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目的:建立一种基于离子液体的分散液相微萃取的样品前处理技术,结合高效液相色谱方法,测定液态奶中残留药物恩诺沙星和环丙沙星。方法:考察了萃取剂种类、萃取剂体积、涡旋萃取时间、盐浓度、pH因素对萃取效率的影响。确定了最佳萃取条件:以100μL 1-辛基-3-甲基咪唑六氟磷酸盐[(OMIM)PF_6]为萃取剂,氯化钠质量分数为6%,pH=3.2,涡旋震荡3 min,室温下10 000r·min~(-1)离心3 min,取20μL萃取液供高效液相色谱分析。结果:恩诺沙星和环丙沙星质量浓度在5~100μg~L~(-1)范围内与相应的峰面积呈良好的线性关系,相关系数分别为0.999 6和0.999 1;在5~20μg·L~(-1)的添加水平下,平均回收率为83.9%~98.8%,日内RSD均低于7.6%(n=6),日间RSD均低于12.1%(n=3),恩诺沙星和环丙沙星在液态奶中的检出限为0.56μg·L~(-1)和0.97μg·L~(-1),定量限为1.87μg·L~(-1)和3.23μg·L~(-1),市售液态奶样品中均未检出恩诺沙星和环丙沙星。结论:该方法操作简单,消耗试剂少,定量准确,可用于液态奶中喹诺酮类药物残留的分析检测。
OBJECTIVE: To establish a sample pretreatment technique based on ionic liquid for liquid-phase microextraction and to determine residual drugs enrofloxacin and ciprofloxacin in liquid milk by high performance liquid chromatography. Methods: The effects of extractant type, extractant volume, vortex extraction time, salt concentration and pH on extraction efficiency were investigated. The optimal extraction conditions were as follows: 100μL 1-octyl-3-methylimidazolium hexafluorophosphate [(OMIM) PF_6] was used as extracting agent, the mass fraction of sodium chloride was 6%, pH = 3.2, min, centrifuged at 10 000 r · min -1 at room temperature for 3 min, and 20 μL extracts were extracted for HPLC analysis. Results: The concentration of enrofloxacin and ciprofloxacin showed a good linear relationship with the corresponding peak area in the range of 5 ~ 100μg ~ L -1 with correlation coefficients of 0.999 6 and 0.999 1, respectively. The average recovery was 83.9% ~ 98.8% at 20μg · L -1 level with RSD less than 7.6% (n = 6) and daytime RSD less than 12.1% (n = 3) The detection limits of enrofloxacin and ciprofloxacin in liquid milk were 0.56μg · L -1 and 0.97μg · L -1, and the limit of quantification was 1.87μg · L -1. And 3.23 μg · L -1, no enrofloxacin and ciprofloxacin were detected in the commercial liquid milk samples. Conclusion: The method is easy to operate, consumes less reagent and has accurate quantitation. It can be used for the analysis and detection of quinolone residues in liquid milk.