Chromatography Forum

My tablet contain PVP and HPMC, about 10% respectively. Unlucky, my pre-column was blocked often, nearly everyday. After that, I have been told that PVP will interact with C18. So, I think this accident may be universal. Any related experience or suggestion?

If you have switching valve (stand alone or part of your HPLC system) you can trap excipients on the guard and wash the guard during analysis. We used this approach to analyze melamine in milk without any sample prep and for analysis of active ingredients in complex mixture (gum, PVP and bunch of other excipients). The approach, if carefully designed allows you to analyze very complex composition containing polymers, proteins, excipients without any SPE or sample prep work:

http://www.sielc.com/pdf/SIELC_September_2004.pdf


If you provide me with the list of compounds in your mixture I can advice you on what column/guard combination to use and what mobile phase will give you desired result.

Another option is to try Cadenza HS-C18 (hydrophobic / hydrophillic hybrid ODS phase).
This is assuming the excipients are water soluble and have a mwt > 30kDa.

Below are applications for exclusion of excipients:

Disopyramide in PVP Aqueous Solution: http://www.imtaktusa.com/site_media/fil ... TI395E.pdf
Lidocaine in CMC-Na Aqueous Solution: http://www.imtaktusa.com/site_media/fil ... TI390E.pdf

(note: these methods do not require switching valves)

PVP is a polymer with a wide range of MW (2.5K to 2M). From my experience not all PVP elutes from the column, part of it will get stuck on the column and change selectivity and peak shape for analytes. Usual recovery of PVP from the column is 80-98% (depending on what source of PVP is used). So there is always a chance that column will deteriorate without sample prep or other alternative technique for removal of PVP from the column. Column manufacturers like when people don't do sample prep and kill columns with excipients....

In the data I posted (TI395), 1.5ug of PVP-K30 is injected onto Cadenza HS-C18 (3um).
This is a special ODS phase; C18 + hydrophillic ligands. PVP-K30 is excluded via the hydrophillic ligands.
Scientists using Cadenza HS-C18 under these conditions can expect much improved column lifetime over conventional ODS.

(A brief online search suggested the ave mwt. of PVP-K30 is between 40 - 60kDa, dependent upon the manufacturer)

How about other excipients? Is there a list about interactions between excipient and stationary phase?