Analytical comparison between standard and micro sample flow rate for the dilute-and-shoot analysis of glycerin samples by ICP OES

In this study, standard and micro sample flow rates (using the same nebulizer) were systematically investigated for the “dilute-and-shoot” determination of As, Ca, Cu, K, Mg, Na, P, Pb, and Zn in glycerin samples using inductively coupled plasma optical emission spectrometry (ICP-OES). The presence of glycerin affected the element determination by ICP-OES using lateral and axial views; the interferences could not be corrected with internal standards, regardless of the sample flow rates. The best selection of instrumental conditions for the trace-element determination in glycerin samples involved simple dilution of glycerin samples in HNO₃ 0.14 mol L⁻¹, followed by matrix-matching calibration and using Sc as an internal standard. The limits of detection were, in μg g⁻¹, 0.1 (As), 0.03 (Ca), 0.007 (Cu), 0.005 (K), 0.003 (Mg), 0.004 (Na), 0.2 (P), 0.1 (Pb) and 0.01 (Zn), while the short-term precision was lower 2.0 % for most analytes. Three samples of commercial glycerin were analyzed, and the method provided a robust and reliable approach for accurately quantifying impurities in glycerin, ensuring regulatory compliance and suitability for various industrial applications.