Area reject on individual chromatograms?

Compound A elutes in each chromatogram and i want to report the peak areas in each chromatogram that are greater than the peak area of Compound A in each chromatogram. As the area of Compound A varies in each chromatogram i can't use the area reject in the processing method as this applies globally to all chromatograms.

Can you help find a way to do this? I am using OpenLab 2.3.


  • To update - i have found a way to report only peaks which are greater than Compound A on an individual chromatogram basis. This involved linking and processing the results set with the following CC to find the peak area of Compound A in each specific injection:

    CurrentInjection.SignalByName(Signal_Name).PeakOrGroupByName("Compound A").Peak_Area .  

    and then calling this CC as the Value in the Filtering properties of a table using Peak_Area as Value and > as Operation. To get the CC into the Value field i selected Compound, Custom Calculation Results then the identifier that i gave the CC in the CC file. This table was repeated for each sample.

    This was achieved by trial and error really but thought it worth sharing. If there is any other way of achieving this output without using a CC i would be keen to know. 


  • you could have an invisible table, filtered to samples (sample type) and compound A. Then in the column for area, save the result as a variable with unique key value = sample name.
    In the samples table where you report you can then compare a peak against the variable that you just created, which will automatically be different for each sample.

    let me know if i have to elaborate on it

  • Hi dwaelsve

    Thanks for you reply. The part i'm having trouble with is how to compare the peak results to the variable.  i have tried typing it in as expression using the variable name and unique key i created but i get errors. I cant call the variable directly in Filtering. Please can you elaborate? 

  • Hi  Camelia

    When you press expression in de filtering, you can go to the variables collapsable thingie.

    does it work when you select it there? (picture is of a variable that is keyed to sample name, so it should look similar)

  • Hi dwaelsve,

    There is no variables field for me to select when i press expression in filtering. I am using Openlab 2.5

  • did u declare the variable before the group/table where u want to use it?

    If i select my very first table my view is exactly the same.

  • Yes, the first table where i saved the Compound A area as a variable with unique key is above the 2nd table where i am trying to report the results. Very odd!

  • Hi dwaelsve,

    Thanks very much for your help. I have used the approach you have suggested with the variable and unique key on a different system and it works perfectly. Using this approach is the preferred option to the CC. Why it is not working on the system i am currently using is another issue!

    Thanks again.

  • Hello,

    Be aware that using stored IR variable as filters is not possible in older revision of the software. In some versions where the variable are not displayed you can use a custom expression to access them. Chemstation prior to C.01.10 and early versions of the CDS 2.x software variables cannot be used in filter expressions at all, do to issue with the rendering engine. 

    Marty Adams

  • Hi Marty

    I am currently using Openlab 2.3 so i guess it is not possible with this revision to use stored IR variable as filters? 

    I am interested to learn how to use a custom expression to access the stored variable - are you be able to provide more information on this please?

Was this helpful?