Determination of Ag in high-purity solutions of copper and nickel by high-resolution continuum-source electrothermal atomic absorption spectrometry (HR-CS-ETAAS)

Abstract

A need to control the silver content in high-purity copper and nickel samples is attributed to the deterioration of the technical characteristics of materials when the presence of such impurities exceeds the permissible levels. In this study, modes for the determination of Ag in copper and nickel by high-resolution electrothermal atomic absorption spectrometry with a continuum source at a content of 10–6 – 10–5 % have been developed. The optimal temperature regimes of the atomizer program and the amount of chemical modifier introduced were developed proceeding from the results of studying the regularities of atomic absorption measurements of silver in matrix solutions of Cu and Ni (with a concentration of 10 g/liter each). To construct calibration dependences, aqueous standard solutions of the analyte (determination in copper) and aqueous standard solutions of the analyte with the addition of nickel nitrate 10 mg/liter (determination in nickel) were used. The atomization temperature was chosen to be 1600°C. The dosing volume of the solutions in the graphite furnace was always 20 μl. When determining Ag in high-purity copper, different temperatures of the pyrolysis stage were used for measurements with dosing of standard analyte solutions (600°C) and for measurements with dosing of the analyzed copper solution (800°C). In the determination of silver in nickel solutions, the temperature of the pyrolysis stage was 800°C. The developed conditions for the determination of silver were tested in the analysis of high-purity samples of copper and nickel (standard solutions of Inorganic Ventures, USA with a concentration of 10 g/liter) using spiked tests. The maximum value of the relative error of determinations does not exceed 13%. The detection limits for silver were: 1.8 × 10–6 % in copper and 3.2 × 10–6 % in nickel.