Determination of trace concentrations of arsenic in nickel-base alloys by electrothermal atomic absorption spectrometry

Abstract

A procedure for the determination of trace concentrations of arsenic in nickel-base alloys was developed. Solid samples of nickel-base alloys were decomposed with a mixture of hydrochloric acid and nitric acid (4 + 1), the resulting solution was heated nearly to dryness and the residue was dissolved in about 2 ml of distilled, de-ionized water. Most of the excess of the acids was removed by repeating the heating and dissolution procedures. The final solutions were analysed by electrothermal atomic absorption spectrometry using a pyrolytic graphite platform in a pyrolytic graphite coated graphite tube at 193.7 nm. Various pre-treatment conditions, which included chemical modifiers, hydrazine and potassium iodide, were evaluated. Potassium iodide gave satisfactory results. The accuracy of the analytical results was checked using certified reference materials. The optimum conditions that gave the highest precision and accuracy of the results were established.