Abstract: A method is described for the determination of endosulfan pesticide residues in Litopenaeus vannamai by capillary gas chromatography. The residues of α-endosulfan and β-endosulfan were extracted from the sample with ethyl acetate, and the extract was cleaned up using a neutral alumina column and an active carbon column after concentrated and then eluted with a mixture of n-hexane-ethyl acetate (1∶1, v/v). During the process of purification, the flow rate of eluent was controlled within 3 mL/min. The eluate was collected and evaporated to 1 mL for analysis. The determination was performed on a gas chromatograph equipped with an electron capture detector. The retention time was used for qualification and the external calibration standard was used for quantitation. The results obtained showed that the recoveries were 80.5%-97.3% for α-endosulfan and 81.1%-109.5% for β-endosulfan. The limit of detection (LOD) was 0.002 mg/kg, and the limit of quantitation (LOQ) was 0.007 mg/kg for both. The precision of the method, expressed as the relative standard deviation for the within-laboratory repeatability, was generally below 8.5%. The method was used for the analysis of Litopenaeus vannamai samples from Guangxi Province, a Litopenaeus vannamai aquiculture area in south China.

Key words: endosulfan, Litopenaeus vannamai , residue, capillary gas chromatography (CGC)