Chromatography Forum

Hello all;
a Collegue of mine is trying to analyze 4-epianhidrotetracycline in capsules; following USP 30, but there is not good separation, at this moment I do not have the chromatographyc conditions at hand. but there is no good separation, there is a peak interfering
The coloumn is Lichrosorb RP -8, 25cm x 4 mm, but I wonder if there are other column useful?
I think Hybrid particle, Xbridge or sufire.



Thanks in advance.

Phenomenex Luna C8(2) columns are very good for tetracyclines (as well as for other amine containing compounds). Any column that has been manufactured with ultra high purity silica should work well. The tetracyclines, because of there chelating ability tend to have a strong interaction with metal contaminants in cheap columns giving poor peak shape. Do you know what mobile phase he is using?

I agree with the previous post that results are much better on modern high-purity silicas. Here is an application to look at: http://www.waters.com/WatersDivision/pd ... try167.pdf.

I did not check on the mobile phase used by the USP. One can also work with suitable mobile phases to prevent the accumulation of metal on the surface of a packing.

Silica based column tends to give bad peak tailing too, due to resiudal interaction. You can also try some columns specified by amine containing compounds, such as Allure Basix, a mix mode of C8 (C18?) and cation exchange.

Below is an application for oxytetracycline:

http://www.imtakt.com/TecInfo/TI216E.pdf

Another column is Gemini C6-Phenyl from Phenomenex, very good for aromtic amine.

Here is teracycline (blue line) and degardated mixture of other "ceclynes":

http://www.sielc.com/compound_285.html

It is performed on mixed-mode Primesep 200 column (combination of reverse phase and cation-exchnaage)

If the 30th edition hasn't changed from my 27th, the std USP method <226> for 4-epianhydrotetracycline is actually a 15mm x 170mm column of EDTA buffer on siliceous earth, followed by UV absorbance.

Maybe some monographs in the USP have HPLC methods, in which case it would be nice to know the details. As usual, there is a need to show equivalency if alternative methods are used.

Please keep having fun,

Bruce Hamilton

I agree with the post by sassman. You can find additional information relating to this application in the following link: http://www1.dionex.com/en-us/acclaim_li ... 29022.html