The Effect of Complexity\nof a Matrix on Variation\nof Platinum Group Metal Determination Using ICP OES and Correction\nMethod: A Spent Catalyst as a Case Study

Recycling of platinum group metals (PGMs) from spent\ncatalysts\nis a promising alternative to the sustainable metallurgy of critical\nmetals, which requires an accurate and reliable analytical approach\nfor their determination. A potential microwave-assisted digestion\nand multivariate calibration procedure was investigated to determine\nthe PGM contents in various spent catalyst samples. The effect of\nseveral interelements (Al, Mg, Ce, and Na) was evaluated by the single\nfactor at once and multilinear regression models, which demonstrated\na significant variation in PGM determination using inductively coupled\nplasma optical emission spectrometry. The magnitude of effect due\nto these interferents can be −30% for Pt and Pd, and 20% for\nRh. The application of multivariate calibration was effective for\nPt and Pd determination from spent catalysts by reducing standard\nerror of prediction from >10% to <3.5% for Pt and 8.0% to 2.6%\nfor Pd; however, the effectiveness was more moderate for Rh. The crossed\ngage repeatability and reproducibility (GR&R) study showed a high\nvalue of contribution by part-to-part variation to the total variation\n(>98%) for all PGMs. Although the total GR&R contribution for\nRh determination 19.77% was higher than those of Pt and Pd (11.03%\nand 8.31%), the analytical procedure was acceptable as a reliable\napproach. Microwave-assisted digestion and multivariate calibration\nshowed efficient dissolution of the samples and less effects by interelements,\nwhich was suitable for investigating PGM-containing samples with a\ncomplicated matrix.