[mandytan]

Hi,
For Acid Value test,most methods that follow the pharmacopoeia use ethanol-ether mixture. There are a few methods that use just ethanol. It seems that for some ester samples,the pink colour endpoint is difficult to detect but when ethanol-ether mixture is used, the pink colour endpoint is clear.

Why is this so? What is the chemistry of using the ethanol-ether mixture since the samples can be dissolved completely in ethanol?

Thank you.