UPLC method transfer: validation?

[A.Nonymous]

Hi,

we are currently using some USP methods for raw materials.
As stated we use a L1 (C18) column with the prescribed mobile phase, solutions, .....
WHen we fullfill the method requirements (eg resolution, plate count, %RSD on 6 injections, ...), we can use the method to analyze our raw materials without validating the method entirely.

If we want to change to Waters UPLC, we can still use a C18 column, but it will be much shorter, and a with a smaller internal diameter.
We can use the Waters calculater to transfer the method to UPLC, and the results are amazing, increased resolution with decreased run time.

But what about the validation of the method?
As UPLC is based on pure chromatographic principles, one can easy understand that if you use 1.7µm particles, you have more plates/meter as with 5-10µm as stated in the monograph. For the use of shorter columns, you have to adjust your gradient, based on known calculations. For the use of smaller internal diameters, you have to adjust your gradient again and also your flow rate to get the same lineair velocity.

From my point of view, the only thing which is really changing is the column chemistry, the other adjustments can be calculated.
The change of column chemistry isn't that bad, because the monograph stated an L1 packed column, which can be hundreds of packed columns.

So, if we full fill the method requirements for resolution, plate count, %RSD, ... Do we have to re-validate the whole method for UPLC?
Or just a comparison between the methods by injecting the same samples on HPLC and UPLC and showing equivalency?

Thanks for your help

[Uwe Neue]

The USP has a range of criteria that tell you, how much of a change is allowed without revalidation. I do not have them in front of me at the moment, but they specify changes in flow rate, column length, particle size etc. that one can do within a method.

How well they apply to a transfer of a method from classical HPLC to UPLC needs to be examined in detail. I recall for example that a switch in column diameter was possible such that one could go from a 4.6 mm i.d. column to a 3 mm i.d. column, but not directly to a 2 mm i.d. column. But from a 3 mm i.d. column, one then could go to a 2.1 mm i.d. column.

While these rules were intended to give the user some flexibility, they are not in line with basic chromatographic principles. I can get the exact same separation going from a 30 cm 10 micron column to a 15 cm 5 micron column to a 5 cm 1.7 micron column, if I have the same column chemistry available and change the flow rate accordingly. The only thing that would change in this case is the time frame. In this example, it would be a 36-fold reduction in analysis time.

[A.Nonymous]

Uwe,

Neither do I have the USP on my desk for the moment, but I found some guidelines on the internet:
column length: -50% to +100%
column ID: ±25%
flow rate: ±50%
particle size: can be reduced by 50%

So if I have a method: 250x4.6mm 5µm column, flow rate 1.0ml/min,
I can't get a method with a column of 50 x 2.1mm 1.7µm without entirely revalidate the method. Although the separation would be not effected if one can use the same chemistry.

Maybe there are some other who have experience with the regulatory instances and who have some ideas to get away with this?

[Alex Buske]

I think these values are specified in the EP, I am not sure about the USP.
Changing from HPLC to UPLC certainly violates the mentioned limits, so some validation would be necessary. I assume you would even like to change the injection volume.
So selectivity, linearity, accuracy (best compared to the old method), precision and LOD/LOQ should be tested. Stability of solutions I would consider not to be important. On the other hand it makes it easier to have everything in one report.

Alex