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澱粉試液在檢驗室中是比較常用的一種東西,在碘滴定法中沒有不用它做指示劑的。但澱粉試液變色的靈敏度與澱粉試液本身的好壞有極大關係;若在滴定時已發現澱粉所顯示的顏色是紅紫色而不是深藍色時,則澱粉試液本身已失去效用了;因澱粉試液時間一久極易變壞,如因微生物繁殖而促使澱粉腐敗水解後,就不能再與I_2吸附而顯藍色。其他如碱度、醇在溶液中的影響,都會使澱粉試液顯色的靈敏度改變。故在檢驗中我們所用的澱粉指示劑多爲新鮮配製;其中也有加一定的防腐劑,而能長期保存不壞的。防腐劑很多,其用量不一,如1.加少量的HgI_(20)
Starch test solution in the laboratory is more commonly used in a kind of thing, in the iodometric titration did not do it without indicators. However, the sensitivity of starch test solution discoloration and starch test solution itself is very good or bad; if the titration has been found when the color of the starch is purple rather than dark blue, then the starch test solution itself has lost its effectiveness; starch test solution time A long time very easy to deteriorate, as a result of microbial propagation and starch corruption caused hydrolysis, it can no longer be with I_2 and blue. Others such as alkalinity, alcohol in solution, will make the color sensitivity of starch test solution changes. Therefore, we used in the inspection of starch indicator mostly fresh preparation; which also added a certain amount of preservatives, and long-term preservation is not bad. Many preservatives, the amount of different, such as 1. Add a small amount of HgI_ (20)