unusual EIC

[Robotjock]

Virtual Colleagues.

I when I extract the IC for 477 m/z ion from the mass spectra I obtain the unusual (to me) plot (last of 4). The first plot is the TIC, second plot is the MS of the elaidic acid peak (1st integrated peak). Third plot is the EIC for 283 m/z ion, which is elaidic acid. This plot is what I expect to obtain. Given the relative abundance of 283 and 477 ions are similar, I do not understand the difference is the EICs. Thanks for the feedback.

The data was collected on an Agilent LC-MSD SL 1956B. Mobile phase is 70/30/0.05, ACN/Water/TFA. Zorbax SB-CN column. Postive ES mode.

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regards,

[lmh]

I'm surprised no one has replied.
477 is probably a background ion in your runs. It is present at high levels all the time, which is why you see it in the spectrum, and why the EIC looks like it does. There is a negative peak in the EIC of 477 at the time the major peak elutes from the TIC, probably indicating that whatever caused the major peak suppresses ionisation of the background ion.

[Robotjock]

Imh,

Thanks for your input.

regards