建立了以二十一烷酸甲酯为内标物,同时测定奶粉中亚麻酸ARA、EPA和DHA的毛细管气相色谱方法。试样经氢氧化钾-甲醇甲酯化后、生成相应的脂肪酸甲酯,再经气相色谱分析、内标法定量。结果表明,奶粉中亚麻酸、ARA、EPA、DHA和内标物均获得良好的分离;4种被测组分色谱峰面积与其质量浓度有良好线性关系,相关系数均大于0.998;样品加标回收率为95.4%～104.7%,变异系数为2.168%～4.368%,检出限为1.0mg/100 g。该方法操作简便、快速、准确,适合批量奶粉中亚麻酸、ARA、EPA和DHA的测定。

A method using capillary gas chromatography for simultaneous determination of linolenic acid,ARA,EPA and DHA in milk powder was developed and heneicosanoic acid methyl ester was selected as the internal standard substance.The samples were firstly saponified and methylated with KOH-CH3OH.These methyl esters were then analyzed with GC by Internal standard method.The linolenic acid,ARA,EPA,DHA and internal standard substance were separated from each other.There were good linear relationships between their concentration and their peak area,and the correlation coefficient were more than 0.998.The recoveries for adding standards were 95.4% ~ 104.7%,and the coefficient of variation were 2.168% ~ 4.368%.The limits of detection were 1.0mg/100g.The method is simple,fast and accurate for the determination of linolenic acid,ARA,EPA and DHA in a lot of milk powder samples.