Why isn't the "discrimination factor" used more of

[Rob Burgess]

... as a means of evaluating the separation between adjacent peak pairs (especially where there is a vast difference in respective peak area / and or areas). It appears to be a simple and more elegant "chromatographic property" to calculate. Is it a historical thing I wonder?

Also would such a descriptor stand up to regulatory scrutiny and method listing? Finally are common chromatorgaphy data systems, such as Empower and Atlas capable of calculating a discrimination factor easily?

http://www.sepsci.com/chromforum/viewto ... ion+factor

[tom jupille]

Rob, I suspect that "a historical thing" is a big part of the answer.

I would argue that Rs is more "elegant" than discrimination factor in that it can more easily be related back to other parameters like k', α, and N (and perhaps the fact that it is harder to hand-calculate imbues Rs with a certain "mystique" that makes it more attractive ). The "ease of calculation" advantage of discrimination factor is offset to some extent by the fact that we rely on the data system to do that sort of thing, and I don't think it's a particularly easy calculation to do on the data system.

The "regulatory scrutiny" issue is a big one. Discrimination factor is documented in the literature (e.g., Uwe's book) so it could be used, but the fact that the FDA/ICH/USP define resolution and "suggest" its use as part of system suitability certainly makes it a safer choice (it's what auditors expect to see).

I don't know about the data systems. Off the top of my head, I doubt that discrimination factor is programmed in, but it should be possible to write a macro (or Excel spreadsheet for that matter) to calculate it. As I said earlier, though, while it's a nice, easy, intuitively appealing calculation to do by hand from a chromatogram, I don't think it's especially easy to do on the computer.