Validation and application of a multi-residue method, using accelerated solvent extraction followed by gas...

A multi-residue method was developed to determine different types of pesticides in soils. An extraction with pressure and temperature, through accelerated solvent extraction (dichloromethane:acetone, 50:50, v/v). The pesticides were determined by gas chromatography with several selective detectors: electron capture detector, pulsed flame photometric detector and thermionic specific detector. The following parameters were determined: limit of detection, limit of quantification, equipment linearity (working interval), method linearity as well as, method accuracy and precision. The average recoveries ranged between 76 and 106%, with the exception of chlorothalonil, which had an average recovery of 46%. Additionally, detection limits from 0.9 to 7.6ng g -: (1) and the quantification limits from 3.00 to 25.47ng g -: (1) were estimated. In terms of linearity and precision, the results obtained were in the ranges considered adequate (R(2) ≥ 0.98 and coefficient of variation (CV) ≤ 20%), with the exception of aldrin (R(2) = 0.946, CV = 35.79%), lindane (R(2) = 0.917, CV = 32.91%) and chlorothalonil (R(2) = 0.8184, CV = 81.35%). The proposed method was used to evaluate pesticides in real soil samples, detecting concentrations over 1000ng g -: (1) for some pesticides. The method was correctly validated and provided for the rapid determination of pesticides in soil.