What resolution should I use in negative or positive mode?
Resolution: 0.5-0.7 at 1000 m/z u/sec. 0.25 at 500 m/z u/sec.
- Negative mode (applies a negative voltage to the source): acidic compounds as the acid loses a proton (general buffers: ammonium, triethylamine)
- Positive mode (applies a positive voltage to the source): alkaline compounds, as accepts a proton.
In positive mode, sensitivity increases in acidic media with TFA, acetic acid or formic acid buffers.
It would be interesting to have both modes in a single run.
This is possible with the new Mass analysers proposed by Interchim.
Triethanolamine and triethylamine should be avoided, along with DMF and DMSO if possible.
Phosphate and perchlorate buffers etc. must not be used.