Identification and residue determination of the synthetic antibacterial clopidol in commercial chicken tissues

Residues of the coccidiostat clopidol (3, 5-dichloro-2, 6-dimethyl-4-pyridinol) in commercial chicken tissues were investigated in Sapporo city by means of ECD-gas chromatography. The tissues were extracted with methanol and the extracts were filtered and cleaned up on alumina and anion exchange resin columns. The eluates were treated with diazomethane to obtain the methyl ether of clopidol, which was detected by ECD-gas chromatography. The compounds were detected in commercial chicken tissues at levels of 0.04 to 1.9ppm in 12 out of 31 samples. The detected substance was identified as methyl-clopidol (3, 5-dichloro-4-methoxy-2, 6-lutidine) by mass chromatography. Further studies seem desirable on residual clopidol in livestock products.