Qualitative Analysis Chromatogram subtraction

Question

Hi, I am using MassHunter Qualitative Analysis B.07.00. I am trying to subtract one TIC from another TIC. When I did chromatogram subtractions on Qualitative Analysis, I find the retention time of the peaks have to be exactly the same on two TICs, otherwise the chromatograms won&rsquo;t be subtracted correctly. It seems like Qualitative Analysis doesn&rsquo;t allow a retention time drift for chromatogram subtraction, is there a way to do that, or other software that can do this?

howard_sanford · Accepted Answer

Hi luobo109 , 
 As far as I know the chromatogram subtraction in Qual only works at the 2D data level. In other words it subtracts the signal at a given time in one data file from another. It does not alter any extract spectrum from the subtracted chromatogram as again it is only working on the 2D data. So what you are observing in Qual is the expected behavior. 
 Quant and Unknowns Analysis offer some blank subtraction options, but they do no change the reported peak area for a given compound. In Quant, depending on the technique used, it can adjust the reported concentration. In Unknowns Analysis blank subtraction is used as a simple filter to determine whether or not to report a compound in a sample, but makes no changes to the report concentrations or responses.

Qualitative Analysis Chromatogram subtraction

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