, Anal. Chem. 56(1984)2059–2063.

w13x K. Petrick, V. Krivan, Interferences of hydride formingelements and of mercury in the determination of anti-mony, arsenic, selenium and tin by hydride generationAAS, Fresenius Z. Anal. Chem. 327(1987) 339–342.

w14x M.B. Calle-Guntinas, Y. Madrid, C. Camara, Flow-˜ ´injection and continuous-flow systems to determineantimony(III ) and antimony(V) by hydride generationatomic absorption spectrometry, Anal. Chim. Acta 252(1991) 161–166.

w15x N. Ulrich, P. Schaked, D. Zilberstein, Speciation ofantimony(III ) and antimony(V) in cell extracts by anionchromatographyyinductively coupled plasma mass spec-trometry, Fresenius J. Anal. Chem. 368(2000) 62–66.

w16x B. Mohammad, A.M. Ure, J. Reglinski, D. Littlejohn,Speciation of antimony in a natural waters: the deter-mination of Sb(III ) and Sb(V) by continuous flowhydride generation-atomic absorption spectrometry,Chem. Spec. Bioavail. 3(1990) 117–122.

w17x Y.P. de Pena, O. Vielma, J.L. Burguera, M. Burguera,˜C. Rondon, P. Carrero, On-line determination of anti-´mony(III ) and antimony(V) in liver tissue and whole

blood by flow injection–hydride generation—atomicabsorption spectrometry, Talanta 55(2001) 743–754.

w18x A. Guy, P. Jones, S.J. Hill, Identification and chromat-ographic separation of antimony species witha-hydroxyacids, Analyst 123(1998) 1513–1518.

w19x J. Zheng, A. Iijima, N. Furuta, Complexation effect ofantimony compounds with citric acid and its applicationto the speciation of antimony(III ) and antimony(V)using HPLC–ICP-MS, J. Anal. At. Spectrom. 16(2001)812–818.

w20x E.M.M. Flores, E.P. Santos, J.S. Barin, R. Zanella, V.L.Dressler, C.F. Bittencourt, Determination of antimo-ny(III ) and total antimony by hydride generation atomicabsorption spectrometry in samples of injectable drugsused for leishmaniasis treatment, J. Anal. At. Spectrom.17 (2002) 819–823.

w21x M.B. Calle-Guntinas, R. Torralba, Y. Madrid, M.A.˜Palacios, M. Bonilla, C. Camara, A study of hydride´forming elements in the determination of As by hydridegeneration atomic absorption spectrometry and minimi-zation of Sb and Se interference bya-hydroxyacids andKI, Spectrochim. Acta Part B 47(1992) 1165–1172.

w22x J. Dedina, Interference of volatile hydride formingelements in selenium determination by atomic-absorp-tion spectrometry with hydride generation, Anal. Chem.54 (1982) 2097–2102.

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