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

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