反吹气相色谱法测定甲苯、异丙基甲苯中的微量水

Determination of Trace Water in Toluene and Cymene by Backflushing Chromatography

利用反吹气相色谱法分析异丙基甲苯吸附分离过程中的原料(异丙基甲苯)、洗脱剂甲苯及分离后产品中的微量水含量。样品注入色谱柱后,由于柱填充物GDX—104的憎水性,水峰在23.8s内流出柱子。待水峰流出,立即打反吹,使未完全分离的芳烃由进样口吹出,节省了分析时间。分析条件为Φ4mm×2000mm不锈钢色谱柱GDX—104,检测器TCD,进样量20μL,柱温190℃,检测器190℃,汽化温度240℃,桥流200mA,氢气作载气,灵敏度为28μV/μg·mL^(-1)。经实际应用发现,此方法分析线性范围为2—400μg/mL,对于含水100μg/mL的样品变异系数CV%=2.2％(n=11)。用外标法定量。每个样品的分析时间为4min。

The 20μL sample containing trace water was injected in a column φ4mm × 2000mm of GDX-104 (60-80mesh) with H2 as carrier gases (66. 7mL/min) and oven operation tempereture was 190℃. TCD was used for detection of 2μg/mL to 400μg/mL water. The bridge electrcial current was 200mA. Backflushing time was 4min. While the concentration of water was 140μg/mL (retention time 23. 8),The CV% was 2. 2%. The detection limit was 2μg/mL,The senstivity was 28μV/μg · mL-1.