Simultaneous Kinetic Determination of Carbamate Pesticides after Derivatization withp-Aminophenol by Using Partial Least Squares

A method has been developed for the fast spectrophotometric determination of propoxur, carbaryl, and ethiofencarb in water samples using injection analysis in the stopped-flow mode. The method is based on the reaction betweenp-aminophenol and the phenolic compounds obtained from the pesticides, after a previous hydrolysis with 0.05MNaOH at room temperature for 15 min. The partial least-squares treatment of the spectrophotometry kinetic data provides a simultaneous determination of the three carbamate pesticides assayed with a relative accuracy error lower than 5% in complex mixtures also containing formetanate, which is only partially hydrolyzed under the experimental conditions and cannot be determined accurately by the above procedure.