气相色谱法测定硬脂酸中的脂肪酸组分

Determination of Fatty Acid Composition in Stearic Acid by GC

建立了气相色谱法测定硬脂酸中脂肪酸的组成。检测前先采用甲酯化的方法,将硬脂酸中的脂肪酸转化为脂肪酸甲酯。色谱柱为DB-FFAP毛细管柱(30 m×0.32 mm×0.5μm),程序升温,起始温度为70℃,保持2 min,再以5℃/min的速率升温至240℃,保持24 min。进样口温度为220℃,氢火焰离子化检测器温度为260℃,分流比为10∶1。采用峰面积归一化法计算各脂肪酸甲酯含量。结果显示,所考察的16个脂肪酸甲酯峰均可有效分离,各组分在1~100μg/ml内线性关系良好,精密度和稳定性均良好,各脂肪酸的检出限均低于3.4μg/g。此外,对国内外7个厂家的25批样品进行了检测,均符合现行标准规定。

A gas chromatography method was established to determine the composition of fatty acids in stearic acid.Before detection,the methyl esterification reaction was conducted to convert the fatty acids in stearic acid into fatty acid methyl esters.The DB-FFAP capillary column(30 m×0.32 mm×0.5 μm) was used.The initial column temperature was set at 70 ℃ for two minutes,followed by incraesing to the final temperature of 240 ℃ for twenty-four minutes with a rate of 5 ℃/min.The temperature of the injection port was 220 ℃,the temperature of the flame ionization detector was 260 ℃,and the split ratio was 10∶1.The peak area normalization method was used to calculate the content of each fatty acid methyl ester.The results showed that all peaks of the sixteen fatty acid methyl ester could be effectively separated.It was linear for all of them in the range of 1-100 μg/ml.The precision and stability were good,and the detection limit of each fatty acid was lower than 3.4 μg/g.In addition,twenty-five batches of stearic acid samples from seven domestic and foreign manufacturers were tested,and they all met the current standards.