Research On Antibiotic Residues In Cultured Shrimp, Penaeus Chinensis

The presence of antibiotic residues in aquatic products has become a matter of considerable debate in food safety. Chloramphenicol (CAP),sulphamethoxazole_<sub>SMZ and oxytetracycline (OTC) in shrimp, Penaeuschinensis were researched.Detection of 3 antibiotics by HPLC was assayed. Determination of chloramphenicol and sulphamethoxazole by HPLC was mature and adopted. Determination of oxytetracycline was not suitable for aquatic products. GB/T14931-1994 "Method for determination of tetracyclines (TCs) residues in meat" was improved to be suitable for shrimp. TCs residues in shrimp were extracted by Solid Phase Extraction (SPE). The extracted TCs were detected on HPLC. The optimum HPLC parameters were acquired. Wavelength: 355nm; Column temperature: 35℃; Flowing rate: 1.0ml/min; Mobile phase:CH3CN/0.01mol/LNaH2PO4, v/v= 23/77, pH 2.0-2.5. The correlative coefficients of OTC was 0.99998 ranged from 0.1 to 10μg/ml. The average recovery of OTC in shrimp spiked at 2 levels of 0.075 and 0.1 were 75%. The detection limits of the method were 0.05mg/kg.Muscle residue depletion of chloramphenicol, sulphamethoxazole and oxytetracycline following oral administration was evaluated in shrimp, Penaeus chinensis under field conditions. Three groups of shrimps were cultured in tanks filled with seawater and fed a commercial medicated diet containing 2000 mg kg-1 CAP, SMZ and OTC, respectively, twice daily for 3 days. Sampling was conducted at different intervals (0, 0.5, 1, 1.5, 2, 3, 4, 8, 10, 12, 16, 24, 36, 48, 72, 96, 120, 144, 168h) after the cessation of medication. Drug analysis was carried out by HPLC. The elimination half-life (t1/2) of CAP was 10.04h, the elimination half-life (t1/2) of SMZ was 5.68h and that of OTC was 16.12h. If the EU MRPL value of 0.3ng/gfor CAP and MRL value of 0.1 μ g/g for SMZ and OTC quoted for muscle from finfish is extended to shrimp muscle, extrapolation of the data indicates that it would be passed after a 139.7h (95%CI=132.0-144.4h), 30.6h (95%CI=27.2-33.1h), 90.3h (95%CI=87.9-92.5h) withdrawal period for CAP, SMZ and OTC in shrimp muscle, respectively.This paper presents the net change by cooking on residues of chloramphenicol(CAP), sulphamethoxazole(SMZ) andoxytetracycline(OTC) in shrimp muscle balls. Three groups of shrimps were cultured in tanks filled with seawater and fed a commercial medicated diet containing 2000 mg kg-1 CAP, SMZ and OTC, respectively, twice daily for 3 days. Muscle was ground, mixed and formed into 5g "meatballs". These antibiotics were determined by high-performance liquid chromatograph. By using the usual cooking methods, steaming, boiling, oil frying, roasting and microwaving, the meatballs containing these antibiotics were treated for the specified times. Net residues in the shrimp meatballs cooked by steaming were reduced 53 % - 91% in 9 min. Net residues in the shrimp meatballs cooked by boiling were reduced 75 %⁹6% in 9 min. In roasting cooking, the CAP, SMZ and OTC residues were reduced 63%⁸8% in 9 min. In oil frying cooking, the CAP, SMZ and OTC residues were reduced 65 % - 94% in 9 min. By the micro-waving cooking, three antibiotic residues were reduced 66% ⁸9% in 1 min. Reducing half-lives of antibiotics in shrimp muscles cooked were estimated as follows: 8.7min for CAP, 15.51min for SMZ and 14.15min for OTC in steaming; 5.1 min for CAP, 10.31 min for SMZ and 6.46min for OTC in boiling; 9.28min for CAP, 3.86min for SMZ and 8.53min for OTC in oil frying; 6.08min for CAP, 7.50min for SMZ and 8.53min for OTC in roasting; 0.86min for CAP, 0.88min for SMZ and 0.76min for OTC in micro-waving.MTT assay was used to determine the cytotoxicity of gentamicin inhuman hepatocytes. The result (IC50>10.0) showed that the cytotoxicity to human hepatocytes was not significant.