气相色谱-质谱法测定食品中的反式脂肪酸

[目的]采用气相色谱-质谱联用技术定性定量分析食品中的反棕榈油酸、反油酸和反异油酸3种反式脂肪酸。[方法]从食品中提取的脂肪在碱性条件下甲酯化;Hp-INNOW ax（30 m×0.25 mm×0.25μm）毛细管柱上分离,经质谱检测器检测;通过标准品的保留时间、与标准谱库对照的方法定性;采用外标法定量;通过相关公式计算出样品反式脂肪酸含量。[结果]反式脂肪酸甲酯及其异构体分离效果较好;在0.001~0.010 mg/m l浓度范围内线性良好（r〉0.999 5）,相对标准偏差为0.648%~2.430%,方法回收率为89.1%~102.0%,3种反式脂肪酸甲酯的检出限分别为0.800、0.875、0.840μg/m。l[结论]该方法准确、可靠、简捷,适用于食品中主要反式脂肪酸的测定。

Test of the Trans Fatty Acid in Food with Gas-chromatography-Mass-spectrometry

[Objective] 3 types of different trans-fatty acid:reversed palmitic acid,elaidic acid and antioleic acid were qualitatively and quantitatively analyzed with gas chromatography-mass spectrometry.[Method] The fat extracted from food was methylated under the condition of alkaline,isolated in the capillary column of Hp-INNOWax(30 m×0.25 mm×0.25 μm) and detected with the mass spectrometry.The character of the sample was qualitatively identified with the CK from Standard Spectral Library based on the retention time of the standard sample and quantitatively identified with the method of external standard.The content of trans-fatty acid in the sample was measured with a relevant formula.[Results] The methyl esters of trans-fatty acid were better isolated with its isomer.There was good linearity(r>0.999 5) in the concentration range of 0.001-0.010 mg/ml,with the relative standard deviation of 0.648%-2.430% and the recovery of 89.1%~102.0%.The detection limit of the methyl esters of 3 types of different trans-fatty acids was 0.800,0.875 and 0.840 μg/ml,respectively.[Conclusion] This method was accurate,reliable and simple,which was suitable for the test of the main antieiso-fatty acid in food.