Chromatography Forum

Hi

I would like to know what is “Double End Cappedâ€

"Double end-capping" means "end-cap twice". The objective is to minimize the amount of un-reacted silanol groups on the silica surface after bonding step. If one end-capping can provide maximum surface coverage, I don't see the need of doing it twice. Also, it is possible some manufacturers use two different end-capping reagents in sequential steps. I don't have comparison data on double end-capping vs. just end-capping columns though.

I agree with Xiadong Liu that this may refer to a sequential procedure with 2 different reagents.

Unless a serious independent researcher studies this problem in a systematic way, you will never get a real answer to your question. Therefore, I would regard double endcapping as a marketing statement until it is proved otherwise by independent research.

There is no point in comparing one manufacturer's single endcapped column with another's double endcapped column because you would need to study the same base silica taken through the single and the double endcapped procedures. Even then, it is possible that double endcapping might give good results on one manufacturer silica but not on another.

I am not saying that the double endcapped column from manufacturer X may not be better than a single endcapped column from manufacturer Y. Just try the columns as use the one that gives you the best results. But you will not get to the bottom of the problem as to WHY this difference occurs, or whether it is attributable to the double endcapping or not.

I agree with the last statement. You have to be careful about marketing speak. I believe there are columns around that have "triple endcapping". I am waiting for an ad on "quadruple endcapping"...

One could argue that if one does not get it right the first time round, one has to do it over and over again...