Chromatography Forum

Hi,

Could anyone provide information on RP column equivalency? I know there is a table somewhere on the world wide web but havent found it. The column I want to match is Lichrosorb RP 18 250 x 4 mm, 5um.

Thanks in advance.

O

<BUMP>!

I too am looking for some information on general practices surrounding column equivalence. Is there a guideline, or document out there with general details? We have a method with a problematic column and have done some work to show that we can get similar chromatography on the alternative column, but what tests or guidelines would you use in a GMP environment to make an "iron-clad" determination that you alternative column is equivalent (i.e. pass the the "red face" during a regulatory inspection.

Any input would be greatly appreciated.

...A colleague eventually found the column equivalency table on USP (I knew it was out there somewhere)

http://www.usp.org/USPNF/columns.html

If I can provide any assistance....

You're looking for USP L1 - basically ODS (c18) column, 3-10u particle size...

Most manufacturers have a listing of their columns, i.e Waters, HP-Agilent, Supelco, etc...

For example:
http://www.phenomenex.com/Phen/Products/HPLCUsp.asp

Hope this helps...
Ktown

The following reference explains the theory behind the PQRI column equivalency guide at USP:
Journal of Chromatography A Volume 1057, Issues 1-2, 19 November 2004, Pages 49-57.
Personally, this theory is the most satisfying approach to the subject I have seen yet.

My question in particular was centered around how does one go about proving that the columns are equivalent. I know you should at least show comparable specificity and precision (i.e. repeatability and intermediate precision), and some how show that the chromatographic profile of your sample matirx is similar on the new column. I was curious as to common 9and best) practice when showing column equivalence. I will look at the journal articles and links posted above.

EDIT: Good stuff thanks for sharing those links.

One could make the argument that proving equivalence is subjective, but I feel taking the conservative route and showing some comparison work up front, you can reduce the chances of surprises and headaches down the road.

Now that we better understand your question... The first obvious thing is can you validate the method using the new column? The method authors should have included all the critical requirements, such as resolution, symmetry, linearity, etc. There may be mention of relative retention times, see if those are guides or specifications. The more tricky part has to do with interferences and artifacts. If an interference is differently resolved from a peak of interest than the original column, you could have issues with quantification when the real samples are run and difficulty comparing to historical data. The more baffling question is what happens if you resolve a peak that was not found using the original column. The honest response is to tell your boss and the QA manager and let them make the decision that they are paid to make.

Don't be surprised if "apparently" equivalent columns throws up the odd surprise such as differences in Rs or relative retention times (RRT). I very much doubt you could find 2 columns with a 100% match for all of your chromatography performance parameters (especially for challenging gradient impurity assays!).

The only advice I would give is to choose your critical method parameters and try to get equivalence for these before worrying too much about the other parameters.