MULTICOMPONENT DETERMINATION OF THE PESTICIDE NAPTALAM AND ITS METABOLITES IN RIVER WATER, BY APPLYING PARTIAL LEAST-SQUARES CALIBRATION TOTHE DERIVATIVE SPECTROPHOTOMETRIC SIGNALS

A multivariate calibration method, partial least squares (types PLS-1 and PLS-2), was applied to the simultaneous determination of naptalam (N-(1-naphthyl) phthalamic acid) and its metabolites N-(1-naphthyl) ph thalimide and 1-naphthylamine in mixtures by UV-visible absorption spe ctrophotometry. The absorption and first-derivative absorption spectra of mixtures were used to perform the optimization of the calibration matrices by the PLS method. Two different experimental designs for the three-component mixtures are assayed and the results are discussed. T he proposed method with the derivative spectra was applied to the dete rmination of these analytes in river water at the ppb level.