浸入式三相液相微萃取-高效液相色谱法对饮料中7种有机酸的同时测定

Simultaneous Determination of Seven Organic Acids in Beverages by High Performance Liquid Chromatography Coupled with Immered Three-phase Liquid-phase Microextraction

建立了一种利用三相液相微萃取（LPME）技术进行样品前处理、高效液相色谱（HPLC）法同时测定饮料中酒石酸、甲酸、乙酸、乳酸、琥珀酸、苹果酸和柠檬酸7种低相对分子质量有机酸的分析方法。考察了萃取溶剂、搅拌速率、盐效应、萃取时间、接收相和给出相pH值等因素对萃取效率的影响。优化后的实验条件：磷酸三丁酯（TBP）为萃取剂,萃取速率为1 000 r/min,萃取时间为35 min,给出相pH为2.5,接收相pH为12.0。该方法在较宽线性范围内显示了良好的线性关系（r〉0.993 6）,检出限（S/N=3）为10.4-54.2μg/L,相对标准偏差小于4.8%。7种有机酸的富集倍数为13.3-51.4,样品的加标回收率为85%-103%。该方法操作简单、快速,只需使用极少量的有机溶剂,具有绿色环保的特点,可用于果汁饮料、红茶饮料及基质特别复杂的牛奶饮料中低分子量有机酸的测定,为分析复杂基质样品提供了有益的参考。

A method has been developed for the simultaneous determination of seven low molecular weight organic acids such as tartaric acid,methanoic acid,acetic acid,lactic acid,butanedioic acid,malic acid and citric acid in several beverages by high performance liquid chromatography（HPLC） coupled with liquid phase microextraction（LPME）.Effects of extraction solvent,stirring rate,effect of salts,extraction time,temperature,pH of the acceptor phase and given phase on microextraction efficiency were investigated.The optimum experimental conditions were as follows：tributyl phosphate（TBP） as organic solven,stirring rate：1 000 r/min,extraction time：35 min,pH value of donor phase：2.5,pH value of acceptor phase：12.0.The results showed that the proposed method provided a wide linear range with correlation coefficients more than 0.993 6.The detection limits（S/N=3） ranged from 10.4 to 54.2 μg/L,and the RSDs were less than 4.8%.The enrichment folds of seven organic acids were in the range of 13.3-51.4,and their recoveries ranged from 85% to 103%.The method showed the advantages of simplicity,sensitivity,fastness and ＂green＂ for the use of very small amounts of organic solvent.It could be used for the determination of low molecular weight organic acids not only in samples such as juices and tea drinks,but also in milk drinks with complex matrixes.The study provides a useful method for the analysis of samples with complex matrixes.