GC uECD via MassHunter

We have been running methods on 7890A/B GCs for quite some time, and recently stood up a GCMS with a 7890B as the GC.  We configured the GCMS to run GC only for checkout, plumbed with our typical column and uECD detector and our typical running parameters.  When checking out the system in this fashion (controlled by MassHunter instead of our normal CDS), our signals come out about 10^6 higher than we see on any other system.  Does MassHunter apply some sort of multiplier when dealing with non mass spectral data?

  •  Yes, the MassHunter software uses a conversion factor and reports in "counts" instead of hertz for uECD data.  The conversion factor is 7680.

    The 7680 multiplier also applies to other GC based detectors such as FIDs and TCDs.

  • Interesting, thanks!  Do you know why the factor is 7680?  I would have thought that Hertz is already in counts per second, but am curious as to where that particular number comes from.

  • Sorry I do not know why it is specifically 7680, the conversion factor is actually carried over from the acquisition portion of the old MSD Productivity Chemstation which was in development from the late 1980s to 2013.

    It is likely an interesting part of HP/Agilent history.  While I don't know where 7680 originated, my hunch is the conversion factor is there to help GC based detectors have a similar response to MS signals when viewed in the data analysis programs.

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