Chemical generation of arsane and methylarsanes with amine boranes. Potentialities for nonchromatographic speciation of arsenic

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DOIResolve DOI: http://doi.org/10.1021/ac4032466
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TypeArticle
Journal titleAnalytical Chemistry
ISSN0003-2700
Volume86
Issue3
Pages15991607; # of pages: 9
SubjectAtomic spectrometry; Certified reference materials; Dimethylarsinic acids; Experimental conditions; Generation process; Hydride generations; Monomethylarsonic acids; Selective determination; Amino acids; Atomic spectroscopy; Chemical analysis; Chemical speciation; Hydrides; Process control; amine; arsenic; arsine; organoarsenic derivative; water; fractionation; isolation and purification; methodology; Chemical Fractionation
AbstractThe efficiency of chemical generation of arsanes from inorganic arsenic, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA), to arsane, AsH3, monomethylarsane, CH3AsH2 (MMA), and dimethylarsane, (CH3)2AsH (DMA), has been investigated in different reaction media with the aim to better elucidate the mechanisms controlling their generation process and to find the experimental conditions to implement a nonchromatographic arsenic speciation analytical method, which is based on the selective determination of some arsenic species. Studies were performed by continuous flow hydride generation coupled with atomic spectrometry (CF-HG-AS), using different reductants such as borane-ammonia (AB), borane-tert-butylamine (TBAB), and sodium tetrahydridoborate (THB) in HCl and HClO4 media, in the presence or absence of l-cysteine (Cys). The efficiency of HG processes for MMA and DMA is mainly controlled by the reactivity of the substrates with the borane, which could be strongly influenced by the formation of ion couples. The protonation of arsane did not play a significant role in the employed reaction system. By taking advantage of the different reactivity pattern of As species in selected generation conditions, DMAA and MMAA could be selectively determined in 0.5 and 10 M HClO4 solutions, respectively, in the presence of Cys, with AB as the reducing agent. The presence of Cys as a masking agent and the peculiar reducing properties of AB ensured a good control of interferences, as far as it has been observed for Co(II), Ni(II), Cu(II), Fe(II), Fe(III). The overall time needed to complete the prereduction step has been verified for MMAA and DMAA at different acidities in order to achieve the best selectivity. The selective determination of DMAA with AB/Cys in HClO4 has been optimized and applied to certified reference materials (CRMs) of natural waters CASS-4, SLRS-4, and NASS-4 (NRCC). The estimation of DMAA concentration allows us to correct the concentration of As(III) for the interference of DMAA in the selective determination of As(III) according to a selective HG method recently reported.
Publication date
PublisherACS Publications
LanguageEnglish
AffiliationNational Research Council Canada; Measurement Science and Standards
Peer reviewedYes
NPARC number21272714
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Record identifier90aca75b-91c2-449d-84ad-c99f133c1c88
Record created2014-12-03
Record modified2016-05-09
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