Simultaneous determination of organophosphorous insecticides in bean samples by gas chromatography - flame photometric detection

The indiscriminate use of organophosphorous pesticides (OPPs) in crops may leave residues in food and may cause poisoning in the applicators. A method was developed for the determination of five OPPs in bean samples by Gas Chromatography-Flame Photometric Detection (GC-FPD). Validation parameters comprised linearity between 0.24 and 8.56 mu g g(-1) (r = 0.9985) for diazinon; 0.23 and 8.14 mu g g(-1) (r = 0.9959) for methyl parathion; 0.28 and 10.25 mu g g(-1) (r = 0.9987) for methyl pirimiphos; 0.52 and 18.87 mu g g(-1) (r = 0.9955) for malathion; 0.86 and 13.67 mu g g(-1) (r = 0.9919) for ethion. The limits of quantification (equal to those of detection) were the lowest rates of ranges mentioned above for each compound. The extraction method showed approximately 95% recovery, with CV% < 15%. Although twenty-eight bean samples obtained in the southern region of the state of Minas Gerais, Brazil, were analyzed, they failed to match any of the OPPs under analysis. The absence of OPPs in the samples could be due to the degradation that occurred between the use of OPPs and bean commercialization, levels below the detection /quantification limits and the non-use of OPPs in bean cultivation.