Pesticide residues in fruits and vegetables: High-order calibration based on spectrofluorimetric/pH data

Abstract

The aim of the present work was to quantify simultaneously four pesticides, thiabendazole, fuberidazole, carbaryl and naphthyl acetic acid, in vegetables and fruits, measuring excitation–emission fluorescence matrices in a flow injection system with double pH–gradient. The generated third–order data were processed by applying multivariate calibration procedure unfolded partial least squares coupled to residual trilinearization (U–PLS/RTL), permitting overcome the severe spectra overlapping among the analytes and also with the background of real samples. The vegetable tissues were fortified at concentration levels taking into account the maximum residue level, acquiring good recoveries for all analytes, with values between 80 and 115%. The developed method enabled determining the analytes in complex samples (lettuce, pear, orange and mushroom) with a simple extraction step with ethyl acetate, in an appropriate analysis time and without sophisticated instruments.