Most likely you have a reasonable pressure differential in some spot -
somewhere in the system air bubbles get compressed (and dissolved) under
high pressure, then the pressure drops as you reach the column, and the
bubbles re-form. This may not happen with water due to lower viscosity or
perhaps less initial bubbles. Moving the flow restrictor (backpressure
generator) may have something to do with this.
Solutions - try adjusting the backpressure valve to a considerably lower
value and move it back where it belongs. Check your system for kinks in the
tubing, clogged tubes, or user-installed thin tubes where the system design
calls for thicker ones.
Artem
-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Ailong
Ke
Sent: Thursday, July 03, 2008 5:13 PM
To: [log in to unmask]
Subject: [ccp4bb] air bubbles in the Bio-Rad Duoflow system
Hello All,
I own a Bio-Rad Duoflow system for almost a year. The machine lived
up to some of the recommendations I saw on this board. However, there
is this annoying problem with air bubbles entering columns and I
cannot figure out the source. The system would be free of any air
bubbles in the beginning, and performs fine when water is loaded
using needle/syringe into the 5ml superloop and then injected into
the column. When protein samples are injected the same way, a lot of
air bubbles would appear and get trapped inside the ion exchange
column, leaving yellowish marks on the Uno columns and eventually
reducing their performance. I've been a FLC/AKTA user for about ten
years and have never seen such problems. I doubt it is due to a
faulty injection valve because we recently had it replaced for other
reasons. We did move a backpressure generator (a little black piece)
from post-column position to before-column, otherwise we cannot run
sizing columns in a reasonable flow rate.
I'd like to hear if you have similar experiences and how you fixed
the problem. Thanks a lot!
Ailong
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