Chromatography Forum

Hi all,
I am using empower 3 Software and have a question concerning processing:
- sample: Main compound (>>LOQ) + impurities
- external Standard: Main compound (linear calibration)
- I already determined the RRF values for impurities vs. main compound in Validation experiments.

How do I have to set up my processing method so that I can calculate the amount of the impurities using the external Standard and the RRF values?

I can not use the main compund in the sample as internal Standard because the concentration is >> LOQ. I have to use the external calibration. I tried out several Things but I could not manage it. My understanding of Empower ist OK I think but I am not a specialist

Would really be great if anyone can give me good tip.
Thanks a lot

Use a low level standard?

Its complex but you could use a custom field to report your impurities and use the mean bracketing standards and everything else used in your reporting formula in this custom field eg Percent Imp % w/w = Area/ Mean Area Bracketing Std x Weight of sample x Factor x RRF x 100 or something similar.

Hi all,

thanks for your replies.

OK so I will try out with the custom field idea - I thought there might be an Empower solution for that Topic available in Standard process methods.

burc, did u manage to calculate impurities this way? i have the same question tell me how u solved it please.