Benzoyl Peroxides and C8 and C18 stationary phases

[luischinch]

Did anyone had any kind of interaction between Benzoyl Peroxide flushing as a sample into C8 or C18 Stationary Phases? I mean that interaction collapses these phases?

[Consumer Products Guy]

I've only done the assay a few times, don't remember any HPLC issues. I think the only "issue" was obtaining a decent standard as the BP typically has high water content.

USP is about $300 for "everything", and typically only provides a miniscule amount.

[luischinch]

My product is a gel with 0.1% Adapalene and 3.0% of Benzoyl Peroxide.
I´ve observed this problem ending one month validation for both actives, during this period I´ve done lots of sample inyection for both systems. And for adapalene valoration the concentration of Benzoyl Peroxide (BP) is about 0.3 mg/ml an in the sample of BP valoration is 0.03 mg/ml.
Both assays were preformed in the same column (Waters Symmetry C18 150x4.6 mm 5um) with different chromatographics systems, and the column flushing 0.3 mg/ml colapses more rapidly than the other.
I´ve a lot of experience with adapalane in the same gel base and it didn´t present a problem. The only addition of BP generate the problem.
I read that BP is used in the initial polimerization when stationery phase of HPLC columns is produced.

[tom jupille]

As far as I know, benzoyl peroxide is not used to initiate any polymerization of C18 or C8 bonded phase packings, for the simple reason that no polymerization is involved. Most commonly, a reactive silane is used to attach the stationary phase to the silica support. BP *is* used as an initiator for polystyrene-divinylbenzene resins, but those are relatively uncommon for reversed phase work.

Which brings me to the next question: what do you mean by "collapse"? What symptoms/problems areyou seeing?