胶束电动色谱法分析奶中两种主要的共轭亚油酸异构体

以胶束电动色谱法对奶样中共轭亚油酸主要的两种异构体进行了分析。在优化条件下(80 mM pH9.0的磷酸盐缓冲液,54 mMSDS,4%(w/v)β-CD,8 M尿素,4%(v/v)乙醇作为运行缓冲液,分离电压25 kV,柱温20℃),胶束电动色谱可在15 min内对奶样中两种主要CLA,即9c,11t-CLA和10t,12c-CLA进行分离测定,最低检出限为0.081 ng/mL。分析结果显示,不同处理奶样中的CLA含量差异显著(P<0.001),但CLA的组成相近,其中的10t,12c-CLA含量差异不显著P=0.999,约为3%;不同品种奶样,如牛奶、水牛奶和羊奶中的CLA含量差异显著(P<0.001),其中CLA含量次序为牛奶>羊奶>水牛奶,并且不同品种奶的9c,11t-CLA与10t,12c-CLA比例差异显著(P<0.05)。

Separation of Conjugated Linoleic Acid Isomers in Milk by Micellar Electrokinetic Chromatography

A micellar electrokinetic chromatography method was used to analyze the major conjugated linoleic acid(CLA) isomers in milk.Under the optimized conditions(80 mM borate(pH 9.0),54 mM sodium dodecyl sulphate,4%(w/v) β-cyclodextrin,8 M urea,4%(v/v) ethanol,25 kV and 20 ℃),the major CLA isomers 9c,11t-CLA and 10t,12c-CLA could be separated within 15 min by MEKC.Limit of detection of this method is 0.081 ng/mL.The results indicated that there was a significant difference in the total CLA content among raw milks,pasteurized milk,UHT milk(P<0.001).However,the content of 10t,12c-CLA from all samples was similar(3%).The result also showed there was a significant difference in the total CLA content and 10t,12c-CLA content among the cow milk,goat milk and buffalo milk.