Abstract

Univariate and multivariate (partial least squares 1, PLS1) calibration techniques are compared for the determination of Pt, Pd and Rh in a complex sample matrix. The univariate techniques utilised either pure standards, pure standards with interelement correction factors applied, or matrix matched standards. Univariate calibration yielded relative root mean square errors (RRMSEs) of prediction for Pt, Pd and Rh of 19, 15, and 54% and 13, 18, and 88% for test solutions and real samples, respectively. Univariate calibration with matrix matching proved the most accurate method with RRMSEs for Pt, Pd and Rh of 2.5, 3.7 and 2.4% for a series of synthetic test solutions, and 12, 2.3 and 8.0% for real samples, respectively. In comparison, the multivariate calibration method yielded relative root mean errors for Pt, Pd and Rh of 5.8, 3.0 and 3.5% in the test solutions, and 32, 7.4 and 76% in the real samples. The relative error for the matrix matching and PLS1 techniques was dependent upon analyte concentration.