Profile or centroid??

[Beaker]

Hi,

Could someone please explain the difference between centroid and profile data in LCMSMS?

We've noticed that the number of counts given for analyte peaks when data is collected in profile mode is up to 10 times that for the same analytes when centroid data is used. Can anyone explain this please?

The TIC and extracted ion chromatograms don't look any different between the two, suggesting there is no sensitivity gain in using the profile method!

Thanks in advance.
Phill

[MaryCarson]

Have you looked at the size of your raw data files? Usually, profile file are huge. With the instruments I've used, the centroid files are much smaller, as for each m/z, only the "centroid"--a m/z value and its corresponding height--is stored rather than the entire peak "profile." You lose some information, but for routine analysis you usually don't need that info. There's probably a visual of this somewhere on the net.