MULTICOMPONENT STANDARD ADDITIONS AND PARTIAL LEAST-SQUARES MODELING - A MULTIVARIATE CALIBRATION APPROACH TO THE RESOLUTION OF SPECTRAL INTERFERENCES IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

Spectral interferences in graphite furnace atomic absorption spectrometry (GFAAS) represent a considerable problem, often making the direct determination of certain elements in specific matrices impossible, particularly when continuum source background correction is employed. The possibilities to resolve such spectral interferences mathematically by applying multivariate calibration have been investigated. Resolution is achieved using multi-component standard additions (the so-called generalised standard addition method or GSAM) combined with partial least squares (PLS) modelling. This multivariate calibration method, PLS-GSAM, is described and its use illustrated by application to the GFAAS determination of gold in the presence of cobalt at the 242.8 nm wavelength, where severe spectral interference problems are observed using continuum source background correction. Two requirements for the successful application of PLS-GSAM are that the sample constituent causing the spectral interference is known and that its concentration can be increased by standard additions. It is shown that more accurate results are obtained by PLS-GSAM than by conventional (single-component) standard addition methods. © 1990.