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H2SO3 dissolves Ag and Sn capsules. Al capsules work ok. They can be
made by hand relatively easily!
good luck,
Carrie
On Dec 22, 2005, at 12:50 PM, Cristina Castanha wrote:
> I am trying to decide on the lesser of evils regarding elimination of
> inorganic C before 13C determination on solid samples by mass
> spectrometer.
>
> Our samples are Oklahoma soils. They don't fizz when acid is dropped
> and
> they all have less than 0.2% gravimetric CaCO3 equivalent. But because
> this
> level of inorganic C could still raise the 13C content by 4 per mil I
> would
> like to compare the 13C content of treated vs untreated soils.
>
> Browsing the archives I find that HCl or H2SO3 treatments are
> preferable to
> H3PO4 or the HF treatments. The Harris et al (2001) HCl fumigation is,
> however, purported to consume some organic C and thereby alter the 13C
> content of the remaining organic matter, whereas the Verardo
> et al (1990) H2SO3 method is purported to damage the analyzing
> equipment.
>
> Is it clear that the Verardo et al method -- in which 0.4 ml of 8%
> sulfurous
> acid is added to each capsule -- is more aggressive on the mass
> spectrometer
> than the HCl fumigation with 12M HCl?
>
> Can someone please outline the appropriate adjustments to the Verardo
> et al
> method (e.g. using use Ag, not Al, capsules?). And, is there any
> reason why
> one can't fumigate with H2SO3 instead of dropping it in each capsule
> several
> times? If fumigation is plausible, what strength is recommended?
>
> Thanks very much
> -Cristina
>
>
Dr. Carrie Masiello
Assistant Professor
Department of Earth Science MS 126
Rice University
6100 Main St.
Houston, TX 77005
phone: 713-348-5234
fax: 713-348-5214
http://www.ruf.rice.edu/~masiello
lab page: http://terra.rice.edu/department/faculty/masiello/RIGG/
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