Dear Anthony,

Thanks for the suggestion. 
We already use a CO cylinder; we calibrate the gas against IAEA references
(waters or benzoic acid) or against sugars from a ring test. But, when you
have long batches of ethanol samples to measure, you cannot change
configuration (liquid to solid) and use such products.

The idea is to have a well known (calibrated) gas, to correct daily or
weekly the big tank of CO and its inevitable drifts and variations (due to
the temperature, to the pressure, to the lunar phases or whatever). With a
small bottle, by comparison via dual inlet, it should be much simpler than
weight dozen of standards.

A presto,
Giovanni

----------------------------------
Giovanni Calderone, PhD
EC-Joint Research Centre
Institute for Health & Consumer Protection Physical and Chemical Exposure
Unit - BEVABS
TP740 via Fermi, 2 21020 ISPRA Italy
Tel. Off.: +(39) 0332 78 5668
Tel. Lab.: +(39) 0332 78 5258
Fax: +(39) 0332 78 9303
http://ihcp.jrc.it/
http://hosting.jrc.cec.eu.int/pce/
e-mail: [log in to unmask]


-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Anthony M. Faiia
Sent: martedì 22 novembre 2005 20:06
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Isotopically known CO: suppliers

Why don't you buy some high grade CO without a known isotopic composition
and then calibrate it against known standards such as carbonate? For our
measurements, we run two different isotopic standards with each batch of
samples and don't bother to calibrate the reference gas. 

Anthony

--- You wrote:
Dear all,

I'm having very big problems in finding suppliers of CO with d18O and d13C
determined, in small cylinders (1L) to use in dual inlet systems.
Some of the suppliers cannot send over-ocean (OzTech in USA nor from
Mexico). Others apparently don't have the gas anymore in catalogue (Messer
Grisheim, in Italy at least: Messer Germany did not yet reply me).

So: anyone could help me?

Thank you!!

----------------------------------
Giovanni Calderone, PhD
EC-Joint Research Centre
Institute for Health & Consumer Protection Physical and Chemical Exposure
Unit - BEVABS
TP740 via Fermi, 2 21020 ISPRA Italy
Tel. Off.: +(39) 0332 78 5668
Tel. Lab.: +(39) 0332 78 5258
Fax: +(39) 0332 78 9303
http://ihcp.jrc.it/
http://hosting.jrc.cec.eu.int/pce/
e-mail: [log in to unmask]
--- end of quote ---