Dear Eric and others interested in the H/Device technique,
during development of the H/Device at Finnigan in Bremen it became
obvious that the grain size and hence surface area of the chromium was
an important parameter. Reducing the chromium will certainly alter this
property and hence affect the results. Not recommended.
We tried to get the used chromium out of the reactor. We used
concentratred HCL, HNO3 and a combination of both with no success at
all. The chromium oxide is extremely stable. Reducing with hydrogen
obviously is not an option. Thus we were forced to use the reactor only
once. Matthias Gehre in Leipzig to my knowledge mixes the chromium with
quartz chips in order to recycle the reactor tube? This will reduce the
number of samples and possibly reduce precision, too, but it may be an
On the other hand, we measure 180 aliquots with one reactor. This
amounts to about 1US$ per reaction which does not seem too much for me.
Another solution would be to find a local supplier. But: the quartz
needs to be of rather high quality, completely free of gas inclusions.
Regards from Jena Willi
Willi A. Brand, Stable Isotope Laboratory [log in to unmask]
Max-Planck-Institute for Biogeochemistry
Carl-Zeiss-Promenade 10, 07745 Jena, Germany Tel +49-3641-643718
P.O.Box 100164, 07701 Jena, Germany Fax: +49-3641-643710