Study On Residual Determination And Elimination Of Chloramphenicol In Chicken Tissues

Meta-nitrochloramphenicol (m-CAP) is a kind of internal standards used in gas chromatography for chloramphenicol (CAP) residue detection. It is an effective method for increasing accuracy of quantitativeness in trace analysis by using m-CAP as an internal standard in Chloramphenicol residue analysis. m-CAP was prepared successfully in this study.In this paper a method was developed for determination of Chloramphenicol by gas chromatography and confirmation of Chloramphenicol by gas chromatography/mass spectrometry in broiler chicken muscles and livers.The tissues was extracted with ethyl acetate .The sample was defatted with hexane and extracted with ethyl acetate, then m-CAP was added to the sample, evaporated to dryness with nitrogen gas.Residue must be dry before adding Sylon N,O-Bis(trimethylsily) trifluoroacetamide (BFT).Added Sylon BFT.After derivatization, tolune and water were added directly to the sample .The organic layer was carefully removed.3ul analytes were determined by GC with micro electron capture detector(uECD) and 1ul confirmed by gas chromatography/ mass spectrometry. Analyzed by negative ion chemical ionization (NICIMS) with selected ion monitored.The ions with m/z 468,466,360,358,322,and 304 were monitor.The recoveries of analytes at the fortified level of 0.1ug. kg -1,1ug. kg-1,20 ug. kg-1 range from 82.8%~94.4% in the muscle , and at the fortified level of 0.2ug. kg-1, 1ug. kg-1,20 ug. kg-1 range from 69.1%-83.5% in the liver,respectively.Coefficents of variation for distribution,CVd,ranged from 2.0% to 4.5% in muscle, from 3.2% to 8.2% in liver,respectively.And for precision CVr,ranged from 2.1% to 12.7% in muscle,from 2.7% to 8.0% in liver,respectively.The limit of detection(LOD) is 0.04 ug. kg-1 in muscle, 0.12 u g. kg-1 in liver.In feeding trial,eighty chicken was divided into 3 groups,high dosage group(800 mg. kg-1 feed),low dosage group(200 mg. kg-1 feed) and blank group,medicated 5 days continually.After the drug withdrawal, the concentrations of the Chloramphenicol residue in muscle and in liver were detected by GC.Fortified low dosage group,the Chloramphenicol residues were 10. 7ug. kg-1 and 2. 65ug. kg-1 at 0,12 hours.at the 8 days,below the LOD in muscle, the Chloramphenicol residues were 0. 73ug. kg-1 at 0 hours, at 12 hours, below the LOD in liver.Fortified high dosage group.the Chloramphenicol residues were 42. lug. kg-1, at the 14 days,below the LOD in muscle. The Chloramphenicol residues were 7. 22ug. kg-1 at 0 hours, at 24 hours, below the LOD in liver.