Hallo Clemente,
during the Advisory Group Meeting on SI Ref and Intercomp Mat (Vienna, Dec
11-14,1995) they reccommended in group 1 to prepare a depleted BaSO4 RM for
S-34 from IAEA S-3, should be undertaken by Stan Halas and Roy Krouse. The
attempt should be made to realize a significantly O-18 contnet. I do not
know how far the things are done. Please ask Stan Halas in Lublin/Poland.
We have our own lab std BaSO4 of about +13 o/oo (also measured by Stan Halas
and M. Graf/Munich). However, we are still doing some methodical work to get
reliable values.
Nevertheless, we are interested in cooperation on sulphate-O std.

Gerhard
***********************

>
>Like other colleagues that have responded, the only sulphate-O reference
>material I know of is NBS-127.
>
>However, from my point of view, additional reference materials with delta
>18-O different enough from +9.3 permil are badly needed.
>
>Some months ago I asked the group if anybody had an alternative/complement
>to NBS-127, and I am asking the same question again:
>
>Is anybody willing to get involved in the search for other complementary
>materials to be used as reference for sulphate-O? Reagent-grade BaSO4
>should be an easy target, abundant enough and homogeneous enough (at least
>within individual batches) to test.
>
>If anybody is interested or has additional comments, I'm willing to go
>ahead, but I need some other Labs to get results worth trusting.
>
>Cheers,
>
>Clemente
>
>
>-----------------------------------------------
>Dr. Clemente Recio
>Stable Isotope Laboratory
>Fac. de Ciencias
>Univ. de Salamanca
>E 37008 - Salamanca
>      Spain
>
>Phone: (+34) 23 29 44 00 Ext. 1540
>Fax:   (+34) 23 29 45 14
>E-mail: [log in to unmask]
>-----------------------------------------------
>
>
Gerhard Strauch
Centre for Environmental Research Leipzig-Halle Ltd
Department of Hydrogeology
Hallesche Strasse 44
D-06246 Bad Lauchstaedt
Germany
Tel: ++49/34635/73218  Fax: ++49/34635/73287
e-mail: [log in to unmask]