Jean-Pierre,

You are not alone. We have wrestled with this issue a long time. A dD value
of ca. -74 is typical for us on a well-determined, SMOW-SLAP normalized
scale using the uranium reduction technique. Our reproducibilty for other,
in-house hydrous minerals is excellent (often within 1 ?) so that the
question is one of accuracy and not precision. At present we are in the
process of trying to put together another hydrous mineral reference material
for the IAEA. The published dD value for NMS-30 is that to which a number of
labs refer. However, our experience is that we do not obtain the vale of -66
? ourselves.

Bruce



Bruce E. Taylor, Ph.D.
Research Scientist
Geological Survey of Canada
601 Booth Street
Ottawa, Ontario  K1A 0E8
CANADA

PH:  613-995-4673 (office) (temp: 992-7258)
                 992-4046 (lab)
FAX: 613-943-1286
e-mail: [log in to unmask]

Personal URL:
http://www.nrcan.gc.ca/gsc/mrd/bio/taylor_e.html

LSI Lab URL: http://www.nrcan.gc.ca/gsc/mrd/labs/lsilab_e.html

Ottawa Isotope Group: http://www.earthsci.carleton.ca/ottawaisotopegroup/

> ----------
> From:         Girard Jean-Pierre
> Reply To:     Stable Isotope Geochemistry
> Sent:         Friday, September 7, 2001 11:08 AM
> To:   [log in to unmask]
> Subject:      delta D of NBS-30
>
> We recently analyzed NBS-30 biotite for hydrogen isotopes for the first
> time
> (we have mainly used it as an oxygen isotope standard in the past) and
> found
> delta D values much lower than the value of -66 per mil given in the IAEA
> report on reference materials for stable isotopes (1995, IAEA-TECDOC-825).
>
> Does anyone know of any published DeltaD values for NBS-30 other than that
> in the IAEA report ?
>
> Also, if anyone is (has been) using NBS-30 routinely as a standard for H
> isotopes, we would be interested to know what kind of values and
> repeatability you get.
>
>
> Jean-Pierre
>
> ***************************************************************
> Jean-Pierre GIRARD
> BRGM  - ANA/ISO
> 3 avenue Cl. Guillemin, BP 6009
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>