Chromatography Forum

I have a project for adjusting some USP methods from "HPLC" to "UHPLC", i.e. smaller particle size, shorter columns, faster separation. I thought I would just check the latest USP Chapter 621 guidelines (released August 1, 2014) as, like many others, I have been waiting for the updates that would allow more flexibility in choice of column dimensions and particle size.
I was surprised to see the statement that says: "For gradient separations, changes in length, column inner diameter and particle size are not allowed".
This means we can only change isocratic methods and yet I know from experience that gradient methods can be successfully and easily converted when the gradient steepness based on column volumes is kept the same for each gradient step and making an allowance for difference in delay volumes between systems.
Has anyone else got views or comments on this?

Unfortunately I'm afraid your interpretation is correct - according to USP no transfer of gradient methods to UHPLC is allowed.
In Ph. Eur. it's just a bit different - it's allowed to change column length and diameter within certain limits, but you're not allowed to change the gradient time points or particle size, so again, no transfer to UHPLC possible.
That's the trouble in Pharma - we're supposed to use state of the art technology and methods, but we're not allowed to do so It just takes a lot of time for new technologies to be officially adopted in the regulated environments.

Time for the USP to get into the 1990s.