橄榄油和山茶油中5种未衍生化脂肪酸含量的分析对比

Comparative analysis on determination of five underivatized fatty acids in olive oil and camellia oil

建立了超高效合相色谱-质谱(UPC2-M S)法快速分析橄榄油中软脂酸、硬脂酸、油酸、亚油酸、亚麻酸等5种脂肪酸的方法,并比较了橄榄油和山茶油中上述5种脂肪酸的含量差异。以标准品为对象比较了4种色谱柱的分离效果,进行色谱柱的筛选;考察了流动相中助溶剂、柱温和背压、补偿溶剂对分离的影响。助溶剂对保留时间和色谱峰形有影响;降低背压,升高柱温,保留时间增大;补偿溶剂对目标物的离子化效率影响不大。经过优化,确定采用UPC2BEH2-EP色谱柱,以超临界CO2-甲醇/乙腈(V/V=1:1)为助溶剂,在50℃柱温和13.79 M Pa背压条件下,以质谱检测器进行检测,3 min内完成植物油样品的分析。橄榄油和山茶油中的脂肪酸组成比较接近,属于高油酸(含量均>76%)类型的植物油,总不饱和脂肪酸含量远高于饱和脂肪酸,且该结果与气相色谱法测定结果无显著差异。

A fast analytic method of 5 common fatty acids in olive oil was developed by ultra-performance convergence chromatography（ UPC2）. The 5 fatty acids were palmitic acid,stearic acid,oleic acid,linoleic acid and linolenic acid,and the content differences in the olive oil and camellia oil were compared. The initial screening of four stationary phases was investigated with the standard mixture of five fatty acids. Then,the effects of chromatographic parameters on separation were studied including cosolvent,column temperature,back pressure and compensation of solvent. The injection volume had significant impact on the peak shape. With the variation in organic cosolvents in the mobile phase,some changes in peak shape and retention time were observed in separation. Both decreased back pressure and increased temperature increased the retention time. Finally,a fast analytical method using UPC2,on a UPC2 BEH 2-EP column,methanol / acetonitrile（ V / V = 1 ∶ 1） as cosolvent,under 50 ℃ and 13. 79 MPa,was developed to separate olive oil in less that 3 min. The result showed that the composition of fatty acids in olive oil and camellia oil was close,the 2 oils belonged to the high oleic acid（ content 〉76%） type of vegetable oil,and the total content of unsaturated fatty acids is much higher than the saturated fatty acids. Moreover,the results were no significant difference between the UPC2 and conventional gas chromatography.