Application of Bi-Column Gas Chromatography and Gas Chromatograpy in Hyphenation with Mass Spectrometry to the Detection of Residual Pesticides in Vegetables

In the detection of various residual pesticides in different kinds of vegetables,serious interferences due to the vegetable matrix were encountered frequently.A simple pretreatment of vegetable samples by extraction with acetonitrile was adopted in order to avoid loss of pesticides.Organo-phosphorus pesticides were determined in an aliquot of the extract by GC with FPD,and organochlorine pecticides as well as pyrethroids by GC with ECD.Two chromatographic columns with different polarity were used in GC-analysis to obtain a better separation of the interfering substances from the objective pesticides.Even then,pseudo results were sometimes obtained.As a further measure,GC-MS was applied to clear the obscurity.By the proposed method,the accuracy and reliability of the detection of residual pesticides were greatly increased.