Matrix isolation with an ion transfer device for interference-free simultaneous spectrophotometric determinations of hexavalent and trivalent chromium in a flow-based system

TALANTA

卷:164

Article

Ohira, Shin-Ichi¹  Nakamura, Koretaka¹  Chiba, Mitsuki¹  Dasgupta, Purnendu K.²  Toda, Kei¹ 

[1] Kumamoto Univ, Dept Chem, Chuo Ku, 2-39-1 Kurokami, Kumamoto 8608555, Japan

[2] Univ Texas Arlington, Dept Chem & Biochem, 700 Planetarium Pl, Arlington, TX 76019 USA

关键词: Electrodialysis;    Chromium;    Diphenylcarbazide;    Spectrophotometry;    Soil extracts;    Flow injection analysis;   

DOI  :  10.1016/j.talanta.2016.08.079

来源: Elsevier

【 摘 要 】

Chromium speciation by spectrophotometric determination of hexavalent chromium (Cr(VI)) with diphenylcarbazide (DPC) has several problems. These include: (1) the inability to directly detect trivalent chromium (Cr(III)) with DPC, (2) positive interference in Cr(VI) determination by other metal cations and (3) negative interference by any reducing agent present in the sample. These are addressed with an ion transfer device (ITD) in a flow injection analysis system. We previously developed the ITD for electrodialytic separations. Here we separate oppositely charged Cr(III) and Cr(VI) species by the ITD into two different acceptor solutions within similar to 5 s. The acceptor solutions consist of buffered H2O2 to oxidize the Cr(III) to Cr(VI). Then DPC is added to either acceptor to measure Cr(III) and Cr(VI) spectrophotometrically. The system was optimized to provide the same response for Cr(VI) and Cr(III) with limits of detection (LODs, S/N=3) of 0.5 mu g L-1 for each and a throughput rate of 30 samples h(-1). The ITD separation was also effective for matrix isolation and reduction of interferences. Potential cationic interferences were not transferred into the anionic Cr(VI) acceptor stream. Much of the organic compounds in soil extracts were also eliminated as evidenced from standard addition and recovery studies.

【 授权许可】

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