Studies On Residues Of Tildipirosin Injection In Pigs

Tildipirosin(TIP),a new kind of semi-synthetic antimicrobial drugs,belongs to the family of Macrolides.It could markedly protect against the pathogene of respiratory disease,including Mannheimia haemolytica,Actinobacillus pleuropneumoniae,Haemophilus parasuis,Pasteurella multocida,Bordetella bronchiseptica,and Histophilus somni.So far,TIP is a new veterinary drug for respiratory diseases,which has not been listed in the Chinese drugs market.The purpose of this study was to develop a new establishment of method for detecting residues of Tildipirosin injection in pigs.To detect Tildipirosin,we utilized API 4000 Qtrap LC-MS-MS instrument,and employed ESI ion source,positive ion scan,ion spray voltage:5.5 kV,TEM:600 ?,the pressure of CUR:20 psi,the pressure of GAS1 and GAS2:35 psi and 40 psi,the pressure of collision CAD:9 psi.Tildipirosin and interial label were used for the quantitative ion,(735.4/98.2,m/z)and(295.050/267,m/z),respectively.In addition,our studies used chromatographic column Synergi Polar-RP(2.5?m,2×50 mm)S/N:H15-010633,selected A acetonitrile-0.1%formic acid in water and B acetonitrile-0.2%formic acid in water as mobile phase,including gradient elution with 0.001 min(95:5),0.80 min(95:5),1.50 min(5:95),3.50 min(5:95),3.51 min(95:5),5.00 min(95:5).Moreover,we set a rate of 0.400 mL/min as the flow rate,the sample injector smooth lotion as acetonitrile,the injection volume as 10 ?L,and the temperature of the sample injector at 4 ?.Then,to treat adequate amount of sample tissues,we firstly measured a few of sample tissues to homogenize took the 2 mL of homogenized samples and added the 2 mL of water to homogenize again.Secondly,the 400 ?L of methanol/acetonitrile precipitant(with 50 ng/mL internal standard solution)was added to the homogenate samples,following by subjecting to a vortex for 5 min to centrifuge at 4000 rpm/min for 10 min and to intake the 200 ?L of supernatant.The TIP of five groups with a rang from the 5.00 ng/mL to 500 ng/mL concentration,which exhibited a good linear relationship,was the correlation coefficient of association(R2)at 0.998,the LOQ at 5 ng/mL,and the average recovery over 90%.Furthermore,searching the stability of Tildipirosin included these stabilities of the samples at room temperature and 70 ?after freeze-thaw,the samples processed after automatic injector temperature(4 ?),the samples treated at room temperature,and the working liquid placed at room temperature,which conformed to the requirements of analysis in biological samples.The experimental methods exhibited an advantage of simple and high sensitivity for detecting the new drug of Tildipirosin in the tissues of animal.In this study,we established a well method to examine the residues of Tildipirosin in pigs.Our results showed that these tissues of fat and muscle were the less than the minimum quantitative limit at 15 th day.In addition,the levels of tissues of lung and kidney were the 47.2 ng/mL and 81.25 ng/mL,respectively,and a higher concentration in the liver tissues at 15th day.