植物油脂肪酸甲酯化方法比较与含量测定

Methods of Methyl Esterification and Gas Chromatography Analysis of Fatty Acids in Edible Vegetable Oil

通过比较不同甲酯化方法、气相色谱升温程序，确定了植物油中脂肪酸成分的气相色谱分析方法，并对5种食用植物油的主要脂肪酸含量进行了分析和比较。结果表明：三氟化硼-甲醇快速甲酯化法具有操作简单、时间短、甲酯化率高的优点。利用CP-Sill 88高极性气相色谱柱，优化的升温程序为：初始温度170℃，保持1 min，以10℃/min升温速率升至200℃，再以1℃/min升温速率升至220℃，保持3 min，20 min内即可有效分离6种脂肪酸。用建立的方法测定5种食用植物油6种脂肪酸的含量，标准曲线的相关性好，相关系数范围为0.9994~0.9999，检出限低。

Different methods of methyl esterification and heating program of gas chromatography （GC） were compared, and optimal parameters for GC analysis of fatty acid in vegetable oil was determined. The content of essential fatty acids in 5 kinds of vegetable oil was also analyzed and compared. The results showed that boron trifluoride-methanol esterification was the optimal method for fatty acid analysis , which had advantages such as easy operation, accurate results with a high methyl esterification efficiency. A highly polar capillary column （100 m＆#215;0.25 mm i.d.＆#215;0.2 mm film thickness） of CP-Sil88 （Varian, USA） was used to separate the fatty acid methyl esters, the optimized heating program was as follows：1） 170℃for 1 min;2） increase to 200℃at a rate of 10℃/min;3） increase to 220℃at a rate of 10℃/min;4）220℃for 3 min, and 6 kinds of fatty acids can be effectively separated within 20 min. Determination of five kinds of edible vegetable oil 6 kinds of fatty acids by the established method showed a good linear ranges which correlation coefficient was from 0.999 4 to 0.999 9 and a low limit of detection.