外标-气相色谱-质谱法准确测定猪肉中的14种脂肪酸

Accurate determination of fourteen fatty acids in pork by external standard-gas chromatography-mass spectrometry

采用外标-气相色谱-质谱法准确测定了猪肉中14种脂肪酸的含量和百分含量,并与峰面积归一化法的结果进行了比较,两种方法都测出猪肉中8种主要的脂肪酸:肉豆蔻酸、棕榈酸、棕榈油酸、硬脂酸、反油酸、油酸、亚麻酸、亚油酸。峰面积归一化法测定高含量脂肪酸结果较为准确,测定低含量脂肪酸则误差较大。同时对相关国标中的前处理方法进行了改进,脂肪提取用溶剂浸提法代替索氏提取法,脂肪酸甲酯化用碱常温催化酯交换法代替先皂化、再甲酯化的方法。方法学试验结果表明:14种脂肪酸甲酯的线性回归相关指数R2皆大于0.992、加标回收率皆大于75%、而样品平行测定3次的相对标准偏差RSD皆小于5%。该方法简便、环保、准确性好、精密度高,完全满足猪肉中脂肪酸的分析需要,可广泛应用于猪肉等肉类样品中脂肪酸的日常检测工作。

The contents and percent contents of fourteen fatty acids in pork has been accurately determined by external standard--gas chromatography-mass spectrometry and compared with the percent con- tents determined using peak area normalization method. Both methods have shown that the eight primary components in pork are myristic acid, palmitic acid, palmitoleic acid, stearic acid, elaidic acid, oleic acid, linolenic acid and linoleic acid. As for nomalisation method, the results of high-content fatty acids were more accurate, while those of low-content fatty acids produced some errors. Meanwhile, the sample preparation procedures in relevant Chinese Standards have been improved. Soxhlet extraction was replaced by solvent extraction to obtain fat; the two-step method of saponification before methyl esterification was replaced by the one-step method of ester exchanging reaction catalyzed by base at room temperature to obtain fatty acid methyl ester （FAME）. The methodological study showed that for all the fourteen fatty acids, R2 of linear regression were above 0. 992, the recoveries were above 75% , the relative standard deviations （RSDs） of three parallel sample determinations were below 5%. With its simplicity and environmentallyfriendliness, the accuracy and precision of the method have all met the requirements of daily analysis of fatty adds in pork.