Determination of toxic and non-toxic arsenic species in urine by microwave assisted mineralization and hydride generation atomic absorption spectrometry

Abstract

Flow injection — microwave oven — hydride generation — atomic absorption spectroscopy (FI-MO-HG-AAS) has been optimized for the determination 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 converted to arsenate, which is determined by HG-AAS to give the total concentration of the six species present in urine. The detection limits of 4–6 μg l^–1, the relative standard deviation of 3–7% and the high sample throughput make the methods suitable for rapid routine on-line determination. Application of the proposed procedures to the analysis of urine from people on a diet rich in seafood revealed a significant increase in total urinary arsenic due to the rapid excretion of organoarsenicals. Efficient decomposition and quantitative recovery of all arsenic species in spiked urine is achieved by using 5% K₂S₂O₈ in 5% NaOH at 4.6 ml min⁻¹, microwave power of 700 W and a 1.5 m coil.