容量法测定PE－淀粉薄膜中淀粉的含量

Volumetric Determination of Starch in PE-Starch Film

用四氯化碳溶解样品后去与稀酸溶液一起于水浴中加热回流使淀粉进入水相，除掉四氯化碳后在沸水浴中加热回流使淀粉水解为葡萄糖。在加热条件下，以次甲基蓝作指示剂，用样品溶液滴定标定过的碱性酒石酸铜溶液。计算葡萄糖的含量，再换算成淀粉的含量。本法测定结果回收率９９．８１％，变异系数０．１６％，方法准确可靠。

After the sample is dissolved by CC14, the starch in the sample is allowed toenter into water phase by heating and refluxing with a dilute acid in the water bath. Afterthe CC14is removed, the starch is converted into glucose by hydrolysis under heating andrefluxing in the boiling water l):lth. Under heating condition, the solution of basic coppertartate that has been standardized is titrated by the solution of sample and methylene blueis used as indicater. The content of gluscose is calculated and converted into the content ofstarch. The recovery for the method is 99.81 % and the variation coeffcient is 0.16%. Themethod is accurate and riliable.