Chromatography Forum

Hi All

I was wondering if anyone has any knowledge, or experience, with Charged Surface Hybrid (CSH) columns; specifically with respect to equilibration time.

As the name implies, these columns have some charge on the surface, and there are some benefits to this.

In their literature they actually claim faster equilibration with respect to changes in pH. But what I'm wondering about is the typical equilibration that happens at the end of a run, when the system is going from high organic back to low organic. I am suspecting that this type of equilibration may take longer with a CSH column, and so was wondering if anyone has had any similar observations.

Thanks very much, in advance.

Although I have no direct experience with such columns, we always considered equilibration to be more a function of "column volumes" of mobile phase than "time".

That said: we would use more equilibration volume when doing method development, and if that was correct/consistent/repeatable, only then would we investigate shortening that equilibration.

I believe the standard "rule" we go by is 10 column volumes, that should be more than enough. I recently ran a method on a BEH column where I had to extend the method 5 minutes for column equilibration because the injection immediately following the first injection started off at negative pA. I ran the exact same extended method on an equivalent CSH column and it worked the same- the subsequent injections were back at 0 for the baseline. Hope this helps, I am sure if there is a difference between column equilibration time it is likely insignificant.