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MassHunter Quant S/N problems

Question asked by jad on May 22, 2020
Latest reply on May 28, 2020 by howard_sanford

I am analyzing GC/MS data with MassHunter Quantitative Analysis Build 10.1.733.0. I have noticed a few problems with the S/N.

1. When I zero peaks for the quant and qual ion, the S/N for the qual ion becomes infinity. This doesn't happen immediately, but after I Quantitate Sample (F7) whatever value was there for S/N becomes infinity. Why is this infinity? Shouldn't this be zero (zero signal divided by some quantity of noise)? This only happens for the qual peak. For the quant peak after I zero it and Quantitate Sample, there is no value for S/N.

2. When I export this data to Excel, the S/N infinity becomes 8 in Excel! This isn't much of a problem for peaks that have no signal but for some peaks that do have signal, the S/N is infinity. I assume this is when the noise is zero (although this doesn't really make sense - it should be undefined).

3. How is the S/N calculated? For some of my peaks the S/N seems a bit low but I have noticed that if I make a slight adjustment to the peak using the manual integration, the S/N will increase by a lot more than I would expect. For example, I have a qual peak with S/N 2.73. There is a tiny bit of baseline that is not flat (barely perceptible). When I hit the button to Drop Baseline the S/N is now suddenly 40.92! That seems like a huge jump when the amount of signal has barely changed. I see the same effect with quant peaks.

 

Thank you for your help!

 

masshunterquantitative analysis #S/N gcms signal to noise masshunter quantitative data analysis software

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