Hi Paul:

Many years ago I had a chance to spend a week working with scientists at the
IAEA lab in Seiberdorf, Austria (just outside of Vienna).  At that time they
had an ANA-Sira connected to a Carlo Erba EA (I believe an NA1500) with a
splitter valve.  They were measuring m/e 30 to monitor it's increase to
indicate when the copper was no longer converting all of the N2 compounds to
N2 gas.  At a certain level they would remove the reduction tube (while it
was still hot) and then they would connect it to a H2 gas cylinder.  They
would regenerate the reduced copper for several hours and then re-introduce
the reduction tube back into the EA.  This generation EA had the tapered
combustion/reduction tube.  My understanding was that this regeneration was
not as effective as replacing the copper with fresh reduced copper and I
have not come across anyone else that has tried to regenerate their own
copper.  Although the method of manufacturing reduced copper would be
similar ie. a batch of copper is heated as H2 gas is flushed over the
copper.  Is suspect that overnight regeneration would be more beneficial.  I
don't remember the H2 being used was anything than pure H2 and of course
there was the danger of explosion.

I think for the price of reduced copper, it may not be worth while for
everyone to set up a system of regenerating their copper.  Trying to do this
with the reduction tube in place would add additional hazards especially if
the reduction tube cracked during the process.

Regards
Nik 

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Paul Brooks
Sent: January 18, 2006 4:39 PM
To: [log in to unmask]
Subject: Re: copper regeneration

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.