气相色谱法测定车用汽油中含氧化合物和苯胺类化合物

利用中心切割技术和双毛细管色谱柱系统,采用两次进样的方式,建立了气相色谱测定车用汽油中含氧化合物和苯胺类化合物的分析方法。第一次进样分析,组分首先进入非极性DB-1色谱柱(30 m×0.32 mm×1.0μm),按沸点由低到高的顺序分离,通过电磁阀切换将沸点小于2-己酮的组分切割至强极性GS-OxyPLOT色谱柱(10 m×0.53 mm×10μm)或CP-Lowox色谱柱(10 m×0.53 mm×10μm),其余重烃组分通过阻尼柱进入FID检测器。在GS-OxyPLOT或CP-Lowox色谱柱上,烃类组分与含氧化合物分离并进入检测器检测,消除了大量的烃类组分对含氧化合物测定的影响。第二次进样分析,设定电磁阀切换时间为间-甲基苯胺从非极性色谱柱流出的时间,苯胺类化合物在GS-OxyPLOT或CP-Lowox色谱柱上与烃类和含氧化合物分离并进入检测器检测。以乙二醇二甲基醚为内标化合物进行内标法定量。实现了在一套系统上同时测定车用汽油中添加的甲基叔丁基醚(MTBE)、甲醇、甲缩醛、乙酸仲丁酯、乙酸乙酯、苯胺、邻/间/对-甲基苯胺和N-甲基苯胺的含量,各组分的检测范围为0.01%~10%(质量分数),回收率为86.0%~102.6%。该法可以为车用汽油的质量控制提供有效的检测手段。

Determination of oxygenates and anilines in motor gasoline by gas chromatography

A test method for the determination of oxygenates and anilines in motor gasoline was established using a gas chromatograph (GC) with heart-cut accessories and two chromatographic columns. A nonpolar DB-1 column (30 m×0.32 mm×1.0 μm) was used as the pre- column and a polar GS-OxyPLOT or CP-Lowox column (10 m×0.53 mm×10 μm) was used as the analysis column. In a test run, the gasoline sample was first separated according to the boiling points on the nonpolar column. By solenoid valve switching, the compounds of boiling points below 2-hexanone were cut to the GS-OxyPLOT or CP-Lowox column, whereas the other compounds were put through a restrictor to a flame ionization detector (FID). The oxygenates were separated from the hydrocarbons on the GS-OxyPLOT or CP-Lowox column and detected by the FID. When a second run was performed, the solenoid valve switching time was set at the point when m-methyl aniline was all eluted from the nonpolar column into the polar column. Anilines were separated from hydrocarbons and oxygenates on the GS-OxyPLOT or CP-Lowox column. Dimethoxy-ethane was used as the internal standard for quantitation. Methyl tert-butyl ether (MTBE), methanol, methylal, sec-butyl acetate, ethyl acetate, aniline, N-methyl aniline and o/m/p-methyl aniline in motor gasoline were detected and quantitated. The linear ranges were 0.01%-10% (mass fraction) with recoveries of 86.0%-102.6%. The method provides an effective way for quality control of motor gasoline.