Is this possible?

I need to calculate the percentage of my active compared to the active in the previous standard injection and multiple times across the sample set as such:

Vial 1: Standard
Vial 2: Sample (amount of component/amount of component in previous standard)*100
Vial 3: Standard
Vial 4: Sample (amount of component/amount of component in previous standard)*100. 

etc etc. I also need the sample and standard labels for quantifying the samples so its tricky. I tried a custom field along the lines of:
(%.%.%(Area)/%.%.%(Area))*100 but this doesn't work, is it better to use Excel for this or is there a way for Empower to do it? 

Best Answer

    Accepted Answer
    I think what Dan alludes to is probably the simplest as you are probably using a lot of clear calibrations with all those standard injections anyway.  Something like: Amount/S%..(Value)*100 should do the trick where S1/S2/etc. can be the standard label in the sample set.  Empower should default to the most recent "value" which would inherently be the one from the preceding standard so long as you are using "Normal" for the processing instruction or at least keeping them ordered as such and not processing all standards, then all samples.


  • I suspect that most of this could be done "on the fly" via several "Clear Calibration" and "Normal" entries in your SSM. If you will eventually want something more conventional, it may be best to export to Excel and do the more recursive calculations there, just to avoid having many, many results for each and every sample injection.
  • Thanks MJS, I tried the layout of the sample set as you suggested and it worked exactly as I wanted, thankfully to the most recent preceding standard which I was worried about as I know non-summary intersample custom fields always use the most recent or highest result ID but I wasn't sure would that apply to a summary. 
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