Determination of arsenic and antimony in geological materials by automated hydride generation and electrothermal atomic absorption spectrometry.

Abstract

A hydride generation-atomic absorption method for the rapid and precise determination of arsenic and antimony in geological materials is described. Samples (0.050.5g) were decomposed with perchloric, nitric, and hydrofluoric acids and potassium permanganate, and then evaporated nearly to dryness. The residue was dissolved by adding 20 ml of 6 M hydrochloric acid, 2 ml of 20 % potassium iodide, 5 ml of 10 % aluminium chloride, and 2 ml of 10 % ascorbic acid solutions. Arsenic or antimony hydride was generated with 1 % sodium tetrahydroborate, 2 M hydrochloric acid and 5 % malic acid solutions using an automated hydride generator, and introduced to a quartz cell atomizer. The limit of detection was 0.05 ppm for 0.5 g of the samples, and the relative standard deviation was smaller than 16 % for a content larger than 0.1 ppm. The time required for determining both arsenic and antimony in ten samples was about four hours. The method recommended here was successfully applied to the analysis of a variety of geological reference samples from the U. S. Geological Survey, Geological Survey of Japan, and National Bureau of Standards.