head space vial deviation??

[pat_val]

Hi!,

How much head space vial deviation allowed when following USP method? Instead of 20 mL , if we use 10 mL ....is it allowed? Please let me know reference if litrarue avilable about deviation for GC from USp method...

[krickos]

Hi

In this thread you have a updated link in the last post to a FDA Q&As:
viewtopic.php?t=9538

I would not recommend changing vial size without any validation work attached to it as you change the equlibrum between gas an liquid phase, but frankly USP do not state the vial size "Transfer 5.0 mL of Test Stock Solution to an appropriate headspace vial, add 1.0 mL of the Standard Solution, apply the stopper, cap, and mix. "

However 20ml vial would be appropiate as one tries to avoid fillling the vial more than to half the volume. Not 100% but on agilent headspace samplers I think the headspace needle actually can end up touching the liquid if 6ml is put into a 10ml vial. Though I must say that I have not verfied it my self just been told to not to.