Bioequivalence and Bioavailability Forum

Dear Alhas,

❝ If a predose (without IS) shows a very high concentaration

You can't calculate a concentration in a sample without IS, by comparison to a standard curve with IS ! Of course if you have a slight carry-over, or something your chromatographic software identifies as an IS peak, the software will calculate a concentration. But it is meaningless and it should be disregarded. All you can do with this sample is check that you have no interference at the retention time of your IS, and compare the analyte peak area to that of the first calibration sample.

Regards
Ohlbe