Chromatography Forum

Hi,
Accidentally we used a high concentration of ammonium acetate buffer for a LCMS with a triple quadrupole. I know this is not good for the column, but does it harm the quadrupole?
Very often I read the advice not to use more than 20mM. Where does this number come from? What could happen?
Thanks for help

Although it's volatile, it's not very very volatile, so if you pump too much in, it will start to block things, like the aperture at the front of the mass spec (ion transfer capillary or whatever it's called in your instrument). I don't know if it will also contaminate ion optics.
My inclination with your instrument in its current state would be to see if it still works, and if it does, breathe a sigh of relief and go back to normal concentrations. If there is a check-tune option, it might be worth doing it, as that's a quick way to check that it's a happy instrument. Alternatively just run a known standard and make sure the spectral quality is as good as normal, the peak the right size, etc.
good luck!

I've used concentrations of ammonium acetate up to 3x the 20mM recommendation to try and speed up methods on a QToF. I have not noticed any issues with sensitivity loss or the instrument going out of tune, however I make sure the source is clean before beginning a run.

As far as I know the 20 mM thing is more for ion formation using ESI, if you get above that then you start to lose ionization efficiency.