Chromatography Forum

I have a compound... it's an alcohol MW 112. When I infuse in positive ESI I see an ion @ m/z 111
and when I infuse in negative mode I see ion @ m/z 113. Does that make any sense? I would expect
exactly the opposite. Pos=113 and neg=111. Thoughts?

Unfortunately it may mean that your compound didn't ionise in either mode, or at least didn't do so as well as a couple of background ions that just happen to be giving you those masses. In the absence of the signal we expect to see, there is a tendency to leap at the nearest mass we can find, and hope it's right... (well, I do that anyway).