Sample pretreatment for determination of chlorinated organic pollutants in plants by gas chromatography and gas chromatography-mass spectrometry

The sample pretreatment methods for the determination of chlorinated organic pollutants in plants by gas chromatography (GC ) and GC-mass spectrometry (MS) were established. The homogeneous extraction was used to extract the chlorinated organic pollutants from plants. The main interferences in the co-extract from several kinds of plant samples were recognized. The sensitivity of the analysis on organochlorine pesticides and polychlorinated biphenyls (PCB) in plant samples was effectively improved. The removal efficiency of the interferences from the extract by gel permeation chromatography (GPC) and solid-phase extraction (SPE) was investigated. The impurities such as fatty acids and phenols can be cleaned-up through a Carb/NH2, SPE column with 20 mL mixed solvent of hexane-ethyl acetate (8:2, v/v) in 3% toluene as the eluent, and the recoveries were higher than 74%. It was necessary to combine GPC with SPE as the clean-up method when the sample was determined by GC, and only the SPE as the clean-up method was used if a mass spectrometer was employed as a detector. The methods are rapid and sensitive, and can be used in the analysis of organic pollutant residues in plant samples efficiently.