Analysis of slags using laser-induced breakdown spectroscopy

The feasibility of laser-induced breakdown spectroscopy (LIES) for the analysis of gasification slags was investigated by comparing LIES results to the results of an ICP-OES analyzer. A small amount of slag sample was placed on a piece of double sided adhesive tape attached to a glass microscope slide and analyzed for Al, Ca, Fe, Si, and V which are major elements found in slags. The partial least squares regression (PLS-R) and univariate simple linear regression (SLR) calibration methods indicated that apart from V (accuracy up to +20%) the accuracy of analysis varies within 035-6.5% for SIR and 0.06-10% for PLS-R. A paired-sample t-test within the 95% confidence level yielded p-values greater than 0.05, meaning no appreciable statistical difference was observed between the univariate SIR with internal standardization and the multivariate PLS-R for most of the analytes. From the results obtained in this work, LIES response varies depending on the element and the technique used for quantitative analysis. Simultaneous use of the univariate calibration curves with internal standard (intensity ratio) and PLS regression in multi elemental analysis can help reduce the matrix effect of slags associated to their high variation in concentration. Overall, these results demonstrate the capability of LIES as an alternative technique for analyzing gasification slags. Estimated limits of detection for Al, Ca, Fe, Si and V were 0.167, 0.78, 0.171, 0.243 and 0.01 wt.%, respectively. (C) 2015 Elsevier B.V. All rights reserved.