| Quinolones are a kind of synthesis antibiotic-agents which are widely used in veterinary clinical treatment because of their broad-spectrum bactericidal performance,convenient method of application,low price and so on.Howere,recent years,with the increase of application to the QNs, some bad phenomena such as abuse, or do not obey the withdrawal time are becoming more and more,which have been bringing some serious problems on QNs residues.Ministry of Agriculture has set the maximum residue limit to some of the QNs in food of animal origin.This paper developed a multi-residue method for the confirmation and quantitation of 25 kinds of quinolones(including antofloxacin,balofloxacin,ciprofloxacin,cinoxacin, danofloxacin, difloxacin, enoxacin, enrofloxacin, fleroxacin, flumequine, gatifloxacin, lomefloxacin, marbofloxacin, moxifloxacin, nalidixic, nadifloxacin, norfloxacin, ofloxacin, oxolinic acid,orbifloxacin, pipemidic acid, pazufloxaxin, pefloxacin, sarafloxacin,sparfloxacin) in edible tissues of bovine(including liver,kidney, muscel,fat tissue and milk) with LC-MS/MS for perfecting the multi-residue detection methods of QNs.The samples were extracted twice by 1% formic acid in acetonitrile-methanol(95:5,V/V) solution,then the supernatant which was extraceted twice was complicated with a constant volume,moving 2 m L from the all extraction solution,and then,this part of extraction solution was defatted by n-hexane which has been saturated by acetonitrile. The n-hexane was apartmented and abandoned, the eluent reduced was concentrated to dryness under a stream of nitrogen.Then the residue was dissolved in water with 0.1% formic acid-methanol(95:5,V/V).Twice high-speed centrifuge to remove impurities, following filtrated by 0.22 μm filterable membrane.The analytes were separated through Luna C18 chromatographic column with the mobile phase of 0.1% fomic acidmethanol system under a gradient elution program and analyzed by LC-MS/MS.Under this method,the result showed a good linear relationship between the peak area and the concentration of 25 kinds of quinolones drugs during their linear ranges with correlation coefficient more than 0.99. At the same time adding experiment on high, medium and low levels, the recovery rate of 25 kinds of QNs drugs in various tissues were between 62.7%~116.0%, except ANT which got a relative low recovery rate in kidney and muscle(respectively were 51.9%~71.7% and 56.2%~68.3%).The intra-assay coefficient of variation between 0.1%~14.4%, inter-assay coefficients of variation between 1.0%~16.0%, consistent with the requirements of trace analysis.The limit of detection(LOD) and the limit of quantification(LOQ) of the 25 quinolones in bovine respectively were:the LOD and LOQ in the muscle, liver and kidney tissues were similarly 0.2~1.0 μg/kg and 0.5~2.0 μg/kg; the LOD and LOQ in fat tissue were 0.1~1.0 μg/kg and 0.5~2.0 μg/kg;and the LOD and LOQ in milk were 0.1~1.0 μg/kg and 0.2~2.0 μg/kg.The results showed that the LC-MS/MS determination methods described in this invstigation was demonstrated good reproducibility, high sensitivity and specificity, while totally match the analysis on residus of QNs in edible animal tissues. |
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