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

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.