Modern C18 Stationary Phases - Phenolic in Tea Samples

[Renato]

Hi all!
I going to purchase about 15 columns to start a study in Tea samples Catequins, Flavonoids and Teaflavins.
Most of the Methods in the literature are C18 Gradient Water/0.1%acid and ACN/0.1% acid.
What are your suggestion for most modern Stationary Phases available: endcapped? 3um or less ? Can I use such as silanol activity as a parameter for the choice? Embebed Groups?
The objective of the study is test the most modern columns available and compare the Chromatographic parameters related to the Polyphenols.
Thanks,
Renato

[Bryan Evans]

Hi Renato -

Sounds interesting! I think 3um columns would be the way to go -
you get excellent separation and they can be used on any HPLC system.

We have 2 types of C18 columns - Cadenza CD-C18 and Unison UK-C18.
The nice thing about these columns is they are 3um columns that
also come in 25 cm length (50,000 plate column). People separating these compounds may need all the plates they can get!

http://www.imtakt.com/TecInfo/TI144E.pdf
http://www.imtakt.com/TecInfo/TI145E.pdf

Please feel free to contact me should you need further assistance, thank you.

[Uwe Neue]

This is an area where it is good to use a classical C18 and one with an embedded polar group. For compounds with phenol functions, you can get pretty drastic selectivity differences between a C18 and a C18 with an embedded polar group at acidic pH, pH 2.5 or 3, best with a phosphate buffer. You will be best off using EPG columns that are prepared in a single step. I recommend XBridge RP18 (with the embedded polar group) and XBridge C18 (normal C18) as your columns of choice.

[Renato]

Uwe,
Symmetry shield should me a good option for EPG?
Should I use for this Phenolic compound type B silica only or maybe should I test with Type A? Do you expect some Silanol Effect?
Thanks
Renato

[Uwe Neue]

In my recent tests with a large set of compounds, I did not see a specific silanol effect for phenols with classical C8- and C18-type bonded phases. On the other hand, among the over 15 different columns that we tested, there was not a single one of the old type A. My conclusion: I do not know for sure that old silanol columns do not do anything specific for phenols. I personally would not go for such a column, but I could be wrong.

[Bryan Evans]

Hi Renato -

Here are some more flavanoids applications
using our Cadenza CD-C18 column:

http://www.imtakt.com/TecInfo/TI279E.pdf
http://www.imtakt.com/TecInfo/TI280E.pdf

Please feel free to contact me if you are interested
in using this column for your research - thank you.

[juddc]

You might obtain some interesting selectivity with phenyl and phenyl-hexyl RP columns along with selected C18's with or w/o embedded polar groups.

Just a thought...