DETERMINATION OF TOXIC AND NONTOXIC ARSENIC SPECIES IN URINE BY MICROWAVE-ASSISTED MINERALIZATION AND HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY

Flow injection - microwave oven - hydride generation - atomic absorpti on spectroscopy (FI-MO-HG-AAS) has been optimized for the determinatio n of the total and toxic arsenic in urine with and without persulfate, respectively. With microwave oven assisted digestion of urine with 5% (w/v) K2S2O8 and 5% (w/v) NaOH all arsenicals completely can be conve rted to arsenate, which is determined by HG-AAS to give the total conc entration of the six species present in urine. The detection limits of 4-6 mu gl(-1), the relative standard deviation of 3-7% and the high s ample throughput make the methods suitable for rapid routine on-line d etermination. Application of the proposed procedures to the analysis o f urine from people on a diet rich in seafood revealed a significant i ncrease in total urinary arsenic due to the rapid excretion of organoa rsenicals. Efficient decomposition and quantitative recovery of all ar senic species in spiked urine is achieved by using 5% K2S2O8 in 5% NaO H at 4.6 ml min(-1), microwave power of 700 W and a 1.5 m coil.