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Hiroto,

As you probably know, you can regenerate the CuO by adding O2 to the He stream.  The full instructions should be in the manual.  It has been our experience that each regeneration will last for a shorter time than the previous regeneration until it is no longer worth trying to regenerate the CuO.  The problem appears to be a build up of what we assume is SiO2 (or something similar) formed from the siloxane groups that bleed off the column.  Whatever the deposit is, it is plain to see under a low-power microscope.

You can reuse the tubes by dissolving out the used CuO with acid.  I use aqua regia because I had some left over but concentrated nitric acid might also work.  I hold the tube vertically in a retort stand with the bottom in a beaker of acid.  On the top I place a pipette bulb and use that to draw the acid up the tube.  The reaction is quite slow and it will take most of a day to dissolve the CuO.  Every hour or so you should let the acid drain back into the beaker and then draw up a fresh lot.  After that I wash thoroughly with clean water and oven dry.

Repacking is quite easy but fiddly - so I get the relevant PhD student to do it :-)

Cheers,
David Wheeler

Professional Officer
Geochemistry Laboratory					
School of Earth and Environmental Sciences        			
University of Wollongong,               
Wollongong, 2522, NSW          		
Australia

'These days, if a scientist can't get
 an answer by isotope analysis, he ain't hep'

                       - Isaac Asimov, 1959





-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Hiroto Kawashima
Sent: Wednesday, 14 July 2010 5:23 PM
To: [log in to unmask]
Subject: [ISOGEOCHEM] oxidation furnaces

Dear Dr. Nick Collins

I'm Hiroto Kawashima of assistant professor from Akita prefectural university of
Japan. Now, I try to research source apportionment of suspended particle matter
(PM2.5 , PM10 etc.) and VOCs in air and pesticide in soil using carbon and nitrogen
and hydrogen isotope. I have a question. Could you tell me.

I have a GC/C/IRMS(Isoprime). But the oxidation furnaces(quartz tube, 600mm * 6mm OD
* 0.65mm ID with CuO) can't be used after approximately 200 samples(especially
pesticide). The quartz tube is too expensive. I want to purchase quartz tube (ceramic
tube?), CuO each and hand-made packing.

You use to pack your combustion tube? After how many samples do you analyze, you
exchange the tube? Please tell me information of the oxidation furnaces of Isoprime
GC/C/IRMS.

Best wishes

Hiroto Kawashima

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Hiroto Kawashima
Department of Management Science and Engineering,
Faculty of Systems Science & Technology, Akita Prefectural University
84-4 Ebinokuchi Tsuchiya, Yurihonjo City, Akita Prefecture, Japan
[log in to unmask]

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