How to deduct blank peak area from sample (or standard) peak area

Question

Dear All!

A customer would like to do the following (I already advised them about blank subtraction but it is not what they want):

What the customer has already done:

CC1: to get the blank area(s)

cc_BlankArea

Average("Compound_Area", AllMatchingPeaksAndGroups(MatchOption.Compound,CurrentSequence.AllInjectionsOfType(SampleType.Blank)))

CC2: to deduct if there is a peak with a larger area in the sample (or standard) than in the blank):

cc_CorrByBlank

if(Compound_Area>=val(cc_BlankArea),Compound_Area-val(cc_BlankArea),0)

This works only if the peak is appearing (integrated) in the blank. If it is not then the CC "fails", does not calculate, there is nothing to deduct. Thats why they tried to use the "val" function unfortunatly with no success.

Do you have any ideas to handle this situation when there is no peak in the blank?

Thank you very much in advance,

Peter

ir_nerd · Accepted Answer

Hi Peter, Yes, it's not the best solution as we do have the blank subtraction for this. Custom Calculator in OpenLab CDS v2.x is only dealing with what the CDS provides (i.e integrated peaks), there would not be any way to do what your customer wants to do if there is no peak in the blank. As dnprulz did, you would need tto check there is a blank peak corresponding to your compound. One way to insure that is to use a different processing method for blank and other samples. You can use saved manual integration in the method used for blank, and usual integration parameters for the other samples. But you must be sure that both processing method have the custom calculation that you use. Regards, Pierre

How to deduct blank peak area from sample (or standard) peak area

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