USE OF PARTIAL LEAST-SQUARES MODELING TO COMPENSATE FOR SPECTRAL INTERFERENCES IN ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY WITH CONTINUUM SOURCE BACKGROUND CORRECTION .1. DETERMINATION OF ARSENIC IN MARINE-SEDIMENTS

When arsenic is to be determined in samples containing aluminium, such as sediments, by electrothermal atomic absorption spectrometry (ETAAS) at the most sensitive line (193.7 nm), spectral interferences occur when continuum source background correction is used. In this work, the possibilities of resolving the spectral interference from aluminium mathematically using multivariate calibration have been investigated. A calibration set consisting of arsenic and aluminium standard solutions, and mixtures of the two, is analysed by ETAAS and the absorbance signals obtained are used to construct a partial least squares model. This model is then used to predict the arsenic (and aluminium) concentrations in dissolved sediment samples from their absorbance signal patterns. The multivariate calibration method employed is described, and results for the determination of arsenic in two marine sediment reference materials are discussed.