ONLINE PRECONCENTRATION AND FLOW-ANALYSIS FOURIER-TRANSFORM INFRARED DETERMINATION OF CARBARYL

A new strategy to improve the limits of detection in Fourier transform Infrared (FTIR) has been developed. The proposed method consists of p reconcentration of samples, using conventional solid phase extraction cartridges, and online elution with dichloromethane. Absorbance measur ements are obtained by FTIR. Carbaryl has been used as a test molecule with on-line measurements carried out at 1746 cm(-1). This procedure permits (i) field sampling, (ii) stabilization of pesticides, and (iii ) fast determination of carbaryl in the laboratory. The sensitivity ob tained with this procedure corresponds to 0.0444 area units mu g(-1) c m(-1), and the limit of detection, to 15 mu g of carbaryl, which, for a sampling volume of 1 l, corresponds to 15 mu g l(-1) of this pestici de. The reproducibility of three independent analyses of a well water sample containing 195 mu g l(-1) of carbaryl corresponds to a relative standard deviation of 8.6%.