Polymer-based SEC columns

[HPLC_chainik]

I routinely run SEC samples on a silica gel-based high efficiency SEC column and was happy with it until I encountered non-specific interactions between my analyte and the stationary phase in one series of my samples. The analyte was a polymeric nanoparticle with a hydrophobic small molecule encapsulated in it. I ran it in an aqueous buffer and expected to see a nice peak corresponding to the size of the polymer particle. To my surprise, the SEC phase acted more like a reverse phase retaining the small molecule and letting it elute way beyond the limit of the small molecules for this SEC column. The peak attributable to the particle was there, but it was an empty particle. Adding 10% methanol moved the peak of the small molecule to an earlier time, but still way beyond the limit for small molecules, adding a piece of evidence to support my hypothesis. Tech support for the column confirmed that if I have a very hydrophobic molecule, it can be retained non-specifically on the silica-based stationary phase.
I noticed that there are polymer-based SEC columns available on the market. Can anyone recommend a good brand? Also, do you know if they are much more hydrophilic than silica-based ones? I have good relationship with people at the company which sold me the column I am currently using, but, apparently, they are not making polymer-based columns and did not want to comment on them.
Here is what I found so far: http://www.pss-polymer.com/products/col ... c/suprema/. But I do not know the brand and am not comfortable about choosing the column without knowing enough about the phases.

[Gerhard Kratz]

Please contact Andrew Alpert at aalpert@polylc.com. PolyLC is producing polymer based SEC columns and Andy can explain it in detail why you see that on your column. Good luck.

[Andy Alpert]

Thanks, Gerhard. Actually our columns are silica-based with a polymeric coating.

Most SEC columns that are sold for life science applications were designed for use with proteins. When such columns are used for small solutes then a disturbing trend becomes evident. Compounds with aromatic rings (tyrosine; phenylalanine; aromatic drugs) are actively retained, with the effect being worst with the most highly crosslinked carbohydrate-based materials (e.g., Superdex Peptide, Sephadex G-25, etc.). Some SEC materials based on more conventional polymers exhibit this trend too. We went out of our way to demonstrate that this is not the case with our silica-based SEC column materials, cf. this link to my book chapter on the subject: http://www.polylc.com/downloads/SEC_boo ... r_ver1.pdf

So: Try a PolyHYDROXYETHYL A column. If it doesn't work on that, then it won't work on any SEC column.

[HPLC_chainik]

Thanks, Gerhard. Actually our columns are silica-based with a polymeric coating.

Most SEC columns that are sold for life science applications were designed for use with proteins. When such columns are used for small solutes then a disturbing trend becomes evident. Compounds with aromatic rings (tyrosine; phenylalanine; aromatic drugs) are actively retained, with the effect being worst with the most highly crosslinked carbohydrate-based materials (e.g., Superdex Peptide, Sephadex G-25, etc.). Some SEC materials based on more conventional polymers exhibit this trend too. We went out of our way to demonstrate that this is not the case with our silica-based SEC column materials, cf. this link to my book chapter on the subject: http://www.polylc.com/downloads/SEC_boo ... r_ver1.pdf

So: Try a PolyHYDROXYETHYL A column. If it doesn't work on that, then it won't work on any SEC column.

I love this forum! You ask an amateurish question, and somebody responds with a book chapter on the subject written by the correspondent.