Determination of arsenic in urine and feces by dry ashing, atomic absorption spectrometry.

A dry ashing flameless atomic absorption procedure was used to determine fish-arsenic in human urine and feces. Samples were dry ashed with Mg(NO3)2--MgO and dissolved in 6N HCl. Arsine was generated by the addition of NaBH4 and swept into a thermally heated silica tube furnace. Recoveries of several arsenic compounds added to samples ranged from 85 to 117%. The detection limit was about 3 ppb as for 10 g sample. Effects of the presence of common cations, anions and acids were studied.