mixed mode (RP/IEX) HPLC columns

[gregg]

I've recently been reading quite a bit about mixed mode HPLC columns, which use a mixed mode RP/IEX type stationay phase to analyze peptides and small proteins. I've seen promising results in my lab, but wonder about how robust and reproducible these columns when they are used extensively in a GMP environment. Comments appreciated.
Thank you.

[Mattias]

No problem I would say.

We have just implemented a quick assay method for a drug and its counterion in just 5 minutes, which normally would require two methods.

It has been approved and also transferred to external labs, without any problems.

[Nalizer]

Mattias,
What column do you use? Have you tried different lots of mixed-mode columns?
We validated four methods on mixed mode columns. Two of them were transferred to manufacturing sites.

[Mattias]

That method uses a Primesep D column. I cannot recall how many batches columns we used in the validation but it was at least three.

However, the separation was very simple and we were only interested in those two peaks.

[Nalizer]

We have a method on Primesep D, too (small acidic molecule). Also we have a good method for protein (4 kD) on Promix MP column. Both columns work pretty good for our applications. We tried 3 different lots for each method; reproducibility was within our limits