Rapid Atomic Absorptiometric Determination of a Small Amount of Arsenic in Biological Samples : By Arsine-Argon·Hydrogen Flame System

Abstract

An atomic-absorption spectrophotometry for rapid, sensitive, and precise determination of arsenic in biological samples is described. Arsine can be rapidly evolved from arsenic solution in 2 N hydrochloric or sulfuric acid by using zinc powder tablets together with potassium iodide and stannous chloride solution as the reductant. Thus, arsenic can be determined by atomic-absorption spectrophotometrically by introducing arsine into an argon-hydrogen flame and reading the absorption signal of arsenic at 1937 Å. To obtain optimum conditions for the determination of arsenic in biological samples, various factors were examined. The optimum range of acidity was about 1.5-3 N in hydrochloric acid when potassium iodide and stannous chloride concentrations were kept at 1.6% and 0.8%, respectively. The addition of at least one piece of zinc tablet (about 0.5 g) was enough to obtain the highest and constant recovery of arsenic as arsine. The sensitivity of the method for 1% absorption was evaluated to be 0.7 ppb of arsenic and linearlity of the absorption vs. concentration was good up to 1μg/20 ml (50 ppb). Effect of several ions on the method was also examined. Satisfactory results were obtained by applying the proposed method to the analysis of arsenic in several biological materials, which were previously digested by a conventional method using sulfuric-nitric acid mixture.