Weird results when asking Peak to peak noise calculation on EIC GCMS openlab CDS


I have tried to perform peak to peak noise calculation on a result set that contains 65 target compound. 

Usually it when ok but some of the compounds have weird results. 

First, some have no result at all. 

Some have way to high S/N values. 

I don't know what's wrong. Can it be a software bug? 

thank you for your help

  • Hello,

    I would guess there is some issue with the blank you are using in that time segment. You can display the noise for that region in the results to see if the value is zero or extremely low. You will probably need to open a support ticket either with the customer service number for your region or informatics support if you are a client server customer. Agilent will need to look at the results that exhibit the issue and we cannot share those on the community site. 

    Marty Adams

  • I checked the noise and for the cyclohexane peak and you're right, the noise is zéro. How can I have zero as noise?

    For the other compound that give no result at all, I have no value at the noise column. 

    Have you ever seen that in the past? 

  • Hello,

    Without being able to see the data I cannot say for sure, but I would think there is an issue with the blank. It looks like you extracted a big enough time window, so the software should have the required data points of 20*W50 for the calculation of noise from the blank. If you want to investigate the problem further, open a support ticket with your local region or informatics support if you have a client server system. 


  • Hello,

    I took a look at this again and you may want to avoid the time range extraction if you are doing automatic noise calculation. I have to confirm this is working as intended but it seems the EIC on the blank is not extracted when there are no peaks found in the time window. This will lead to no value for the noise being calculated. You might look at your blank and see if there is EIC extracted for 97 around the 6.296 RT. Also, if the blank is clean enough in the noise window for the peak you can get some odd calculations including 0 with a SN of infinity. I think this is because the GC-MS will record 0 for ions when not detected the so it is possible in some cases for that automatic window to calculate low values or even 0 if all the data points are 0. 


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