非衍生化-气相色谱法测定羊奶中短中链游离脂肪酸

Determination of Free Fatty Acids in Goat Milk by Gas Chromatography without Derivatization

建立羊奶中短中链游离脂肪酸(free fatty acids,FFA)的非衍生化-气相色谱分析方法。其测定过程包括羊奶中脂肪的提取、FFA的分离和气相色谱测定3个部分。首先用乙醇-乙醚-正庚烷将羊奶中脂质进行提取,然后采用氨丙基固相萃取柱将FFA进行分离,最后用气相色谱法测定FFA含量。采用外标法测定羊奶中FFA的回收率,以此作为FFA的校对系数。结果表明,羊奶中长链FFA的回收率较高,而短链FFA的回收率较低,尤其是C2:0和C4︰0回收率仅为23.9%和78.5%,但其回收率相对稳定,相对标准偏差小于0.04%,可校对测定过程中FFA的损失。

A method was developed for the determination of free fatty acids(FFAs) in goat milk by gas chromatography(GC) without derivatization. The process includes three parts: the extraction of goat milk lipids, the separation of FFAs and the determination by gas chromatography. Firstly, the milk lipids were extracted with ethanol/ether/n-heptane, and then FFAs were isolated on an aminopropyl column. Finally, the FFAs were identified and determined by gas chromatography. The external standard method was applied to determine the recoveries of FFAs in the goat milk, which acted as the calibration coefficients of FFAs. The results showed that the recoveries of long chain FFAs were higher than those of short chain FFAs, especially for C2:0 and C4:0 with values of 23.9% and 78.5%, respectively. The recoveries were stable with relative standard deviations blew 0.04%.