[Study on the analytical method for organochlorine pesticide residue using gas chromatography-mass spectrometry]

A gas chromatographic-electron ionization--mass spectrometric method (GC-EIMS) was developed for determining organochlorine pesticide residues. Ten organochlorine pesticides including alpha, beta, gamma and delta isomers of hexachlorocyclohexane(HCH), pp'-DDE, pp'-DDT,op'-DDT,pp'-DDT,pentachloronitrobenzene (Quintozene, PCNB) and hexachlorobenzene(HCB) were determined respectively. Targeted pesticide analyses were separated on DB-5 capillary column. The optimum chromatographic conditions and MS parameter were determined. In test condition, each constituent in the standard mixture was separated efficiently. The retention time of each compound and its characteristic ion were determined in fullscan mode from 50 to 450 amu. The values of their mass spectrum on the total ion current(TIC) with fullscan mode agree with those of NIST and pesticide libraries. The characteristic ions were selected to quantify at m/z 181 for the isomers of HCH, m/z 284 for HCB, m/z 295 for PCNB, m/z 246 for pp'-DDE, m/z 235 for pp'-DDD, op'-DDT and pp'-DDT. The accuracy and reliability were proved respectively by linear test, precise test and recovery test. The linear ranges of PCNB and pp'-DDT are 0.0025-0.50 microgram/ml. The ranges of the isomers of HCH, pp'-DDE, pp'-DDD and op'-DDT are 0.0020-0.40 microgram/ml. The limits of detection are 0.0025 ng for PCNB and pp'-DDE, but 0.0020 ng for the isomers of HCH, HCB, pp'-DDE, pp'-DDD and op'-DDT.