Study On Residues Determination And Residual Elimination Of Doxycycline Hydrochloride Long-Term Injection In Edible Tissue Of Swine

Doxycycline hydrochloride is one kind of tetracycline broad-spectrum antibiotics, whose antimicrobial spectrum is analogous to tetracycline and its antibacterial effect is2-4times stronger than similar drugs’. It is mainly used for rickettsia, mycoplasma, chlamydia and brucellosis treatment. Doxycycline hydrochloride long acting injection is a new kind of controlled release formulations, which has the traits of high efficiency and long efficiency. A fast, sensitive and credible ultra high performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS) method was established to determinate the residues of doxycycline hydrochloride in the edible tissues (muscle, liver, kidney, skin and fat) of pigs and to research the law of its elimination in pigs, which has important significance in theory and practice for developing a simple and credible inspection standard and determining medicine withdrawal time.A UPLC-MS/MS detection method of pigs muscle, liver, kidney, skin and fat was established firstly in this paper. After choosing Mcllvaine-Na2EDTA buffer solution as extraction solvent to extract the determinand in tissues and using a HLB solid-phase extraction cartridge for further clean-up, this study makes analysis in the MS spectra of positive ion mode(ESI+) by using multiple reactions monitoring(MRM). The limit of detection (LOD) and limit of quantitation (LOQ) is5μg/kg and10μg/kg respectively. The recoveries range from75.4%to104.2%when spiked with different levels of analyte, with relative standard deviations generally below12%.This study determines the residues elimination law of doxycycline hydrochloride in pigs by injecting doxycycline hydrochloride long-term injection with the dose of10mg/kg and collecting samples0,7th,14th,21st and28th days after drug withdrawal. The result shows that the drug concentrations in muscle, liver, kidney, skin and fat are all lower than the maximum residue limit40days after drug withdrawal.In conclusion, a rapid, simple, sensitive and reliable UPLC-MS/MS method for the determination of doxycycline in the edible tissues of pigs was developed. The method satisfactory was validated with respect to specificity, sensitivity, accuracy and precision. And, the method is successfully applied to residue depletion study.