Dear fellow subscribers to Isogeochem,
Regarding the H/D ring test, I had a number of inquiries from collegues new to
Isogeochem, what this test is all about.
I therefore attach two messages that I sent out last year. These should explain
some of the background. For further information, please load down the
correspondence in Isogeochem that was started by a communication from Max
Coleman on Sept. 22nd, 1995.

Please note that the information in those messages is not up to date any more.
Regards		Willi


---------- Forwarded Messages ----------

From:	Willi Brand, 100563,2352
TO:	(unknown), INTERNET:[log in to unmask]
DATE:	10/16/95 1:07 PM

RE:	Copy of: Hydrogen Gas Tests

Dear everyone,
I refer to my proposal to initiate a test for measuring hydrogen isotopes from
different gases in order to establish the performance of the mass spectrometry
hardware and separate it from the water-hydrogen conversion.

I had a number of positive responses which encouraged me to pursue this matter
further. 

I have contacted the german gas manufacturer Messer Griesheim in Duisburg. They
recently established a facility to generate gases with certified isotopic
compositions. They are willing to provide hydrogen gas (equilibrated) with dD
values around +200, -100 and -400. I told them not to meet these values exactly
because I want gases with unknown compositions in that range. They are willing
to prepare 2 batches per composition so that we can have 40 participants,
dividing into two groups corresponding to the batches (each batch gives 20
bottles of identical isotopic composition at atmospheric pressure)).
Messer Griesheim will also handle the sending of the bottles. 
The preparation of the flasks and the manufacturing of the appropriate valves
(these are not their standard valves!) will take some time. It is expected that
the test can start in January or February '96.

If you want to participate please send me an e-mail with your full shipping
address. I will forward your address to Messer Griesheim and you will receive
three flasks and three valves. By signing up you assume the obligation to
provide results within a period of 4 weeks upon receipt of the flasks. You also
must send the three valves back to Messer Griesheim (you may keep the flasks)
within a period of 2 months. If you don't return the valves you will receive an
invoice from the company. In case you want to keep the valves you just pay the
required amount (list price).
In case more than 40 labs sign up, we will have to line up or ask MG to make
another batch. I will decide on the best way to handle this when I see that the
number of labs easily exceeds 40. I might even have to limit the number of
participants.

I urge every participating lab to -please- not contact other labs for
comparison. The danger of having results polished even unwillingly is just too
high. The test is meant to be a blind test in order to get the best conclusion
we can get.
The results should be communicated directly to my e-mail address. I will compile
the results in an appropriate statistical manner and communicate this back into
ISOGEOCHEM.

Regards			Willi Brand

Dear all,
in order to avoid too much writing I am communicating through ISOGEOCHEM who has
signed up to now for the test. You may  miss certain names on the list, so you
might want to take this as an opportunity to inform other colleagues about this
test. As of Thursday, Oct.19, the following labs/people have expressed their
interest to participate:

T. Vennemann	D. Mattey		R. Kalin		J. Dighton
D. Zhang
C. Kendall	B Spiro		B. Vaughn	T. Heaton		L.
Wassenaar
C. France-Lanord	Z. Sharp		T. Brenna	M. Emmons
K. Simon
J. O'Neill		B. Meyer		K. Muehlenbachs	J. Valley
M. Coleman
R. Drimmie	P. Dennis	I. Begley		J. Morrison	M.
Jaklitsch
T. Coplen		R. Michener

These are 27 labs up to now with an estimated number of 35 mass spectrometers.
This is a good number already, but I would like to have more than 50 mass specs
involved.
With respect to the protocol I'm open to suggestions. What I have in mind is to
NOT standardize to SMOW or VSMOW but to have a gas A set to zero permil and have
the other two gases B and C measured against it. This avoids any lab offset. It
also allows each lab to allocate stretching factors to their mass specs
independent of a scaling that might become necessary for the sample preparation
procedure
I intend to have a form sent to every participant together with the gases. There
should be one form filled out per instrument. The form should be faxed to me
without further comments.
The information on the form should be the type of mass spec, the experimental
conditions (H3 factor, pressure in the inlet and signal intensity for both ion
currents) and the actual measurements. Here I propose to have 3 independent
measurements per gas, i.e. 3 separate inlet procedures. This will give us a
total of 6 numbers for the comparison from each instrument.
To ISOGEOCHEM I will report a summary of the results including the individual
numbers and mass spec type without reference to the individual lab.
Please feel free to make other suggestions.
Regards		Willi

End of forwarded messages............................................