Chromatography Forum

Hi,

I’m setting up custom fields in empower 3 for an impurities report template. I need to subtract certain known peak areas from the total area for the individual impurity % area/area calculations.

For example, in a sample containing BHT I need to calculate the % area of each impurity against the total area of all peaks in the sample except BHT. At most I would have to subtract two peak areas.

I have tried using CCompref for this:
Adjusted_Total_Area = Total Area-CCompref1[Area]
Adjusted_Percent_Area = (Area/Adjusted_Total_Area)*100

Currently the Adjusted_Total_Area custom field just calculates the total area without subtracting anything. Also, I assume doing it this way would mean I'd have to label every impurity peak and assign CComprefs individually to each in the processing method?

Does anyone know a way of making this work, either in a similar way or completely differently?

Thanks for any help

Name and exclude the unwanted peaks. By naming them sys_1, sys_2 etc. you can get them all with a sys_* exclusion.