Peptides remaining in more viscous bottom phase, instead of at interphase precipitation help.

27 July 2017 1 9K Report

I'm trying to make MS Standards using peptides bought from Sigma.

I'm using TFA 75% / Cold diethyl ether for precipitation.

Most are precipitating at the interphase, however some remain in the oily bottom phase. How can I retrieve them/purify them ? And why would they not precipitate?

Julius Pavlov

Your acid may be too strong, causing some degree of acid hydrolysis of your peptides. Try something like 0.1M HCl instead, or simply repeated precipitation in ether only.

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