气相色谱法测定大豆油中脂肪酸组分的方法改进

 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 56～0.615 6 mg·mL_-1，硬脂酸(C18:0)在0.047 08～0.250 8 mg·mL_-1，油酸(C18:1^Δ9)在0.247 17～1.316 7 mg·mL_-1，亚油酸(C18:2^Δ9,12)在0.564 96～3.009 6 mg·mL_-1，亚麻酸(C18:3^Δ9,12,15)在0.079 18～0.421 8 mg·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%，C18:1^Δ9=99.6%，C18:2^Δ9,12=100.2%，C18:3^Δ9,12,15=98.2%。酯化率在98.2%～100.9%之间。酯化后的样品在24 h内稳定。结论内标法能够准确地测定大豆油中脂肪酸各组分含量及总含量。

Modified determination of fatty acids in soybean oil by GC

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·mL_-1,0.047 08～0.250 8 mg·mL_-1,0.247 17～1.316 7 mg·mL_-1,0.564 96～3.009 6 mg·mL_-1 and 0.079 18～0.421 8 mg·mL_-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.