Hi Paul,
I regenerated the oxidized copper some years ago in a quartz tube for
another system (not for the EA). The tube was connected to a rotary vacuum
pump (opposite tube end was plugged) and the oven temperature was 800 C.
It took just couple hours to regenerate copper. In your case, the problem
will be to bring the temperature to 800 C close to the ends (rubber vacuum
hose and rubber plug).
Sergey.

-- 
Sergey OLEYNIK, PhD
Ecology and Evolution
Dept Biological Sciences
University of Illinois, Chicago
845 W. Taylor st.
UIC, 3342 SES
Chicago, IL 60607
Phone: office 312-3550579
lab 312-3550600
Fax: 312-4132435
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On Wed, January 18, 2006 4:38 pm, Paul Brooks said:
> Elemental Analyzer users:
>
> I have just been given a tank of 5% H2 in N2 that in principle should be
> able to regenerate oxidized copper in an elemental analyzer.
>
> I used to do this with pure H2 and a bypass valve system to isolate the H2
> from coming into contact with the air.  Eventually I gave it up as too
> dangerous, and buying finer copper solved the problem.  However, as I
> recall several EA users did this with a 5% H2 in N2 mix as in principle
> this mixture should not be flammable in air.
>
> Does anyone have any words of wisdom on this?  It would seem easy enough
> to
> simply disconnect the top of the copper column and let it vent to
> atmosphere, then connect the 5% H2 mixture to the bottom of the tube.  Any
> idea how long it will take to regenerate?  Also, I recall from previous
> discussions that there might be a problem with N isotope precision
> immediately after regeneration.
>
> Any words of wisdom will be greatly appreciated, including warnings not to
> try it!
>
> Thanks in advance, Paul Brooks.
>