Trace analysis of chloramphenicol residues in egg powders by capillary gas chromatography-electron capture detection

Chloramphenicol (CAP) in egg powder samples was extracted with acetonitrile by sonication. After centrifugation, the supernatant was diluted with water and defatted with n-hexane, and cleanup was performed on a microcolumn of graphitized carbon black (GCB). Different silylation methods were compared for the derivatization of the analytes. Trimethylsilyl N,N-dimethylcarbamate produced stable di-TMS derivatives which were analyzed by capillary gas chromatography-electron capture detection (CGC-ECD) after splitless injection. The meta isomer of the chloramphenicol served as the internal standard for quantitation, and 80% + mean recovery was obtained in the 0.1-10 micrograms/kg (ppb) concentration range.