Chromatography Forum

Is octadecysilyl silica gel a C18 column? I need a 100 X4.6 mm, 3 um column. Any suggestions which brand I should go to.
Thanks in advance for your help.

Yes, octadecysilyl silica is C18. As for a brand or manufacturer, I have had great success with Phenomenex and Waters columns.

Other good brands I have used are the Zorbax line from Agilent and the Betasil line from Thermo-Hypersil-Keystone (Betasil are cheap too!). The previously mentioned brands are also good.

An other brand wich is very cheap and good quality is Kromasil packing from Eka Nobel, good mechanical property and average performance.
For exemple it cost about 200€ for a 150*4.6-5µm column packed by AIT (France).

Hi everyone,
I wonder, why noone asked about the aim of his method and the characteristica of his analyte.
So let me add a few points:
There are so many different types of column materials available.
Depending on your analyte you should consider, whether you need a fency new material (well endcapped, highly pure silica - for (for example) basic analytes or analytes that can build chelate complexes) or if an "old" one will do (less good endcapped or even without encapping, higher metal content...). Of course there are a lot more thoughts involved in choosing the right colunm: Use of MS, pH of eluents, pore size of the particles.... After you have chosen the right material, you can think about the supplier and the price...

The method that I’m going to use to test etomidate is from EP. It has the information for the column: 100 x 4.6mm, 3 um, octadecylsilyl silica gel. Anyway, thank you very much for all of your advices. I’ve just ordered one ODS-2 column from Waters.

If you are trying to match a compendial method, the best approach is to go back to the literature and find the original publication or monograph and find out what specific column packing was used. C18 columns vary tremendously in selectivity.

If the original column is not available, there is a database available (free evaluation) from Rheodyne that will let you find the closest selectivity match to that column. The program is called "Column Match"; you can download it from Rheodyne's web site (click on their link near the upper right of the screen here).

By way of "truth in advertising", I worked on that program when I was at Rheodyne.

Tom,
Thanks for your suggestions. For literature research, where should I go to find the original publication? Sorry, for asking this question. I hope you can help me again.
Thanks,

I'm not familiar with EP, but I believe the USP monographs include references.