| The unique breed of black-bone chicken originated from Taihe black-bone chicken in China,which was rich in melanin and differented from other chicken breeds and had medicinal nourishing effect and was the main raw material for preparing Wuji Baifeng Pills.Therefore,it was popular among the people.Enrofloxacin and ciprofloxacin were commonly used in animals,which were important drugs for prevention and treatment of respiratory and intestinal diseases in poultry.The laboratory found that the metabolism and elimination of enrofloxacin and ciprofloxacin in black-bone chickens were significantly different from other chicken breeds.In this paper,the residues of enrofloxacin and ciprofloxacin in black-bone chicken tissues and plasma were determined by High performance liquid chromatography(FLD).The mobile phase was 0.05 mol/L phosphoric acid-triethylamine buffer solution: acetonitrile=85:15(v/v).Excitation wavelength and emission wavelength of Fluorescence detector was 280 nm and 450 nm,respectively.The acetonitrile-water(acetonitrile:water=7:3,v/v)containing 0.1% lactic acid was used as the extract.Spiked samples of low,medium and high concentration were prepared by adding enrofloxacin and ciprofloxacin to blank tissues and plasma of black-bone chicken.The results showed that recovery rate of enrofloxacin in spiked samples of muscle,skin+fat,kidney and liver of black-bone chicken was 84.1%～98.2%,and the recovery rate of spiked plasma was 95.3%～105.9%.RSD was less than 4.4%.The recovery rate of ciprofloxacin in spiked sample of black-bone chicken tissues was 81.8%～94.3%,and the recovery rate of spiked plasma was 99.1～108.0%.The RSD was within 6.2%.The method had the advantages of good extraction effect,simple pretreatment and high detection sensitivity,which could achieved the detection of enrofloxacin and ciprofloxacin in black-bone chicken tissues.The black-bone chicken after treatment of ciprofloxacin 80 mg/L for 3 consecutive days,at 4 h(0 withdrawal period)after withdrawal,the average concentration of ciprofloxacin in the skin+fat,muscle,kidney,liver,gizzard and lung of black-bone chickens decreased slowly from 1547.6,288.2,485.4,889.9,426.5 and 553.3 μg/kg.at 28 d after withdrawal,ciprofloxacin was not detected in the lungs.at 49 d after withdrawal,the average concentration of ciprofloxacin in skin+fat,muscle,kidney and gizzard 113.4,16.2,37.3 and 55.8 μg/kg,respectively,and ciprofloxacin was not detected in the liver.The ciprofloxacin concentration in plasma was extremely low,which was 13.3 μg/L at 4 h,and was not detected at 1 d after withdrawal.The results showed that ciprofloxacin excreted slowly in black-bone chicken and the main residual target tissue of the ciprofloxacin was skin+fat.The black-bone chicken after treatment of enrofloxacin 75 mg/L for 5 consecutive days.The results showed that the residue of enrofloxacin in black-bone chicken was much higher than ciprofloxacin.From 4 h(0 withdrawal time)to 49 d after withdrawal,the average concentration of enrofloxacin+ciprofloxacin in the skin+fat,muscle,kidney,liver,lung and gizzard of black-bone chickens decreased slowly from 45575.4,8158.5,7868.3,1699.6,7706.9 and 30348.7 μg/kg to 3618.9,683.0,880.6,147.8,4198.3 and 663.6 μg/kg,respectively.Whereas residual marker in plasma was only 158.3 μg/L at 4 h,which was not detected at 42 d after withdrawal.The research showed that enrofloxacin had severe residue in black-bone chicken and slow elimination.Enrofloxacin could be metabolized into ciprofloxacin in black-bone chicken,and mainly existed in tissues and plasma as original.Referring to the maximum residue limit of enrofloxacin+ciprofloxacin in edible poultry tissues,in order to ensure the safe usage of ciprofloxacin or enrofloxacin in black-bone chickens,the residual data were analyzed with WT1.4 software at 95 % confidence interval.The results suggested that the withdrawal time of ciprofloxacin and enrofloxacin should be 75 days and 134 days respectively after administration of the above-mentioned dosage. |
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