Hi Bill,
Those kind of nitrate standards would be more precious than gold.  We
were looking for wild range of O-18 nitrate, when we developed our
method (Revesz and others Anal.Chem. 1997, v.69, #21) but did not find
any.  All the chemicals had O-18 values close to O-18 value of air O2,
22 - 24 per mill.  Finally, we used natural samples to test our method,
and their range was  +4 - +50 per mill.
Kinga


Bill Showers wrote:
>
> Isotope Geochemists,
>
> We are looking for nitrate standards that have a range of N-15 and O-18.
> The reagent grade nitrate that we have purchased from different vendors all
> seem to have about the same isotopic composition.  Has anyone been able to
> find nitrate of differing isotopic composition, what is really needed for
> pollution studies is nitrate that has positive N-15 and negative O-18?
>
> Bill Showers
> ----------------------------------------------------------
> William J. Showers
> Dept. of Marine, Earth, & Atm Sciences
> North Carolina State University
>
> (919) 515-7143 - voice
> (919) 515-7802 - fax
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