Author(s): S Islam, MS Hossain, N Nahar, M Mosihuzzaman, MIR Mamun
A reverse phase high performance liquid chromatographic method with an acetonitrile-water mobile phase gradient and UV/Visible detection is described for the determination of three pesticides, frequently used in agriculture, in eggplant samples. The samples were sprayed with three pesticides namely, Diazinon, Malathion, Sumithion at three different doses and were harvested at two different Pre-Harvest Interval (PHI) of days 1 and 5 after the application of the pesticides. Sample preparation involved extraction with ethyl acetate and clean up was accomplished by solid-phase extraction using florisil columns. Calibration curves that were constructed for the analytes with matrix matching followed linear relationships with good correlation coefficients (R2>0.990). The average recoveries of the pesticides which were sensitive to matrix effects ranged from 88-120%. Detection limit of less than 0.02 mg kg-1 showed that the method developed can be used to determine the pesticide residues in concentrations lower than the maximum residue limits. In the analysis of residues, samples treated with Diazinon at all doses, residual amounts above Maximum Residue Limit (MRL) (0.02 mg kg-1) were found. Malathion and Sumithion were found above MRL (0.5 mg kg-1) value in only one sample for each pesticide.