MAX custom field query

ciaracarroll

I run an impurities method at 2λ (230 and 280nm). I am trying to pull the maximum area counts of peaks and sum together to get total impurities independent of the wavelength. So if peak A area is greater at 280nm it is used and if peak B area is greater at 230nm it is used to calculate total impurities. Is there a way to do this in Empower?

Empower2019

Two custom fields will do this. First, create 2 derived channels in the method set used to acquire data and call each channel something very simple like 230 and 280. If its a pda method, select single wavelength, add the wavelength (230 and 280) then name the derived channels as above. If they are 2 channels in a TUV method, get the exact channel names for both as you need this for cf formula. Look at channels tab in project and the name appears here. Its usually ChA and ChB.

First cf is a peak, real cf. Result set first and set sample type to unknowns only as i presume your impurity samples are unknowns. The formula:
GT(%.%.280(Area),%.%.230(Area))*%.%.280(Area)+GT(%.%.230(Area),%.%.280(Area))*%.%.230(Area)

Call this cf MaxArea_twochannels and ensure you have some label for each sample example U01 U02 U3 etc. A label must be present.

Second cf result,real cf. Search order result set first again unknowns only. Simple formula:

SUM(MaxArea_twochannels) call this Sum_impurities and make sure to add the function Summarize Custom Fields (and corresponding Processing on that row set to Normal) as last line of sample set where you are running these samples.

The 1st cf will evaluate each peak area in both channels and only display the max area out of the 2 channels. Peak area will need to be present in the 2 channels or else this cf will just crash out.The 2nd cf adds up all these max values and displays the sum, which can be found in the Result icon when your process a sample set to generate a result set. You can pull this value into a report method.