SPECIATION DETERMINATION OF ARSENIC IN URINE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY WITH ONLINE ULTRAVIOLET PHOTOOXIDATION

A coupled system for arsenic speciation determination based on high-pe rformance liquid chromatography (HPLC), on-line UV photooxidation and continuous-flow hydride generation atomic absorption spectrometry (HGA AS) was built from commercially available modules with minor modificat ions to the electronic interface, the software and the gas-liquid sepa rator. The best results were obtained with strong anion-exchange colum ns, Hamilton PRP X-100 and Supelcosil SAX 1, and gradient elution with phosphate buffers containing KH2PO4-K2HPO4. The on-line UV photooxida tion with alkaline peroxodisulfate, 4% m/v K2S2O8-1 mol l(-1) NaOH, in a PTFE knotted reactor for 93 s ensures the transformation of inorgan ic Asm, monomethylarsonate, dimethylarsinate, arsenobetaine, arsenocho line, trimethylarsine oxide and tetramethylarsonium ion to arsenate. A bout 32-36 HPLC-UV-HGAAS runs could be performed within 8 h, with limi ts of detection between 2 and 6 mu g l(-1) As, depending on the specie s, The method was applied to the analysis of spot urine samples and ce rtified urine reference materials (CRMs), Upon storage at 4 degrees C, reconstituted CRMs are stable for at least 2 weeks with respect to bo th their total arsenic content and the individual species distribution .