建立了全蒸发顶空气相色谱法测定聚乙烯醇中甲醇含量的方法. 采用固定相为100%的二甲基聚硅氧烷石英毛细管柱,以氮气为载气,流速为1.0 mL/min,分流比为1:100,检测器温度为200 ℃,进样口温度为150 ℃,顶空进样,平衡温度为120 ℃,平衡时间为90 min,相关系数r为0.9979. 在此色谱条件下被测物均能得到很好的分离,甲醇峰面积与检测浓度呈良好的线性关系. 方法的检测限为0.011 mg,回收率为98.15%. 采用改变气固相比的方法测定了顶空色谱下的气固相分配系数,在0.02~0.4之间,方法符合全蒸发顶空气相色谱法应用条件. 实验建立的色谱方法灵敏、准确、简单、方便、高效. 方法可同时对9个样品进行测定,适合于企业大批量聚乙烯醇中甲醇含量的测定.
A full-evaporation headspace gas chromatographic method for the determination of methanol content in polyvinyl alcohol is established. Wherein the stationaryphase used was a silica capillary column of 100% dimethylpolysiloxane, nitrogen was used as a carrier gas with a flow rate of 1.0 mL/min, a split ratio of 1∶100, the detect temperature was 200 ℃,inlet temperature, 150 ℃. Headspace sampling was used with an equilibrium temperature of 120 ℃,the equilibrium time of 90 min, and the correlation coefficient r=0.9979.Under these chromatographic conditions, the analytes were well separated, and a good linear relationship existed between peak area of methanol and the detected concentration. The limit of detection was 0.011 mg,the recovery rate was 98.15%. The gas-solid partition coefficient using headspace chromatography was between 0.02~0.4, which was determined by the method of changing the gas and solid ratio. The method accords with the application conditions of the full evaporation headspace gas chromatography. The established chromatographic method is sensitive,accurate,simple,convenient and efficient, which can determine 9 samples simultaneously, and is suitable to determine the methanol content in the mass production of polyvinyl alcohol in factories.