Hi Steve--

Sticking three to five pure Cu wires down an alumina tube works 
well--there have been some comments earlier on isogeochem about building 
your own reactor tubes, but I can't find them right now.  The alumina 
tubing runs ~ $30 US (even from Thermo), you can get away with the 0.05" 
OD, 0.02"ID ones for this purpose (though they don't do so well for HD 
runs as graphite reduction tubes).  We passivate them by running at 700 
(max temp setting on GCC) and pushing through short pulses of oxygen  
(for our set up, system is in backflush mode with O2 on and we quickly 
shut off O2 and put it back in normal mode).  That's to burn off any 
organic contaminants--unfortunately it does shorten the lifetime a bit. 

When we take the old reduction tube out, we'll notice the copper oxide 
is a layer along the bottom, so it may not be as effective after 
rejuvenation.  I haven't tried cranking the temp on the GCC above the 
max, so I can't say if it gets too hot inside the box for the circuits 
if you did raise it to 850.

take care--

gerry

p.s.  It may take a couple of attempts to make your own reduction tube.  
For me, it's not cost effective to make an oxidation tube--I waste too 
much Pt.  Also, you can use a piece of glass capillary tubing to push 
the Cu wires into the alumina tube so they are centered.

Stephen Taylor wrote:

> Hi all,
>
> Quick question for GCC III users:
>
> Is it possible to passively rejuvenate the reduction reactor of a GCC 
> III system?
>
> I heard mention that heating it to 850 oC for short periods of time 
> will do the trick. Anyone have any comments/experience/maintenance 
> recipes?
>
> Thanks,
> Steve
>
> Stephen Taylor
> Lab Manager, Isotope Science Lab,
> University of Calgary, Physics & Astronomy,
> 2500 University Dr. N.W.
> Calgary, Alberta,
> Canada, T2N 1N4
> (p) 403 220 8268
> (f) 403 220 7773
> [log in to unmask]
> www.phas.ucalgary.ca/isl