库仑滴定法快速测定白酒中总酯的含量

Rapid Determination of Total Ester in Chinese Liquor by Coulometric Titration

提出了库仑滴定法测定白酒中总酯含量的方法。以铂电极为工作电极对,pH复合玻璃电极为指示电极,0.80 mol·L^(-1)硫酸钾溶液为支持电解质,通过恒电流电解生成的H~+滴定预处理后样品中剩余的OH^(-),直至滴定终点pH 7.70,根据法拉第电解定律测得样品中总酯的含量。结果表明:测定过程约10 min完成。按标准加入法进行回收试验,回收率为88.0%~106%。方法用于实际白酒样品中总酯含量的测定,测定结果与国家标准规定的电位滴定法测定结果无显著性差异。

A method for determination of the total ester in Chinese liquor by coulometric titration was proposed. The platinum electrodes were used as working electrode pairs, with pH composite glass electrode as indicating electrode, and 0.80 mol·L^(-1)potassium sulfate solution as supporting electrolyte. Hgenerated by constant current electrolysis was used to titrate the remaining OHin the sample after pretreatment, till to pH 7.70 for titration end-point. The total ester in sample was determined by Faraday′s law of electrolysis. As shown by the results, the whole determination process could be completed about 10 min. Test for recovery was made by standard addition method, giving results in the range of 88.0%-106%. The proposed method was applied to determination of the total ester in actual Chinese liquor samples, and there was no significant difference between the determination results by this method and those by potentiometric titration specified in the national standard.