Bioequivalence and Bioavailability Forum

Hi Ohlbe and all,

❝ If you feel there is still more to discuss, Bioanalysis has just published a whole issue on this topic.

For sure, I am going to look into this with great interest - thanks.
Am OoO at the moment so can't look everything up, do you know if any of these or other publications deal with between-batch variation in IS response?

I am asking because I am seeing a tendency for CROs to define within-batch criteria for IS responses and trends, but I am also seeing at certain CROs how the IS response can vary enormously between runs. At other CROs the IS may be rock solid between runs, and it is of course somewhat equipment and analyte-dependent and factors like column age play a role. The phenomenon is really striking in some cases, but you will only see it if you look for it. I do not have a reference to discuss it numerically and I did not see this matter discussed on the forum here. In some cases I can almost predict the method is about to go out of whack, but it is always the same "But this run passes so there is no issue..."

I am looking for something that is a little better than the bare "But if the run passes...", "perhaps it is the ion source blah" and which has the quantitative aspect in it.

Am in dialogue with a few sponsors to see if we can publish on this matter if noone else has done it. But few sponsors seem willing to make public stories about how enormous the between batch IS response can be, - perhaps because it may reflect badly on their products?