柱萃取法测定农作物中的残留农药和土样中的二恶英

Column Extraction for the Determination of Multi-residual Pesticides in Crops and Dixoins in soils

经均质的固体样品，根据含水量的不同和被测定组分的差异，分别与硅藻土、硫酸钠、弗罗里硅土等吸附剂混匀成可流动的粉末，装填成柱，然后以不同极性溶剂淋洗。多数情况下，所得溶液不需要进一步净化即可进行色谱分析．用极性溶剂如乙酸乙酯淋洗，选用任一种分散剂均能有效测定作物中的农药残留．在最佳条件下，一些有机磷、有机氯、氨基甲酸酯、拟除虫菊酯农药在某些粮谷、水果和蔬菜中以及多氯二苯并二恶英（ＰＣＤＤｓ）在土样中的添加回收率均大于８０％．实践证明该方法具有省时、省试剂、省净化程序等优点．

Homogenized samples of crops with different content of water were mixed respectively with Celit-545,anhydrous sodium sulfate,florisil and silica gel to form free-flowing powder samples. Each powdered sample was packed in a column and eluted with solvents of differend polarity. Most eluates could be analyzed chromatographically without further cleanup.Any one of the chosen dispersion agent oould be used for the determination of pesticide residues in crops if polar solvent such as ethyl acetate is utilized in elution.Rereveries of carbamaus,pyrethroid and organophosphorous and organochloro pesticides from some grains,vegetables and fruits and PCDDs from soils were higher than 80%.It has been proven both theoretically and practically that the column extraction method saves time and reagents and simplifies the cleanup proceure.