Hi Robert

we several times tried to reanimate Cr reactors of the H/Device which still had large amounts of "fresh" chromium. It never gave  the desired reproducibility and the values were always severely shifted. My working model was that the heating up under vacuum somehow alters the chromium ("activated surface"?) and after exposure to air this surface is severely damaged. But maybe this depends on the mesh size and filling of the chromium charge in use.

hope this helps

Axel

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Axel Suckow
Isotope Hydrology Laboratory
International Atomic Energy Agency
Wagramer Strasse 5
A-1400 Vienna
Austria
Phone: 0043 1 2600 21767 or 26762
email: [log in to unmask] <mailto:[log in to unmask]>
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''


> -----Original Message-----
> From: Stable Isotope Geochemistry [mailto:[log in to unmask]]On
> Behalf Of Geldern, Robert
> Sent: Freitag, 3. September 2004 11:41
> To: [log in to unmask]
> Subject: Re-heating of Cr Reactors (H/Device)
>
>
> Hallo,
> due to some technical problems here we have a number of Cr filled
> reactors where the Chromium is not entirely used. We had to switch of
> the H/Device after e.g. 100 samples and cool it down.
> Has anybody experience with re-heating these reactors in the
> H/Device to use the rest of Chromium? I do not expect any problems
> but I have not tried it yet.
>
> greetings,
> Robert
>
> --
> Dr. Robert van Geldern
> Leibniz Institute for Applied Geosciences (GGA)
> S3: Geochronology and Isotopehydrology
> Stilleweg 2, 30655 Hannover, Germany
> phone: +49-(0)511-643-2313 (office), -2539 (lab)
> fax: +49-(0)511-643-3665
> mailto:[log in to unmask]
>

This email message is intended only for the use of the named recipient.
Information contained in this email message and its attachments may be
privileged, confidential and protected from disclosure. If you are not the
intended recipient, please do not read, copy, use or disclose this
communication to others. Also please notify the sender by replying to this
message and then delete it from your system.