进样溶剂极性对地下水中有机氯农药色谱行为的影响

Effect of Polarity of the Injection Solvents on the Gas Chromatographic Behaviors of Organochlorine Pesticides in Groundwater Samples

地下水中有机氯农药分析时采用正己烷为进样溶剂,而考核样品的溶剂通常为甲醇。正己烷和甲醇分别是典型的非极性溶剂和极性溶剂。文章研究了正己烷和甲醇两种溶剂对地下水中9种必测有机氯农药(六氯苯、α-六六六、β-六六六、γ-六六六、δ-六六六、p,p′-DDE、p,p′-DDD、o,p′-DDT、p,p′-DDT)色谱行为的影响。结果表明,溶剂的极性对有机氯农药的响应值有显著的影响:甲醇为进样溶剂时,由于极性强,造成汽化室内活性位点的暴露,导致某些待测组分被活性位点吸附,甲醇相的待测物响应值明显低于正己烷相待测物响应值。

This paper presents a study on the effect of the polarity of injection solvents （n-hexane-a typical non-polar solvent and methanol-a typical polar solvent） on the gas chromatographic behaviors in determination of nine organochlorine pesticides （hexachlorobenzene, α-HCH, β-HCH, γ-HCH, δ-HCH, p,p′-DDE, p,p′- DDD, o,p′-DDT, p,p′-DDT）. The results show that the polarity of the injection solvents has obvious effect on the gas chromatographic responses in the determination of organochlorine pesticides. Compared with n-hexane, methanol is strong polar solvent and results in the exposure of the active spits in gasification chamber and losses of some analytes due to the adsorption of the pesticides by the active spits. In order to increase the response of the pesticides in methanol, one of the approaches is increasing the concentration of dimethyldichlorosilane solution used in treating the gasification chamber.