Chromatography Forum

Hi!
Recently I started to have troubles with the reference masses detection. This happen just in ESI positive mode, in negative I can detect ref masses.
Tunes can be done without problems.
I´m wondering if this can be related with the capilar condition, I red some topics about of the decreasing sensibility in positive mode after long use of the capilar.
I really appreciate some suggestions.
Regards.

You can change nebulizer pressure from 0 to 60 and see what you see For example.
But i think you need to clean Ion Source and capillary after ion source (especially if you see tune of ref in negative, after switching you see it few minutes in positive and then you don't see it) .