| With the development of stock raising, all kind of antibiotics had been used as veterinary drug, for example penicillins, tetracyclines, aminoglycosides, sulfonamides and chloramphenicols. They are used for the treatment of bacterial diseases and promotion of growth. The residues of veterinary drug had been appeared in animal derived food as the illogicality application of veterinary drug. As we entered the world trade organization, all countries and union have strictly control the residues in imports and exports trade for protecting people health, especially the penicillins, tetracyclines and aminoglycosides, they are widely used and harm for human health. Our country has not any method for determination of multi-residues of penicillins, tetracyclines and aminoglycosides in animal derived food. In order to control the food safety and protect the benefit of our country, we developed three methods to determine the residues in animal derived food based on the experience of our laboratory and literatures.Three High performance liquid chromatographic (HPLC) methods of determination of multi-residues of penicillins, tetracyclines and aminoglycosides in animal derived food have been developed. They applied different sample preparation and determination, for example pre-column derivatized ion-pair HPLC, ion-exchange HPLC with post-column derivatized and fluorometric detection, etc.The first ion-pair HPLC method with solid-phase extraction and pre-column derivatized could determinate seven important penicillins (amoxicillin, penicillin G, ampicillin, penicillin V, oxacillin, nafcillin and dicloxacillin) multi-residues in pig muscle, pig liver, pig kidney, chicken muscle, chicken liver and milk. The residues of penicillins in pig and chicken muscle were extracted with phosphate buffers and directlycleaned up; Those in pig liver, pig kidney and chicken liver were first extracted with acetonitrile followed by phosphate buffers, The solution of acetonitrile was evaporated to dry at 45-50 "C under a stream of nitrogen and redissolved by the second extraction for SPE clean-up. Those in milk were extracted directly with solution of tetrabutylammonium bromide and then evaporated to dry at 45-50 °C under a stream of nitrogen, the residues were redissolved by phosphate buffers for SPE clean-up. All extraction was cleaned up with Accubond SPE, The SPE eluate was acetonitrile, The eluate was evaporated to dry at 45-50 °C under a stream of nitrogen, redissolved with standard dilute solution, derivatized with benzoic anhydride and 1,2,4-triazole mercury (II) reagent. Chromatography was performed by RP-HPLC with ultraviolet detection at 325nm. The limit of quantitation was lOug/kg for standard solution of amoxiciUin, penicillin G, ampicillin and penicillin V, The limit of quantitation were 30ug/kg for standard solution of oxacillin, nafcillin and dicloxacillin. The limit of detection and the limit of quantitation were 2(ag/kg for amoxicillin, penicillin G, ampicillin and penicillin V. those of oxacillin, nafcillin and dicloxacillin were 15ug/kg for milk sample. The limit of detection and the limit of quantitation were 25ug/kg for amoxicillin, penicillin G, ampicillin and penicillin V. those of oxacillin, nafcillin and dicloxacillin were 75(ag/kg for tissue samples. The mean recoveries of spiked penicillins at 2~300ug/kg were 64.4%~88.0% and coefficient of variation were less than 19.4%. The method is suitable for determination of multi-residues of penicillins in pig tissues, chicken tissues and milk.The second HPLC multi-residues method was developed for determination of oxytetracycline, tetracycline, chlortetracycline and doxycycline in pig muscle, pig liver, pig kidney, chicken muscle, chicken liver, chicken egg, fish muscle and milk. The tetracyclines multi-residues were extracted with Mcllvaine buffers from samples and purified using solid-phase extraction, eluted with methanol including oxalic acid. Chromatography was performed by RP-HPLC with ultraviolet detection at 350nm. The limit of quantitation was 25ug/kg for tetracyclines standard solution. The limit of detection and the limit of quantitation were 50ug/kg for tetracyclines in all samples. Recoveries of tetracyclines from spiked samples at the concentration of 50, 100, 200ug/kg were 70.4%~89.9% and coefficient of variation were less than 16.0%. The method is suitable for determination of tetracyclines multi-residues in pig muscle, pig liver, pig kidney, chicken muscle, chicken liver, chicken egg, fish muscle and milk.The third ion-exchange HPLC multi-residues method with post-column derivate andfluorometric detection was developed for determination of kanamycin, ampramycin, neomycin and gentamicin in pork and milk. The aminoglycosides multi-residues were extracted with phosphate buffers from samples, deproteined with TCA solution and purified with solid-phase extraction, eluted with methanol and evaporated to dry at 45-50 °C under a stream of nitrogen. Chromatography was performed by ion-exchange HPLC with post-column derivate and fluorometric detection. The limit of quantitation was 312ug/kg for kanamycin, ampramycin, and gentamicin and 625ug/kg for neomycin standard solution. The limit of detection and the limit of quantitation were lOOug/kg for kanamycin, ampramycin, and gentamicin and 200ug/kg for neomycin in all samples. Recoveries of aminoglycosides from spiked samples at the concentration of 100~800ug/kg were 71.1%~85.4% and coefficient of variation were less than 18.9%. The method is suitable for determination of aminoglycosides multi-residues in pork and milk.Three HPLC methods described in this paper provides a sensitive and reliable procedure for the quantitative analysis of penicillins, tetracyclines and aminoglycosides in animal derived food. The low detection limits and the high selectivity make the methods suitable as confirmation methods in residues analyses. Three methods suit for determination of multi-residues of penicillins, tetracyclines and aminoglycosides in department of the center for veterinary medicine and custom immigration quarantine.
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