By Anonymous on Tuesday, December 7, 1999 - 08:51 pm:
(1)We operate in a GLP/GMP environment. We want to Helium sparge mobile phase as an alternative to the USP method of heating to 45 then filtering. Do we need to execute a protocol to show degassing equivalency? Does anyone have any thoughts/experience?
(2)What are the standard sparging rates and times?
Should these depend on % organic in the mobile phase?
By Anonymous on Wednesday, December 8, 1999 - 12:49 pm:
We are also a GLP/GMP facility. We've never used the USP method you mention. We used to use helium sparging, but in the past few years we've used membrane degassers, available from Hewlett Packard and other suppliers. We have never had any question from the agencies about degassing, as far as I'm aware.
By B.Buglio on Wednesday, December 8, 1999 - 05:57 pm:
A He sparging rate of 30-60ml/min for 20 min works
fine. Equivalent is to draw a vacuum on the mp for
the same length of time. Ive heard concerns voiced
re changing to mp conc w a vaccum however as a
practical matter Ive never experienced a problem.
By Anonymous on Thursday, December 9, 1999 - 11:42 am:
In reference to the response on 12/8/99 at 12:49 pm: On our LCs we have in-line vacuum degassers with PTFE membranes but we still degas our mobile phase before we use it on an LC system. Do you rely solely on the degassing system on the LC to degas your mobile phase?
By juddc on Thursday, December 9, 1999 - 02:38 pm:
When using pre-mixed mobile phases with He sparging, be careful of oversparging the mobile phase as that can lead to irreproducible chromatography. This is due to the differential vapor pressures of the components in the MP. I've found this to be most problematic when using mobile phases with "extreme" (90%)proportions of organic solvent, where small changes in solvent composition have large effects upon selectivity and/or retention.
CJ
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