Shimadzu Prominence issue

[qfiviera]

I have the same problem as Mattias from Denmark had posted. Sometimes with 100% Acetonitrile in a line, the pressure varies and the mix is not OK. Our supplier and technical service changed the valves for new ones that Shimadzu recommended but didn´t solved the problem. Anyone knows why this happen?

[Mattias]

I have understood that it is common that acetonitrile can make the little ball inside the check valve too "sticky". If the ball cannot move freely, than you get pressure variations.

I am now testing to use 90/10 of acetonitrile/water instead of 100% acetonitrile, and so far it seems to work. But I am not sure yet.