Accounting for system and solvent peaks when reporting impurites?

Empower2018

I have a related substances method which uses Area/CCalRef1[Area]*100 to calculate % Impurity for known and unknown impurities. However each sample has a certain number of "peaks" that are due to solvent or a system peak. I want to exclude these values when summing the total impurities and I cant find an efficient way to do this. If I name the peaks as Diluent, System etc then these peaks may not elute at the same time due to retention time shifts later on in the sample set (I run 5 batches per sample set). 

I tried to use the "Component Type" of Diluent or System Peak but again, this still requires you to name the peak, leading me to the same problem of retention time shifts. Does anyone have any suggestions on the best way to exclude these peaks without making it too complicated?

shaunwat

Use the peak label in the component editor of the processing method. Name the peaks what were you with, make the peak label "Blank" (as an example).

From your custom field standpoint:

... + EQ(Peak Label,"Blank")*-1*50,000 ...

What ever field is doing the above, sum it and use that summation to report your total.

Empower2018

Thanks Shaunwat that would do the trick I hope. 

HeatherLongden

or reversely... use some peak label (many users historically used a CConst field =1) to label the peaks you ARE interested in. Then have your summary calculation only use THOSE peaks. (That is what the Impurity Processing functionality does now automatically) Before we had all the new options the admin would set up Area x CConst1 as the response field.

dbenach

I would like to do the same thing that Empower 2018 mentioned at the beginning. I have a Custom Field 
VCArea =
Time Corr. Area*LTD*60     (Note: LTD is a keyboard entry Real Custom Field)
Peak, Real, Search Order - Result Set Only, Sample and Peak Type-All

If I create a Custom Field called AreaAdj = SUM(VCArea)+EQ(Peak Label, "Blank")*-1*50000
Peak, Real, Search Order - Result Set Only, Sample and Peak Type-All

I get an error stating that "Only Distribution, Chrom, Injection and Vial fields can be used with SUM, MIN, MAX, or AVE when creating PEAK Custom Field". If I change AreaAdj to a Result Custom Field, I get an error that says "A peak/component field can't be used with Sum, Min, Max, or AVE".

Did I not understand what Shaunwat posted?

Empower2019

Go back to your first CF and add the condition there:  (TimeCorr*Area*LTD*60)+EQ(Peak Label,"Blank")*-1*50000 and make sure to tick All or Nothing in the formula editor or else it wont work. That formula will only return answers for peaks that dont have a Blank label.
Then you can create another CF to sum the first CF. Result Real CF with formula SUM(VCArea) will sum all the cf values per injection for all peaks or if you want a combined value over multiple injections per peak you can type something like U%.%..SUM(VCArea)

dbenach

That works! Thank you.