Dear Simon,

Poor combustion problems are common for the first 10-20(?) BaSO4 samples
by EA. The samples may not be in the "combustion zone" until enough ash
is present. You can improve reproducibility in combustion by adding 0.2
to 0.5 mg of V2O5.

Ann-Lise Norman
=====================================
Atmospheric Division
Isotope Sciences Laboratory
Department of Physics and Astronomy
The University of Calgary
Alberta, Canada
=====================================

Simon Poulson wrote:
>
> Hello everyone,
>
> As there's a small S conversation going on, I thought I'd ask if anyone
> might have any suggestions as to how to analyse d34S of BaSO4 by elemental
> analysis?  I find that I often get very variable yields of SO2, which I
> think is due to inconsistent heating of BaSO4 during Sn combustion, and
> hence incomplete decomposition of BaSO4.  I've tried a couple of things to
> try and increase the temperature/duration of the Sn combustion (e.g. using
> a larger Sn cup, using two Sn cups, adding PbO or sucrose, etc.), and this
> helps, but doesn't completely solve the problem.  I'm currently using a
> single quartz tube at 1000 C - has anyone tried using a double tube
> configuration with an alumina tube at higher temperature (1300+ C) for the
> combustion, and then a quartz tube with Cu at 1000 C?  Alternatively, has
> anyone identified an effective additive to promote complete BaSO4
> decomposition?
>
> Thanks in advance for any help or suggestions.
>
> Cheers,
> Simon
>
> *****
> Simon R. Poulson
> Dept. of Geological Sciences, MS-172
> University of Nevada-Reno
> Reno, NV 89557-0138
> USA
> Phone: (775) 784-1104
> Fax: (775) 784-1833
> [log in to unmask]
> *****