Dear Florian,
Indeed, not much is said about the origin of the SRM915a (and former SRM915)
in literature - many studies use the material as standard, but they just
mention the material and not its origin (except the distributor, of course).
Best description is given in the certificate at the NIST web-site,
reporting:
This Syandard Reference Material (SRM) is certified as a chemical of known
purity. etc
Further on page 3:
Source of material: The calcium carbonate used for this SRM was obtained
from the J.T. Baker Chemical Co, Philipsburg, N.J.
This unfortunately is not completely informative, unless this chemical
company can tell what they used for producing this pure material, if they do
know after such a time period (and if they still exist?). Looks very much a
dead-ended street to me.
Not much but still something...
Best wishes,
Pier.
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> Dear List Members,
>
> Reading the interesting infos about NBS-19 and other calcites I wonder if
> anybody can give me information on the source of NIST SRM915a. This is the
> official standard for calcium isotopes. Details on the chemical composition
> are available from NIST, but there is no information what material it is
> made from (limestone, marble, etc.). It has a very low 44Ca/40Ca
> composition for a limestone.
>
> Florian Boehm
>
>
>
> ***************************************************
> Florian Boehm
> Leibniz-Institut f. Meereswissenschaften, IfM-GEOMAR
> FB 2, Marine Biogeochemie/Ostufer
> Wischhofstr. 1-3, D-24148 Kiel
> Germany
> email: [log in to unmask]
> http://www.geomar.de/~fboehm/
> Tel.: (49)431-600-2104
> ***************************************************
>
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