Determination of Ethopabate by Gas Liquid Chromatography

A procedure for the gas chromatographic determination of Ethopabate (ETP) in chicken tissues and eggs was established as follows. A mixture of 0.5ml of benzene solution of ETP, 70μl of heptafluorobutyric acid (HFB) and 200μl of heptafluorobutyric anhydride (HFBA) was allowed to stand for 15min in a paraffin bath at 220°C. The reaction product was extracted with benzene in alkaline sodium carbonate. The ETP was determined by gas liquid chromatography.Gas chromatography: A Shimadzu GC 4CMPFE gas chromatograph with an ECD was used for determination of ETP. The column consisted of a glass tube (1m×3mm ID) packed with 5% Thermon 1000 on Chromosorb W (AW, DMCS 80-100 mesh) and conditioned at 190°C. The detector and injector temperatures were 230°C and the flow rate of nitrogen carrier gas was 40ml/min.The recoveries of ETP added to chicken tissues and eggs were in the range from 90.8 to 96.3 with an average of 94.3% at levels from 0.1ppm to 0.5ppm. The minimum detectable amount was 10pg as ETP and 0.02ppm in a sample. The calibration curve was linear from 0.02ppm to 0.2ppm.