Dear listmembers,

I would like some comment on the following:

During our 13C in soil analyses we have noticed that the standard deviations
of some samples were better than others. In the beginning I thought this was
probably caused by contamination during weighing, so we analysed them again.
And again the same samples had a better standard deviation than others. All
samples have +/- the same carbon-content and were measured in the same
batch.

Of course I know that there is such a thing as a matrix-effect, but can it
really influence the results that much, even if the weighed amount and the
'type' is the same (type = all soils, just different fractions and different
locations)? I am talking about variations in standard deviation (n=3) of
about 0.1 (sdevs around 0.15 permil for 'worst' samples and about 0.05
permil for 'best' samples).

Thank you very much!

Cheers,

Peter


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Peter Vervloedt
Laboratory of Applied Physical Chemistry
Faculty of Agricultural and Applied Biological sciences
Ghent University
Coupure, 653
9000 Gent
Belgium

tel.: +32 (0)9 264 6048
fax.: +32 (0)9 264 6230
http://fltbwww.rug.ac.be/isofys

"I have not failed. I've just found 10000 ways that won't work"
- Thomas Alva Edison (1847-1931)
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