Chromatography Forum

The way I understand USP <621> (which isn't saying much), is that when one uses a 150mm length HPLC column, that using a 20mm guard column of the same packing, or not using such a guard column, falls into the +/- in column length tweaking that does not require a re-validation. Agree?

Also, if I use a stainless steel or similar guard frit at the column inlet instead of the stated guard column, would that also fall into the realm of tweaking and not require re-validation?

I guess I'm not as detail-oriented as my QA paper punchers who can't spell "HPLC", and we're re-validating a bunch of test methods now that avoid acetonitrile, and I wondered what others felt about whether stuff like this requres re-validation. I'm not asking about the technical opinions of yes/no for guard columns.

I don't think a pre-column filter would require a method-revalidation. Simply because it has no separation properties and is just a filter. It would require a method change.

Adding a guard column will effect the separation.

FDA does require "The rational for the use of precolumns and/or guard columns should be provided and justified." Analytical Procedures and Methods Validation Draft Guidance August 2000, page 22.

The conservative approach (and typically QAs) would be to re-validate or not use a guard column.