The separation we are working on involves carboxylic acids, amines and a neutral column. Two amines and the neutral compound elute very late. However, the other compounds elute rather early. We incorporated 1-Octanesulfonate as an ion-pairing compound (anything shorter...the early eluting peaks interfere). This is when we had the idea to switch to a cyano column (from a c-8). We are not familiar with CN colums...is anyone else? Are they stable? what pH range? How is the reproducibility? etc. etc. etc.

The cyano columns are a little less stable than a C18 or C8, but for practical applications you should find no difference. Remember that the CN column is about C4 in chain length, so you will need to use a much weaker (more water) mobile phase for equivalent retention. pH range should be the same as other silica columns (2 < pH < 8 for most cases). Reproducibility, etc are also good. We routinely use CN when a C8 doesn't give the selectivity we want.

To help you source a CN column please consider visiting the www.chromatography.net website. There are over 80,000 columns searchable by PN#,
Tradename and physical criteria such as phase class (C18, C8, silica), pore size, USP Methods, etc... The column database is also integrated with a Chromatogram Library which is in the process of adding 20,000-30,000 chromatograms/applications linked to columns.

I searched for Cyano Columns and came up with
103 available columns. If you visit the site mentioned above, you can compare these columns side-by-side, which may help you find the correct one for your needs.

I hope this helps.

The good news on cyano columns is that you can benefit from real selectivity differences compared to C18 and C8. The bad news is that they're prone to voids. I've been running an ethanolamine analysis with HOAc/TEA buffer at pH 4.0 with success, so it certainly can be done. If you need to validate the method, I'd recommend trying columns from various manufacturers to get a feel for the range of retention times. We've tried Supelco, Phenomenex Develosil and Zorbax columns and got increasing retention in that order. Good luck - I hope it works for you!