超高效液相色谱法测定生物柴油中的11种脂肪酸及脂肪酸甲酯

建立了采用超高效液相色谱(UPLC)-蒸发光散射检测器(ELSD)测定生物柴油中11种常见的脂肪酸及脂肪酸甲酯含量的方法。这11种常见的脂肪酸及脂肪酸甲酯为豆蔻酸、亚油酸、棕榈酸、油酸、亚麻酸甲酯、硬脂酸、亚油酸甲酯、棕榈酸甲酯、油酸甲酯、芥酸和硬脂酸甲酯。样品经提取后用甲醇溶解,采用Acquity UPLC BEH Phenyl C18柱(100 mm×2.1 mm,1.7 μm)分离，乙腈-水（体积比为3∶1)混合液为流动相进行等度洗脱，采用的ELSD条件为增益80，漂移管温度为45 ℃，载气压力为172 kPa，雾化器为冷却模式，并用外标法进行定量分析。结果表明，在一定的质量浓度范围内,峰面积的对数和质量浓度的对数线性关系良好。与其他检测生物柴油成分的方法相比,该方法简单,分离效果好,速度快,特别是此方法可以同时实现脂肪酸及脂肪酸甲酯的分离,并进行定量分析,能有效测定反应的进行程度,从而满足生物柴油工艺研究的需要。

Determination of 11 fatty acids and fatty acid methyl esters in biodiesel using ultra performance liquid chromatography

A method for the determination of 11 familiar components in biodiesel was developed using ultra performance liquid chromatography with evaporative light scattering detector (UPLC-ELSD). The components were oleic acid, methyl cis-9-octadecenoate, linoleic acid, methyl linolenate, stearic acid, methyl octadecanoate, methyl linoleate, palmitic acid, methyl hexadecanoate, erucic acid, and myristic acid. The sample was dissolved in methanol after extraction from the products. The separation column was an Acquity UPLC BEH Phenyl C18 (100 mm × 2.1 mm i.d., 1.7 μm) and the mobile phase was acetonitrile-water (3:1, v/v). An isocratic elution program was utilized for the separation. The flow rate was 0.3 mL/min and the column temperature was 40°C. The parameters of ELSD were as follows: the plus was 80; the temperature of the drift tube was 45°C; and the eluant gas pressure was 172 kPa. The sample was detected by ELSD in only 5 min. The calibration curves of 11 components showed good linearity in the range of 0.01-10 Pg with the correlation coefficients greater than 0.997. In comparison with other methods, this method is simple, fast, and has good separation efficiency. The fatty acids and fatty acid methyl esters were separated in one step, and thus, the extent of reaction can be confirmed by the determination of their contents. This method can be routinely used for the determination of fatty acids and fatty acid methyl esters in the reaction products and final biodiesel.