Direct analysis of clay and refractory materials slurries by inductively coupled plasma optical emission spectrometry with axial viewing using the simplified generalized standard additions method

Abstract

The feasibility of clays and refractory materials analysis by direct introduction of slurries in an inductively coupled plasma optical emission spectrometry (ICP-OES) with axial viewing using the simplified generalized standard additions method (GSAM) was evaluated. The adopted approach is a multivariate extension of the conventional standard additions method, and uses two independent variables for determination of the analytes’ concentrations (the sample masses and the volumes of reference solutions added) and one dependent variable, the response. The relationship between the sample mass, volume of the reference solution added and the signal intensity is assumed to be linear. Concentrations of the analytes can be found either geometrically, from the slope of the two-dimensional response plane in a three-dimensional space, or mathematically from the ratio of the parameters estimated by multiple linear regression. Aluminium, Ca, Fe, K, Mg, Na, P, Si, and Ti were determined in clays and refractory materials slurries (10% v/v HNO₃) of certified reference materials. The software “Teach/Me” was used to fit the data. Aluminium oxide was detected in the 0.36–73.0%, CaO in the 0.03–2.13%, Fe₂O₃ in the 0.56–3.39%, K₂O in the 0.03–3.58%, MgO in the 0.06–0.47%, Na₂O in the 0.01–0.45%, P₂O₅ in the 0.05–0.13%, SiO₂ in the 22.2–98.42% and TiO₂ in the 0.06–1.95% range. Applying a paired t-test it was shown that all results were in agreement at a 95% confidence level with certified values. The application of GSAM was demonstrated as an effective method for the analysis of clays and refractory materials slurries.