气相色谱法测定大豆油中脂肪酸组分的方法改进

Modified determination of fatty acids in soybean oil by GC

目的 建立一种快速准确的测定大豆油中脂肪酸组分的方法。方法 采用气相色谱法 ,以十一酸甲酯为内标 ,氢氧化四甲基锍为酯化试剂 ,程序升温测定大豆油中脂肪酸组分。结果 软脂酸 (C16 :0 )在 0 .115 5 6～ 0 .6 15 6mg·mL-1,硬脂酸(C18:0 )在 0 .0 4 70 8～ 0 .2 5 0 8mg·mL-1,油酸 (C18:1Δ9)在 0 .2 4 717～ 1.316 7mg·mL-1,亚油酸 (C18:2 Δ9,12 )在 0 .5 6 4 96～3.0 0 96mg·mL-1,亚麻酸 (C18:3Δ9,12 ,15)在 0 .0 7918～ 0 .4 2 18mg·mL-1的浓度范围内 ,其峰面积与内标峰面积的比对浓度呈良好的线性 ,r均在 0 .999以上。经加样回收试验 ,各组分回收率为C16 :0 =99.5 % ,C18:0 =98.1% ,C18:1Δ9=99.6 % ,C18:2 Δ9,12 =10 0 .2 % ,C18:3Δ9,12 ,15=98.2 %。酯化率在 98.2 %～ 10 0 .9%之间。酯化后的样品在 2 4h内稳定。

OBJECTIVE: To develop a simple and accurate determination method of the fatty acids in soybean oil by GC. METHODS: The fatty acids was determined after conversion to the corresponding fatty acid methyl esters using tetramethylsulphonium hydroxide. Methyl undecanoate was used as the internal standard. RESULTS: The standard curves for the five major constituents such as palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid were linear over the ranges of 0.115 56-0.615 6 mg&middotmL-1, 0.047 08-0.250 8 mg&middotmL-1, 0.247 17-1.316 7 mg&middotmL-1, 0.564 96-3.009 6 mg&middotmL-1 and 0.079 18-0.4218 mg&middotmL-1, respectively, with all of the correlation coefficients more than 0.999. The average recoveries were between 98.1%-100.2%, respectively. The rate of methylation was 98.2%-100.9%. The sample to be methylated was stable within 24 h. CONCLUSION: The assay appeared to be accurate to determine the contents of individual and total constituents of fatty acids in soybean oil.