Validation and uncertainty estimation for multielement determination using ICP-OES according to the ASTM E2941-14 standard

Abstract

Standardized analytical methods for determining elemental concentrations require thorough validation and estimation of measurement uncertainty. Inductively coupled plasma optical emission spectrometry (ICP-OES) is a widely used technique for multielement analysis with the ASTM E2941-14 standard specifying the analytical conditions for its application. This study aims to validate the ICP-OES method and estimate the expanded uncertainty for multielement determination in accordance with ASTM E2941-14. Method validation and uncertainty estimation were conducted following Eurachem (2014) and Eurachem-CITAC (2012) guidelines, respectively. The method demonstrated acceptable linearity, with coefficients of determination (R2) ranging from 0.9972 to 1.0000 and correlation coefficients (R) from 0.9982 to 1.0000, exceeding the acceptance criterion (R2/R ≥ 0.995). Accuracy under repeatability conditions showed coefficients of variation between 1.0% and 8.0%, indicating good consistency. Trueness evaluation revealed no significant bias, with recovery rates within the acceptable range of 100% ± 10%. Combined uncertainty values ranged from 0.0425 (silver; Ag) to 0.5156 (scandium; Sc), corresponding to relative uncertainties of 1.25% to 8.16%, respectively. Expanded uncertainties ranged from 0.0850 (Ag) to 1.0312 (Sc). The dominant sources of relative uncertainty were associated with calibration curve-based concentration measurements and volumetric equipment.