Dear Listmembers,

I need some help on the following:

We extracted soils with K2SO4 (0,125M, 50mL), and then freeze dried those
samples in tin cups. It was the first time we used this technique and didn't
realise the danger.

Apparantly the very high sulfur-content in the cups causes serious
contamination of the GC (we use Anca-SL), when measuring the samples for
13C.

Are there any of you that have experienced the same problem? Is there a way
to modify the equipment (to scrub out the sulfur), or is there another way
to get rid of the sulfur?

Thanks a lot in advance!

Best regards,

Peter

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Peter Vervloedt
Laboratory Of Applied Physical Chemistry
Ghent University
Coupure 653
9000 Gent

tel.: +32 9 264 6000
       +32 9 264 6048
fax.: +32 9 264 6230
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-----Oorspronkelijk bericht-----
Van: Stable Isotope Geochemistry <[log in to unmask]>
Aan: [log in to unmask] <[log in to unmask]>
Datum: vrijdag 20 oktober 2000 9:06
Onderwerp: Re: [ISOGEOCHEM] Isotopic
carbonatealterationduetothermaltreatment?


Micha,

depending on the water content and the presence of metastable carbonate
phases in the core there may be transformation of the carbonate fraction
into
more stable phases. Depending on a number of boundary conditions O isotope
exchange may occur. This will probably be not a serious problem for C
isotopes. During roasting some OM will decompose and create CO2.

Regards, Michael

Micha Horacek wrote:

> Dear isogeochemists,
>
> I think I have to formulate my request more precisely:
>
> The palmag cores are demagnetised by heating to temperatures above 350° C
> for at least two hours (but I do not think much longer) and "roasted" at
> maximum temperature of 500° for twenty minutes.
> The cores consist of massive rock, not powder. The cores are from impure
> carbonate rocks with low organic contents.
> Can the demagnetisation process possibly change the isotope ratios, for
> example if the carbonate content of the sample is rather small?
>
> Cheers,
> Micha