Dear Bruno and others,
All samples are grinded very well (using a planetary ball mill), and there
is no visual difference between the samples. It is true, however, that the
texture of the samples is different (clay-like vs sandy). But in both cases
the homogenity is as good as it can get (according to the price of our ball
mill it should be, at least ;-)
The sample weight used is about 10 mg, so this should be enough to give a
homogenic sample. (also, as mentioned, the carbon-content is +/- the same).
Do not get me wrong, we are satisfied with the results we obtain from the so
called 'worst' samples (SD ~ 0.15 permill). It is just that the difference
is quite noticable and does make me curious.
Laboratory of Applied Physical Chemistry
Faculty of Agricultural and Applied Biological sciences
tel.: +32 (0)9 264 6048
fax.: +32 (0)9 264 6230
"I have not failed. I've just found 10000 ways that won't work"
- Thomas Alva Edison (1847-1931)
From: Stable Isotope Geochemistry [mailto:[log in to unmask]]On
Behalf Of Bruno Glaser
Sent: Friday, January 19, 2001 1:46 PM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] sample matrix importance
do you have thought about homogeneity of your samples??? Especially soil
have to be ground very thoroughly, depending the weight you are using. Is it
true that the samples more reproduable, i.e. the samples having smaller
deviation are those ground finer than the other ones???
Dr. Bruno Glaser
Institute of Soil Science and Soil Geography
University of Bayreuth