| In this study, the methods of high-performance liquid chromatography (HPLC) have beendeveloped for detection of chlorteracycline in different tissue (muscle, liver, kidney) in chicken andchicken feces. In order to determine withdraw time in chicken, we determined the residues ofchlorteracycline in different tissues of chicken at different time. The degradation characteristics have alsobeen researched under different environment conditions in chicken feces.The methods of HPLC have been developed detection of chlortetracycline in multi-tissues ofchicken, which is used widely in feed additive. The extraction process as followed: tissue was extractedwith MCI-Vain-Na2EDT. Liquid chromatographic analyses were performed by isocratic elution using amobile phase: acetonitrile: methanol: water, 16:8:76 (V/V). Detection wavelength set at 370nm. Columnwas used Shimadzu VP-ODS C18. The column was set at 35℃, and flow rate was 1ml/min.The recoveries of chlortetracycline (0.01μg/mL,0.10μg/mL,0.20μg/mL,0.40μg/mL,2.00μg/mL) in muscle, liver and kidney were 92％～101％;:88％～04％; 79％～86％, respectively. Thecoefficients of variation within batches were≤8％, The coefficients of variation between batches were≤10％, The linear scope was 0.01-2.00μg/mL. The limits of detections in muscle, liver and kidney were20 ng/mL,40 ng/mL,50 ng/mL, respectively. The results indicated that the method for thechlorteracycline in chicken was simple, specific, accurate and sensitive.A total of 48 Xiang hang Chickens (40 days) were randomly divided into test and control group.Test group were feed contained chlorteracycline powder for 12 days. Chickens were slaughtered at 2, 4,7, 9, 12, 16, 23 and 28 day of (test and control group was 4 and 2, respectively). The weights of muscle,liver and kidney were accurately weighed and the residual concentrations of chlorteracyclinein weredetected using HPLC. The results suggested that the residual concentration in muscle at 9 day was belowthe maximum residue limits (0.10ug/g). However, the withdraw time was higher than the regulation (7day) by the office of National Feed Industrial. The residual concentrations in liver and kidney ofchlortetracycline were lower than the maximum residue limits (0.30ug/g, 0.60ug/g) at 23, 28 day,respectively.The fresh chicken feces were obtained from different age 18 healthy chicken, and were not detectedchlortetracycline. The mixture standard solution of CTC and OTC was added in fresh chicken feces at the concentration of 0.5, 1.0 and 4.0ug/ml respectively. The chicken feces were divided to two groups,one were put in the incubator under photophobic condition; another were under the natural illumination.Samples were collected after 0, 0.5, 1, 2, 3, 5, 7, 9, 12 and 15 days, The concentration of chicken feceswas determined by HPLC. According to the theory of degradation kinetics, we fitted the changed trendof concentrations in chicken feces under different time and studied the degradation characteristics ofchlortetracycline in chicken feces.We found that CTC in chicken feces were nearly seldom degraded in photophobic condition.After 15 days, the degradntion rate of CTC at three different concentrations was 5.93％, 7.36％, 6.20％,respectively. But under the natural illumination, the degradation of CTC in chicken feces was very fast.After 15 days, the degradation rate of CTC at three different concentrations was 98.62％, 89.53％,95.98％, respectively. The degradation processes of CTC in chicken feces was consisted with the firstorder kinetic equation as Ct=C0e-kt. Calculated by this equation, the variation of half-life (3.24±1.02)din chicken feces was not significant,...
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