Determination of ppb Level of Arsenic in Water by Atomic Absorption Spectrometry using Zinc Column Method

Abstract

An improved determination system for arsenic was developed by using the apparatus of the hydride generator. The optimum concentration of reducing agents was 4-8 N hydrochloric acid, 0.1-0.5% potassium iodide, and 0.015-0.3% stannous chloride. Evolution of arsine was quantitative in the range of 40-75° of the zinc column. Sensitivity of this method for 1% absorption was evaluated to be 0.8 ppb of arsenic and a calibration curve obtained was linear up to 2.0 μg of As/50 ml. Coefficients of variation in the determination of 0.6 and 1.5 μg of As/50 ml were 3.9% and 2.35%, respectively, in the runs. The recovery of arsenic added to hot-spring, river, and sea water was 93-100%, with a relative standard deviation of 2.35%. Presence of most metal ions in the sample did not interfere in the determination of arsenic by this method, while selenium (IV), even at concentrations as low as an amount equal to arsenic, interfered in the determination of arsenic.