Study On Residues Of Lincomycin And Gentamicin Injection Medicine In Swine By UPLC/MS/MS

Lincomycin and gentamicin injection has been developed by ourselves.Lincomycin is one of the agent of Lincosamide antibiotics, it has highly antibiotic against gram-positive bacteria and gram-negative bacteria. The Janpan Positive list system has established a maximum residue limit (MRL) of 0.1mg/kg for Lincomycin in porcine edible tissues (heart, liver, lung, kidney, muscle and fat).Gentamincin is one of the agent of Aminoglycoside antibiotics, it has a high activity against Staphylococcus.The Janpan Positive list system and China Ministry of Agriculture have established a MRL of 0.1mg/kg for Gentamicin in porcine edible tissues.In order to keep this compound injection used standardly in hogpen, keep human body health, develop animal husbandry and promote the product import, it is necessary to establish residue monitoring system and withdrawl time.A ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-MS/MS) for determination of Lincomycin and Gentamicin residues in swine edible tissues has been developed. Tissues are extracted with 20mM heptafluorobutyric acid, purification by C18SPE cartridge. The UPLC separation was performed on an ACQUITY UPLC^TM BEH C₁₈ column (2.1 mm×100 mm, 1.7μm) utilizing a gradient elution program of acetonitrile and water (containing heptafluorobutyric acid) as the mobile phase.confirmation and quantification by mass spectrum in the multiple reaction monitoring(MRM)mode via positive electrospray ionization(+ESI). The linear ranges of 2 type of drugs are between 0.01 mg/kg～2 mg/kg,and the linear correlation coefficient above 0.99. The recoveries of lincomycin and gentamicin at the different spiked concentration levels ranged from76%～89.4%,with RSD of 8.1%～11.4%.The detection limit of lincomycin and gentamicin are 0.005mg/kg and 0.018mg/kg.In order to study the depletion lincomycin and gentamicin compound injection residues in the porcine tissues, the compound injectiong medicine was injecting to 32 pigs at 3.5ml/kg dose. Animals were killed at 4, 10, 20, 30, 40, 50, and 60 days of withdrawal after the last injection.The results indicated that concentrations of lincomycin and gentamicin residue were 0.098mg/kg and 490mg/kg in kidney,0.03mg/kg and 22.7mg/kg in liver,0.006 mg/kg and 1.1mg/kg in muscle,0.008mg/kg and 2.17mg/kg in heart,0.115mg/kg and 7.2mg/kg in lung after withdrawal for 4d. The concentrations of drugs tartrate residue are lower th an MRLs of Japanese Positive list and China Ministry of Agriculture; According to the WT1.4 software methods of calculation for the withdrawal time, the withdrawal time for this compound injection medicine was advised as 76d in pig.