Changing carrier gas in USP methods

[Mo]

Hi to all,
We have been using Nitrogen as a carrier gas instead of Helium as defined in the USP for OVI method IV.
Now QA wants to know whether this is allowed, without being seen as a devaition from the USP that would require a revalidation.
I dont think it is a major deviation since:
The selectivity should not differ from one gas to the other,
and the resultant chromatographic results meet the specified system suitability requirements.

Any thoughts on whether the change of carrier gas is a major deviation from the method that would require re-validation?
Thank You

[chromatographer1]

Call or email the USP and ask them.

best wishes,

Rod

[mcmelof38]

Be careful with this approach with QA / USP. The USP more than likely does not have a straight answer. Any guidance they give you will be viewed legally as the opinion of their staff member not USP policy. The only official USP policy comes from their written updates (PF, etc.)