Speciation studies by capillary electrophoresis and high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry

Capillary electrophoresis (CE) with direct on-capillary UV detection was applied along with four online sample preconcentration techniques for the simultaneous preconcentration and determination of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), antimonite [Sb(III)] and antimonate [Sb(V)]. These techniques were (i) sweeping-micellar electrokinetic chromatography (MEKC) with sodium dodecyl sulphate (SDS), (ii) large volume sample stacking (LVSS) with polarity switching, (iii) field-amplified sample stacking (FASS), and (iv) field-amplified sample injection (FASI) with electroosmotic flow (EOF) reversal using cetyltrimethylammonium bromide (CTAB). The lowest limits of detection (LOD) were obtained with FASI/EOF reversal with electrokinetic injection of the sample after a water plug. By combining this technique with high-sensitivity detection cell (HSDC), LODs for the target analytes were 2.1, 16, 14, 1.9, 1.1 and 13 µg L?1 for the six species, respectively. Compared to conventional capillary zone electrophoresis (CZE), this method gave improvement factors in LODs in the range of 0.6 ? 103?21 ? 103. The developed method was successfully applied for the speciation of arsenic and antimony in spiked tap water and recovery values in the range of 97.7?102.5% were obtained.Arsenic speciation in residents chronically exposed to inorganic arsenic via drinking water in Nevşehir area, Turkey, by HPLC?HG?AFS was a part of a research project for investigating carcinogenic risks of arsenic in those people. A methodology for arsenic speciation in urine by HPLC?HG?AFS was developed and presented. Inorganic [As(III), As(V)] and organic (DMA, MMA) arsenic species were separated on a strong anion exchange column under optimized chromatographic conditions (i.e., mobile phase 8.0 mM phosphate buffer at pH 5.8, flow rate 1.0 mL min?1, column at ambient room temperature, and using a C18 guard column). In order to assess accuracy of the speciation studies, ?SRM NIST 2669 arsenic species in frozen human urine? was analyzed for arsenic species by the developed method and the results were not different from the certified values at 95% confidence level. Total arsenic concentration was also determined by HG?AFS after acid digestion and pre-reduction with potassium iodide. The same procedure was applied to SRM 2669 at two levels (i.e., low and high) and the results were also in a good agreement. LODs with HPLC?HG?AFS, for a 100-?L injection loop, were in the range of 0.3?0.7 ?g L?1 and that with HG?AFS was 3 ng L?1 (at gain 100). Urine samples collected from the study area were analyzed. The results were classified into three groups as low, middle and high according to the arsenic level in drinking water people consumed. The mean values for the sum of arsenic species concentration and total arsenic were compared and were found to be statistically different from each other. It was also observed that in average DMA was the species with the highest concentration in the three groups, which was preliminarily attributed to methylation.