Three columns - question for Matthias (and others)

[KM-USA]

I developed the method and validated it with three different batches of ...columns.

Question: we used to also use three different batches of columns for our validations. But our QA says it can't find any written requirement for this (but agrees it to be a good practice), so now we don't specify more than one column be used.

So please share your guidance for using three columns, or more than one column, thanks.

[prepcolumn]

QA always desires everything as 'written' but unfortunately we do not live in a entirely written world.

This is a robustness parameter and Q2 says;
different columns (different lots and/or suppliers)

To my opinion 3 lots is more than enough (not bad but not necessary)..2 different lots and/or vendors will be enough

[Mattias]

Agree, I use different batches of columns since it is mentioned in the ICH guideline. Two batches is probably suffcient (ICH is not very detailed)

We must not forget that the validation is not only something that we do for the authorities. If there is large batch-to-batch variation of the columns and/or you have a tight separation, it is good to know if the method will work after the validation...