丙交酯中残存乳酸和水的定量测定

Quantitative Determination of Residual Lactic Acid and Water in Lactide

定量地知道丙交酯中残存的乳酸和水的量，有助于在丙交酯的提纯和聚合中对工艺过程进行更精密的控制。用甲醇钠非水滴定法、卡尔－费休法对熔点为１２７℃的丙交酯样品进行了定量分析试验，测出残存的乳酸和水的质量分数分别为０．０９％和０．０７％ 左右，回收率分别为９８．６４％ ～１０１．２％ 和９８．７４％ ～１０１．１％ 。实验表明，这两种方法可分别定量测定丙交酯中残存乳酸和水，且简捷实用。

Quantitative determination of residual lactic acid and water in lactide sample is helpful to precise control over the recrystallization and polymerization processes of the lactide. Samples of lactide with melting point 127℃ were conducted a quantitative analysis test by using non aqueous titration with sodium methoxide and Karl Fischer method. Residual lactic acid and water contents of ca. 0.09% and 0.07% were determined. The recovery rates were 98.64%～101.2% and 98.74%～101.1% respectively. The test showed that both methods were suitable for the quantitative determination of residual lactic acid and water in lactide, they were simple, convenient and easily applicable.