Has anyone experienced getting [M+NH3+H+] peaks alongside [M+H] peaks in ESI +ve mode on a orbitrap HRLCMS? I am using acetonitrile as solvent which is highly unlikely to give NH3. Also, there was no ammonium acetate or ammonium hydroxide added in mobile phase buffers.
Ammonia, in many forms, is often found on glassware used with HPLC systems. Your detector will easily pick up very small amounts of it.
how well can you distinguish between (M+NH4)+ vs (M+H3O)+ ?
Alexandre Podtelejnikov My instrument has a precision of 5ppm, so M+NH4 and M+H3O are well distinguished
I am going with William, once ammonia has been used on an instrument, it is often difficult to get rid of again. So Your ammonia aducts might be results of operations of last week or even last month.
However, if really never ever ammonia has been used on the machine it should not happen.
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