Does anyone have experiences with the so-called “aqua columns“?
I’m just testing an ODS-AQ from YMC, because I always have problems with the analysis of patulin (a mycotoxin). The problem: We have to separate patulin (a trace component) from 5-hydroxymethyl-2-furaldehyde (a major component) in apple-juice extracts. On a Waters NovaPak C18 300 x 3,9 mm, patulin has a retention time of 13,3 min, the aldehyde one of 12,2 min (water + acetonitrile = 97 + 3; 0,8 mL/min). At the end of the run, we have a gradient up to 90% acetonitrile to clean the column from other major components of the juice (although SPE-cleaning of the juice extracts, but only UV-detection). This system is not very stable (to little organic modifier for a NovaPak?), from time to time the retention times differ between several runs. And the run time is too long (35 min) – waiting for equilibration after the gradient.
That’s why I wanted to try an “aqua column” (ODS-AQ from YMC). And now I have found an interesting remark in their information sheet for the column: “To prolonging the column lifetime we suggest using at least 20 % of organic modifier”. What does this ist mean? Is ist “dangerous” to use this column with very high percentages of water (up to 100%) – resulting in short lifetime, high costs…
Is this a common problem of such columns – high stability at pure water conditions, but short lifetime? Or is it only a special one of this column? And what “aqua column” on the market is the “best”?
And back to our problem: Is it a good idea to try an “aqua column” like ODS-AQ or could we have more success with trying an other conventional column?

Thank you!

Aqua columns are specially designed not to collapse when up to 100% aqueous phase is used. Bonded phase is electrostatically shielded by incorporating polar groups into the bonded alkylsilane. Somebody around me is running some “Aqua” nonstop for a few months without problems.

I must tell you up front that I am prejudiced - very prejudiced. I prefer, if the manufacturer tells you what the packing is that you are dealing with. Then you can make intelligent decisions yourself on how to use it in the best way.
There are several types of the "aqua" things on the market. In my opinion, there is unknown voodoo, and then there are those with an embedded polar group. Among the latter, you have Waters SymmetryShield, Supelco's Discovery RP Amide C16 and Keystone's Prism and Spectrum (although Keystone doesn't tell you either, what the stuff is). These phases can be run in 100% water, give you good peak shape, and are prepared with procedures without any secret magic. Contact me if you want more info.

Thank you, Mr. Neue. I would really appreciate to get some more information dealing with this topic from you. Please find my e-mail address at the top.

I've been using YMC AQ columns for some time now for polar compounds. They have given me very good performance as far as retention and peak shape. One typical mobile phase would be 5% ACN in water with no buffer or organic modifier. Of course this would be dictated by the compound. A colleague of mine prefers to use E.S. Ind. Aquasep; claims the columns are more stable.

However, I do prefer a vendor let me know what the column chemistry is. For future method development, if I have several column vendors knocking on my door trying to sell me columns, I will consider trying columns if I know what the bonded phase is (including any polar groups). For those that tell me their bonded phase is "proprietary", and I don't know what I'm working with, I'll politely smile, listen, and then walk them to the door. Sorry guys. It's just the way I feel. I prefer to know what I am working with and understand its mechanism. I wonder what the Regulatory "God's " would have to say on this?

I have used the AQ type columns, including the YMC, for the analysis of aliphatic acids(C2 and greater)since they were first intorduced. the columns are typically run in 100% water with phosphoric acid. I have never experienced any problem with column life under these conditions, including the YMC columns.

My Preferred column is the ES Industries Aquasep. It is the most retentive of the lot, likely as a result of its very high surface area. If the problem is getting retention for poorly retained compounds, this column would be a good place to start.

For a summary of the properties of AQ columns see, J. Chromatogra, 868 (1999)42.

For the record, the salesperson "knocking at the door" ofter has not a clue what the bonding chemistry of a column may be. I have had good success asking higher up. I have had good success getting detailed column information from ES Industries (ask for Mat)& Keystone and less success with the larger companies, especially Metachem.