Dear Isogeochemists
I am sorry because I used an attached file. Here is the the text of Boron
intercomparison
Thanks
Sonia



Announcement
BORON ISOTOPE MEASUREMENTS
INTERCOMPARISON EXERCISE

The Istituto di Geocronologia e Geochimica Isotopica (IGGI), Pisa, Italy, on
behalf of, and in collaboration with, the International Atomic Energy Agency
(IAEA), Vienna, Austria, is organizing an intercomparison exercise of boron
isotope measurements. All laboratories and institutes having analytical
capabilities for boron isotopes are invited to take part in the exercise.
The following intercomparison materials, which cover adequately the natural
range of boron isotopic composition, have been prepared for distribution:

B-1 - Mediterranean Sea Water (Ligurian Sea),B content 5 ppm, d11B ” about
+40, amount provoded  50 ml;
B-2 - Groundwater, alluvial aquifer, Cecina R. lower basin (Tuscany),B
content <1ppm, d11B ” between  0 to +10, amount 50 ml;
B-3 - Groundwater, alluvial aquifer, Cecina R. upper basin (Tuscany), B
content <5 ppm,d11B ” between -20 to -30, amount 50 ml;
B-4 - Tourmaline, Elba Island (Tuscan Archipelago), B content 32,500 ppm,
d11B ” between 0 to -10, amount 1 g;
B-5 - Basalt, Etna Volcano (Sicily), eruption July 1998; B content about 10
ppm, d11B ” between 0 to -10, amount provided 30 g;
B-6 - Obsidian, Lipari Island (Eolian Archipelago), B content about 200 ppm,
d11B ” between +5 to -5, amount 30 g;
B-7 - Miocene Marine limestone (Abruzzi), B content <5 ppm,d11B ” between 0
to +10, amount 30 g;
B-8 - Pliocene Clay (Tuscany), B content about 100 ppm,d11B ” between 0 to
-10, amount 30 g.

Rock and mineral samples were ground to fine powder with agate mills. The
powder was mixed mechanically to reach a good degree of homogeneity. This
was indicated by preliminary measurements carried out at the IGGI with
uncertainty of 1 to 3 % for boron concentration measurements (depending on
the rock matrix), and 0.5 ” (2s) for isotope ratio variation determinations.
Those wishing to take part in the intercomparison exercise are kindly
requested to contact Dr. Sonia Tonarini of IGGI (E-mail
[log in to unmask]). The results obtained should be sent to Mr.
Manfred Gröning, International Atomic Energy Agency, Division of Physical
and Chemical Sciences, P.O. Box 100, 1400 Vienna, Austria (E-mail:
[log in to unmask]). IGGI will take part in the exercise under the same
conditions as others.
The laboratories will be requested to report, for each sample and for both
boron concentration and isotope composition, the results of repeated
preparations and measurements with its internal uncertainty, the average
values and the resulting external uncertainty. Information on the method and
the mass spectrometer used for the measurement, as well as any other
information which is considered relevant and useful, will be appreciated.
Forms will be sent together with the intercomparison samples for reporting
the results.
The isotopic results should be expressed in terms of isotopic ratio 11B/10B
and d11B ” vs. the reference material NBS-SRM 951 (boric acid) distributed
by NIST (National Institute for Standards and Technology, US Department of
Commerce, Gaithersburg, Maryland 20899, USA), with 11B/10B = 4.04362 ±
0.00137 (Catanzaro et al., 1970). This reference material is normally
available in all laboratories performing boron isotope measurements.
Together with the intercomparison samples listed above and NBS-SRM 951, some
laboratories may wish to run, as additional control, some of the following
reference materials:
JB-2 (basalt distributed by the Geological Survey of Japan). The boron
concentration of JB-2 is about 30 ppm, the isotope ratio 11B/10B is 4.0725,
and the d11B is +7.1 ”, as derived from the measurements reported so far by
Nakamura et al., 1992, and Tonarini et al., 1997).
IRMM-011, boric acid, with certified 11B/10B = 4.0443 ± 0.0052 (De Bièvre,
1993), or IRMM-611, solution of the same boric acid with certified
concentration and 11B/10B = 4.0444 ± 0.0051 (Lamberty et al., 1992). These
samples are distributed by the IRMM (Institute for Reference Materials and
Measurements, European Union Joint Research Centre, Retiesewg, 2440 Geel,
Belgium).
The results should be submitted within October 2000. Afterwards, a draft
report with the individual data and their statistical elaboration will be
prepared, which will be distributed to the participating laboratories for
comments before preparing the final version. The report and the results will
be further discussed in meetings organized by IAEA at regular intervals on
reference samples and intercalibration of isotopic measurements in
geochemistry and hydrology. The portions of unused samples will become
available at IAEA for future distribution and intercalibration purposes.
Comments and suggestions are most welcome.

Sonia Tonarini
Giorgio Ferrara
Roberto Gonfiantini
Maddalena Pennisi
Istituto di Geocronologia e Geochimica Isotopica del CNR
Area di Ricerca di Pisa ‹ Loc. San Cataldo
I-56010 Ghezzano (Pisa), Italy
Phone +39-050-588276 ‹ Fax +39-050-588360 ‹ E-mail [log in to unmask]


References:



E.J. Catanzaro, C.E. Champion, E.L. Garner, G. Malinenko, K.M. Sappenfield,
K.M. Shields, 1970: Boric acid: isotopic and assay standard reference
materials.. US Nat. Bur. Standards, Spec. Publ. 260-17, 70 pp.
P. De Bièvre, 1993: Certificate Isotopic Reference Materials IRMM-011.
Institute for Refrence Materials and Measurements, EU-Joint Research Centre.
A. Lamberty, A. Verbruggen, V. Holland, W. Lycke, F. Hendrickx, P. De
Bièvre, 1992: A CBNM 11B isotopic reference material. Int. J. Mass Spectr.
Ion Proc., 113, 213-221.
E. Nakamura, T. Ishikawa, J.L. Birck, C. Allègre, 1992: Precise boron
isotopic analysis of natural rock samples using a boron-mannitol complex.
Chem. Geol., 94, 193-204.
S. Tonarini, M. Pennisi, W.P. Leeman, 1997: Precise boron isotopic analysis
of complex silicate (rock) samples using alkali carbonate fusion and
ion-exchange separation. Chem. Geol., 142, 129-137.