In situ fluorimetric determination of pesticides on vegetables

A new method for in situ pesticide quantitation is reported. Direct measure ment of two pesticides (methoxychlor and N-(phosphonomethyl)glycine) spiked onto vegetables, has been carried out. The contaminant is detected by spra ying the substrate with a probe solution of Nile Red and measuring the resu lting solid state fluorescence. A portable, optical fiber-interfaced fluori meter was constructed for this application. Glass and eggplant peel were us ed as the solid surfaces. The selectivity of this method, as well as matrix and optical effects of relevance have been studied and discussed. 95% Conf idence limits of detection are 0.1-0.3 nmol and calibration is linear up to 4 nmol. Analysis of the two pesticides in mixtures was carried out based o n mathematical treatment peaks whose wavelength of maximum intensity depend s on the composition of the mixture. (C)2000 Elsevier Science B.V. All righ ts reserved.