A technique for depositing iron, tungsten, molybdenum, and chrome in the determination of selenium and tellurium in alloy steel by ICP-AES method

Abstract

Direct determination of the content of selenium and tellurium impurities in metallurgical materials by the method of inductively coupled plasma atomic emission spectroscopy (ICP-AES) is difficult due to spectral and non-spectral interference from macrocomponents present in the materials under study. The separation of micro-(Se, Te) and macro-components (Fe, W, Mo, Cr, Cu, Ni, Co) through preliminary precipitation is the goal of the study. The use of barium acetate and sodium fluoride as precipitants are shown to provide an effective separation of Se and Te from Fe, W, Mo, and Cr (the content in the analyzed solution is less than 0.1 wt.% of the original) and partial separation from Cu, Ni, and Co (the content in the analyzed solution from 25 to 55 wt.% of the original). Optimal conditions for the deposition of macrocomponents (Fe, W, Mo, Cr) and inhibition of the process of coprecipitation of selenium and tellurium on sediments of macrocomponents for their subsequent ICP-AES determination were determined. The optimal pH for the precipitation of macrocomponents equals 1. The optimal mass of precipitants (barium acetate and sodium fluoride) is 10 and 3 g, respectively. To inhibit the process of coprecipitation of selenium and tellurium on sediments of macrocomponents, it is proposed to use hydrofluoric acid. The optimal volume of hydrofluoric and hydrochloric acids for inhibiting the process of coprecipitation of analytes on sediments of macrocomponents was determined (3 and 6 cm3, respectively). The developed procedure for separating micro-Se, Te from macro-components was tested on standard samples of alloyed steels using the «spike» method. The technique is characterized by satisfactory accuracy and reproducibility, the limit of determination of analytes after separation of macrocomponents is 10–3 wt.%.