Determination of organochlorine pesticides in plants by stir bar sorptive extraction coupled with gas chromatography

Organchlorine pesticides in buckwheat and sophora flavescens were determined using stir bar sorptive extraction coupled to gas chromatography and electron capture detection. Poly (phthalazine ether sulfone ketone (PPESK) and poly(dimethysiloxane) (PDMS) were used as extraction phases, and their relative extraction amount for 8 organochlorines were compared. The results showed that the extraction capacity of PPESK were 1 to 11 times higher than that of PDMS. Factors affecting the amount of extraction, such as temperature, extraction time and ion strength, were optimized, and the matrix effect was also evaluated. Limits of detection (LOD) of organchlorines in buckwheat were between 4 pg/g and 85 pg/g; the error of precision was less than 26%; the recoveries were from 83% to 135%. The LOD of organchlorines in sophora flavescens were in the range of 3 - 17 pg/g, the error of precision was less than 17%, the recoveries were 82% -128%.