Moritz and Eddy,

The value I actually gave was the value as given in one of my book chapters
on standards by Manfred Groening, referring to the Boehlke et al. (2003)
paper. I looked again in the Boehkle et al (2003) paper, and indeed, a
number of values is given.
I am not certain why Manfred selected this particular value (can you react
yourself on this, Manfred?), but I guess since Boehlke and coworkers took
into consideration the 'capital delta'17O signature (quoted is the work by
Greg Michailski and coworkers: Michailski et al. (2002) Anal. Chem., 74:
4989-4993) of IAEA-NO-3 (= IAEA-N3) in their determination of the d18O
value, it was considered the most reliable determination of the d18O for
that reason!
It also must be notified that there is a clear difference between 'off-line'
(CO2, O2) and 'on-line' (CO) methods of roughly 2 - 3 per mil., whatever the
reason. Worrying enough....

In any case, we really need to have consensus about the values of standards
and reference materials. Having a list of values for the same standard or
reference material is not serving anybody.
If the given d18O value is the best one (I followed Manfred Groening in
this) might raise dispute by some. But we have to decide which value we do
accept! We need to have an isotopic value solidly calibrated and traceable
to the N-isotope scale - that should be the choice. Otherwise we cannot
compare with each other and may bias our interpretations.

Pier.


> Eddy,
>
> The Boehlke paper is indeed the latest report on d18O of IAEA-N3. But be
> aware that there are quite a number of other (lower) values reported (in
> parts compiled in the Boehlke paper).
>
> Moritz
>
>
> On Tuesday, December 9, 2003, at 05:16  AM, eminet wrote:
>
>> Dear list members,
>> Has anyone of you a d18O value for the reference IAEA-NO-3 (for which
>> d15N=4.7)?
>> Thanks,
>> Eddy
>>
>> Eddy Minet
>> Centre for the Environment
>> Trinity College Dublin
>> Dublin 2 (Ireland)
>> e-mail: [log in to unmask]
>> tel: +353(0)1 608 2403
>> mobile: +353(0)86 827 4921
>>
>>
> Moritz F. Lehmann
> Department of Geosciences
> Princeton University
> Guyot Hall
> Princeton, NJ 08544
> phone: (609) 258-7544
> fax: (609) 258-0796         e-mail: [log in to unmask]
>
>