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一般的盐酸硫胺制剂含最测定多用矽钨酸沉淀法称重求得,而抗坏血酸片则用碘量法测其合量。但是当两者混合存在时,抗坏血酸即不能用碘量法,因为碘可以与盐酸硫胺生成沉淀。经我们实验,只要在浓盐酸存在时,用碘酸钾直接滴定抗坏血酸,借氯仿为指示剂,可得较满意的结果。这个方法的主要原理是利用抗坏血酸的还原性,以碘酸钾滴定时,第一步,碘酸钾氧化抗坏血酸生成碘(由于有浓盐酸存在此碘不与盐酸硫胺起作用),第二步碘酸钾氧化碘生成氯化碘而能使反应定量完成。
Thiamine hydrochloride preparations containing the most commonly used multi-purpose silicotungstic acid precipitation method was obtained by weight determination, while the amount of ascorbic acid tablets with iodometric method to determine the amount. However, when the two are mixed, ascorbic acid can not be iodinated because iodine can precipitate with thiamine hydrochloride. Our experiments, as long as the presence of concentrated hydrochloric acid, potassium iodate titration ascorbic acid directly, by chloroform as an indicator, can be more satisfactory results. The main principle of this method is the use of ascorbic acid reducibility, titration with potassium iodate, the first step, potassium iodate oxidation of ascorbic acid to form iodine (due to the presence of concentrated hydrochloric acid iodine does not work with thiamine hydrochloride), the second step Potassium iodate oxidizes iodine to iodine chloride and enables the reaction to be done quantitatively.