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本文采用气相色谱-质谱法对亚麻酸异构体的出峰顺序和质谱特征进行了分析研究。结果表明:脂肪酸在强极性毛细管柱BPX-70(120 m×0.25 mm×0.25μm)上的出峰顺序具有一定的规律性,所测亚麻酸异构体中,出峰顺序依次为C18:3 9t,12t,15t、C18:39c,12t,15t、C18:3 9t,12c,15t、C18:3 9t,12t,15c、C18:3 9c,12c,15t、C18:3 9c,12t,15c、C18:3 9t,12c,15c和C18:3 9c,12c,15c。根据断裂规律和质谱特征分析,α-亚麻酸甲酯和γ-亚麻酸甲酯的特征离子分别为m/z 79、108(ω离子)、236(α离子)、261、292和m/z 79、150(ω离子)、194(α离子)、261、292。在8种α-亚麻酸顺反异构体中,当12位双键为顺式时,基峰离子为m/z 79,并具有明显的ω离子(m/z 108)和α离子(m/z 236);而当12位双键为反式时,α离子消失,ω离子强度减弱,并表现出离子强度m/z107>108,且同时当15位双键为反式时,基峰离子为m/z 95;而当15位双键为顺式时,基峰离子为m/z 67。双键位置和顺反构象对亚麻酸的质谱特征产生显著影响,且12位顺反异构的影响大于9位和15位的顺反异构。
In this paper, gas chromatography-mass spectrometry was used to analyze the peak order and mass spectral characteristics of linolenic acid isomers. The results showed that the peak order of fatty acid in BPX-70 (120 m × 0.25 mm × 0.25 μm) was determined. The order of the peak of linolenic acid was as follows: C18: 3 9t, 12t, 15t, C18: 39c, 12t, 15t, C18: 3 9t, 12c, 15t, C18: 3 9t, 12t, 15c, C18: 3 9c, 12c, 15t, C18: 3 9c, 12t, 15c , C18: 3 9t, 12c, 15c and C18: 3 9c, 12c, 15c. According to the rupture pattern and mass spectrometry, the characteristic ions of methyl α-linolenate and γ-linolenic acid methyl ester were m / z 79,108 (ω ion), 236 (α ion), 261,292 and m / z 79,150 (ω ion), 194 (α ion), 261,292. Among the eight α-linolenic acid cis-trans isomers, the base peak ion was m / z 79 with the c-ion (m / z 108) and α-ion (m / z 236). When the 12-position double bond is trans, the α-ion disappears and the ω-ion intensity weakens and the ionic strength m / z 107> 108. At the same time, when the 15-position double bond is trans, Ion is m / z 95; and when the 15-position double bond is cis, the base peak ion is m / z 67. The double bond position and cis and trans conformation have a significant effect on the mass spectral characteristics of linolenic acid, and the cis-trans isomerization at position 12 is more affected than the cis-trans isomerism at positions 9 and 15.