Inexpensive, simple hydride generation system with minimum interferences for the atomic-absorption spectrophotometry of arsenic

Abstract

A system for the hydride generation atomic-absorption spectrophotometry of arsenic is described that uses ordinary boiling-tubes to hold the acidified samples into which sodium tetrahydroborate(III) solution is injected and the evolved hydrogen carries the generated arsine directly through the spectrophotometer nebuliser to a nitrogen-supported hydrogen flame. The total arsenic evolved is measured by integrating the absorbance for 16 s. Apart from transition metals of the cobalt, nickel and copper groups, the arsenic response appears to be insensitive to interferences, and the effects of these metals may be overcome by adding 0.5 g of thiourea to each sample. The limit of detection (95% confidence) is about 6 ng of arsenic and the reproducibility is about 1% for 0.5 µg of arsenic.