库仑滴定法快速测定烟用香精的酸值

Rapid determination of acid value of tobacco flavors by coulometric titration

为建立库仑滴定法测定烟用香精的酸值,采取铂电极-铂丝电极为电解电极对,锑电极-饱和甘汞电极为指示电极对,以0.5 mol/L氯化钾溶液为电解质,利用电解生成的OH~-与样品中游离酸进行中和反应,滴定溶液pH至8.0,通过电解滴定至终点的时间,按照法拉第电解定律计算得到烟用香精的酸值;并进行加标回收率实验。结果表明:(1)该方法的回收率范围为96.50%~102.47%,重复性实验结果的相对标准偏差均低于1.4%。(2)应用该方法测得20种香精样品的酸值与烟草行业标准规定的电位滴定法无显著性差异。(3)该方法操作便捷,耗时较短,结果精密度与准确度较好,适用于实际生产中产品的质量检测。

To determine the acid values of tobacco flavors by coulometric titration,the platinum electrode-platinum wire electrode was used as the electrolytic electrode pair,antimony electrode-SCE(saturated calomel electrode)was used as the indicating electrode pair,and 0.5 mol/L potassium chloride solution was used as the electrolyte.The solution was titrated to the pH value of 8.0 by the reaction of electrolytically generated hydroxide ions with free acids in a tobacco flavor sample.Then,the acid value of an experimental tobacco flavor could be calculated by the electrolytic time reached to the titration end point according to Faraday’s electrolysis laws,and the spiked recovery experiments were also conducted to validate the method.The results showed that:1)The recovery range of this method was 96.50%-102.47%,and the relative standard deviations among repeated test results were all less than 1.4%.2)The acid values of 20 tobacco flavor samples determined by this method showed no significant difference with the potentiometric titration method specified in the tobacco industry standard.3)The coulometric titration method was suitable for quality control in actual production with convenient operation,less time consuming,and satisfactory precision and accuracy of results.