Determination of major to trace level elements in Zircaloys by electrolyte cathode discharge atomic emission spectrometry using formic acid

Abstract

An electrolyte cathode discharge atomic emission spectrometry (ELCAD-AES) method using formic acid is described for the determination of major to trace level of the elements Ni, Co, Fe, Mn, Mg, Cu, Cr, Pb, Ca in Zircaloys. The influence of HCOOH and CH₃COOH to improve the sensitivity of ELCAD-AES for analyte determination is investigated. Sensitivity of ELCAD-AES was significantly improved with HCOOH for the determination of these elements. 20% (v/v) HCOOH was found to produce a maximum enhancement in the sensitivity of ELCAD-AES for the analytes. With 20% (v/v) HCOOH, improved detection limits were determined for Ni (5 ng mL⁻¹), Co (9 ng mL⁻¹), Fe (16 ng mL⁻¹), Mn (7 ng mL⁻¹), Mg (5 ng mL⁻¹), Cu (6 ng mL⁻¹), Cr (65 ng mL⁻¹), Pb (10 ng mL⁻¹), and Ca (8 ng mL⁻¹). The improvement is 2-fold for most elements, 5-fold for Pb, and essentially unchanged for Cr. The use of HCOOH enabled the direct determination of analytes in Zircaloys by ELCAD-AES. The method has been validated by determining the concentrations of analytes Ni, Co, Fe, Mn, Mg, Cu, Cr, Pb, Ca in a Zircaloy certified reference material (Zircaloy-4 NIST-360b) and also in a Zircaloy sample which was analysed by glow discharge quadrupole mass spectrometer (GD-QMS). The precision expressed as a percentage relative standard deviation of signals of multiple analyses (N = 4) of the ELCAD-AES method was found to be between 2 and 10% for major (>0.1 wt%) and minor level (<0.1 wt% and >100 μg g⁻¹) elements and 10–15% for trace level (<100 μg g⁻¹ and >10 ng g⁻¹) elements. Depending on the levels of the impurities the relative error in accuracy of the ELCAD-AES method was found to be between 3 and 20%.