DETERMINATION OF CARBARYL IN PESTICIDE FORMULATIONS BY FOURIER-TRANSFORM INFRARED SPECTROMETRY WITH FLOW-ANALYSIS

A procedure is proposed for the Fourier transform infrared spectrometric determination of carbaryl in pesticide formulations. The method is based in the dissolution of carbaryl in dichloromethane from solid powdered samples and direct measurement of the absorbance at 1747 cm-1 using a spectral baseline established from 1850 to 1650 cm-1. Absorbance measurements can be carried out in the continuous-flow or stopped-flow mode. In both instances the method provides accurate and reproducible results but the stopped-flow mode is the more sensitive. Under the optimum experimental conditions, for an optical pathlength of 1.0 mm and using five accumulated scans, the limit of detection obtained in the stopped-flow mode corresponds to 1.6 mug ml-1 of carbaryl. Real samples of powdered pesticide formulations containing carbaryl were analysed by the proposed procedure and the results were compared with those obtained by a reference spectrofluorimetric procedure.