紫外分光光度法测定油品中的共轭二烯烃

在化学反应－ 气相色谱法联合测定含烯汽油中共轭二烯烃质量分数的基础上，建立了用紫外分光光度法测定油品中的共轭二烯烃的含量。用化学反应－ 气相色谱法测定用作标准油样的共轭二烯烃的质量分数。在共轭二烯烃最大吸收波长２３６ ｎｍ 处绘制该标准油样的ΔＡ－ ｃ 标准工作曲线（ΔＡ 为油样吸光度与油样化学反应后吸光度之差，以消除芳烃干扰） 。测定未知油样的ΔＡ 后，可在标准工作曲线上得到共轭二烯烃的质量浓度，由此，计算出测试样品中共轭二烯烃的质量分数。该方法分析一次只需４０ ｍｉｎ ，比化学反应－ 气相色谱法少２０ ｍｉｎ ，是ＵＯＰ－ ３２６ 法分析时间的１／１０ 。

Determination of Conjugated Dienes in Petroleum Products by Ultraviolet Spectrophotometry

The content of conjugated dienes in petroleum products is determined by ultraviolet spectrophotometry.An oil sample of detected content of conjugated dienes by the combined method of chemical reaction with gas chromatography is used as standard sample.The absorptivity A 1 of standard gasoline sample and A 2 after reaction with maleic anhydride are determined at 236 nm wave length.The ΔA C standard work graph is made,ΔA being difference between A 1 and A 2.The interference with aromatic hydrocarbons is eliminated by ΔA.The ΔA of test sample is determined and the corresponding concentration C with ΔA from the standard work graph is obtained.The content of conjugated dienes is then calculated using formula(1).One normal analysis with the method takes only about 40 min,being 2/3 and 1/10 respectively of the time of combined method of chemical reaction with GC and UOP-326 method.