continuously stirred mobile phase.

[MestizoJoe]

In the USP monograph for griseofulvin, it calls for the continuous stirring of a mixture of three miscible solvents (thf, acn, and water).

Why would stirring help?

Thanks, I'm just curious.

[Consumer Products Guy]

Does USP stand for Unbelievably Sucky Procedures ?

Unintelligible Standard Practices ?

Unnatural Substandard Protocols ?

Most likely originator of the assay procedure stirred his mobile phase, so it was retained. OK: why? Likely when the monograph was written there was not online ternary or quaternary mixing, so such mobile phases were pre-mixed and pumped from one reservoir. User likely felt that stirring either kept it relatively uniform in regards to preferential evaporation through venting, or used stirring/heat/vacuum to keep the mixture from absorbing gases (before in-line vacuum degassers). Many, many USP procedures are woefully out of date.

[Gerhard Kratz]

I agree with Consumer Products Guy. When I was doing HPLC method development in pharmaceutical industry, 95% off all USP methods did not work. It seams that nowadays it is still the same. Don't worry and just use your online degasser.