Signal/noise with Xcalibur software

[sidabe]

I have calculated S/N using Genesis peak algorithm with Xcalibur software, but why do two neighbouring peaks have so different S/N-valuses as 2498 and 674? How does Xcalibur calculate S/N for each peak?

[lmh]

You haven't found the half of it yet: try doing your S/N in the ICIS algorithm, and prepare to be terrified (the values will increase for exactly the same peaks, possibly by several orders of magnitude!).

If you get an answer out of Thermo about this, do please post it. I'd love to know.

[MaryCarson]

Did you specify the region of "noise" or did you let the software pick it for you?

[sidabe]

I used default values from the software. Should I specify the noise-area somehow? I calculated S/N for the same sample with ChemStation from Agilent. There the software use 6 baseline-RT intervals to calculate noise and relates peaks to the nearest of the six areas to calculate S/N. Do Xcalibur use a RT-window close to each peak to calculated noise? Is that why the numbers are so different for each peak?