Hello, I am trying to remove ammonium acetate from a complex sample of very small and hydrophilic compounds for dissolving it in 80 percent of Acetonitrile for HILIC separation. Ammonium acetate interferes by forming a second phase and maybe retaining some of the compounds. I tried it by speed vac but I have to dry and redissolve the sample many times. Freeze-drying or other method could be more efficient ?

Dissolve your matrix in chloroform where ammonium acetate is insoluble, remove the supernatant ammonium acetate flakes and then remove the chloroform by using a rotavap/under vaccum. This will workout well to separate your compound of interest.

Thank you.

I would like to know if a solution of ammonium
acetate, when in pH 7,0, continue reacting or the
reaction that formed the solutions stops.
My solution after 3 months loses eficience.
What should i do for stabilize the solution?

Thanks

although I do not understand your question I can say that ammonia can react with carbon dioxide from the air if the solution is left open. Perhaps this is what you refer to? Acetate will continue to oxidize in solution in the presence of air, albeit slowly.

I apologize if this is not helpful.

I think that reaction is slow at temperature below room. You can keep you ammonium acetate in the cooler and take it out when you need to use it. Temperature might effect pH (I think)