气相色谱法测定混合生物柴油中三脂肪酸甘油酯含量

DETERMINATION OF TRIGLYCERIDES IN MIXED FUEL OF DIESEL AND BIODIESEL BY GAS CHROMATOGRAPHY

混合生物柴油中的脂肪酸甲酯含量是产品质量的重要指标。采用红外光谱法根据酯基官能团的吸光度测定脂肪酸甲酯的总量时,不能区分酯基官能团是来源于脂肪酸甲酯还是未转化或混入的油脂原料中的三脂肪酸甘油酯。采用高温气相色谱法,考察了混合生物柴油中混入不同类型的油脂原料时的色谱分离情况,以三癸酸甘油酯作内标物,建立了混合生物柴油中三脂肪酸甘油酯含量的测定方法。该方法的检测限为0.01%(w)。当三脂肪酸甘油酯含量大于0.1%(w)时,测定的回收率大于91%,相对标准偏差小于6%,可以满足一般测定的要求,需要时可以作为红外光谱法的补充,用于分辨酯基官能团的来源。

The content of fatty acid methyl ester in mixed fuel of diesel and biodiesel is an important specification for the product.Using IR spectrum method to determine the total amount of fatty acid methyl ester,the weakness is that it cannot well distinguish the absorbency of ester functional group comes from fatty acid methyl ester or unconverted oil feed,mainly triglycerides.Thus,investigation of using high temperature gas chromatographic method to separate mixed biodiesel fuels adding various kinds of oil feed was carried out,and a method for the determination of triglycerides in mixed biodiesel fuel was established with tricaprin as internal standard.The determination limit（mass） was 0.01%.When the content of triglycerides in fuel was over 0.1%,the recovery rate reached more than 91% and relative standard deviation was less than 6%.Above results indicates that this method could meet the demand of conventional analysis,it could be used as a supplemental method to help distinguish the source of ester functional group for IR spectrum method in need.