Method validation and uncertainty evaluation in trace element analysis of high-purity silver by ICP-OES

Silver is a precious metal, and high-purity silver is widely used in electronic, optical, and reference material applications, where even trace amounts of impurities can critically impact performance and accuracy. Quantifying trace elements such as Cu, Pb, Fe, and others in high-purity silver poses analytical challenges due to the potential matrix effects and the need for accurate calibration strategies. The trace impurities, Cu, Fe, and Pb in high-purity silver samples were quantified using the standard addition (SAM) and the matrix-matched external standard method (MMESM) using inductively coupled plasma optical emission spectrometry (ICP-OES), and their results are compared. The research also includes a comprehensive uncertainty evaluation associated with each method. Validating parameters like LOD (Limit of Detection), LOQ (Limit of Quantification), working range, accuracy, and precision are also discussed in detail in the manuscript. The results obtained from both the calibration approaches were found to be comparable. Both methods were found to have the ability to account for the matrix effect. The recovery found for the results indicates that both methods provide reliable quantification. The two-way ANOVA results demonstrate that both emission lines and matrix concentrations yield statistically comparable results for copper, iron, and lead determination by SAM & MMESM. Two extra emission lines for copper and one for iron estimation were observed and are reported here. Also, the results for both SAM and MMESM with and without internal standard correction were quantified, and the results were almost the same. Thus, this work provides a comprehensive understanding of trace element analysis in silver, which can also be extended to other metals for trace element analysis.