Extraction and clean-up method for the determination of twenty organochlorine pesticide residues in tomatoes by GLC-ECD

A method is described for the simultaneous extraction and determination of twenty organochlorine pesticides residues [hexachlorocyclohexane (HCH) isom ers (alpha, beta, gamma, delta), aldrin, dieldrin, endrin, heptachlor and i ts epoxide (HE), hexachlorobenzene (HCB), alpha-endosulfan, o,p'-DDD, p,p'- DDD, o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-DDT, dicofol, methoxychlor, and mir ex] that were spiked in tomatoes. Samples were extracted with ethyl acetate , and the extract was subjected to a rapid clean-up using a Florisil column . The residues were determined by GLC-ECD using two columns of different po larity. The calibration graph correlation coefficient ranged from 0.9903 to 0.9990. The recoveries ranged from 95 to 99% with relative standard deviat ion ranging from 0.5 to 14.7% in the concentration range 0.005 to 0.2 mu g/ g. The limits of detection ranged from 0.004 to 0.05 mu g/g and the limits of quantification ranged from 0.005 to 0.174 mu g/g.