Thanks everyone for the TOC standard pointers! This will get me going!

Anthony


------------------------------------------------------
Anthony L. Michaud
Physical Sciences F-686
Arizona State University
Tempe, AZ 85287-1404

Tel: 480-727-8033
Fax: 480-965-8102

http://geopig.asu.edu/keck/index.html

***Windsurf Everywhere***
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-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Gilles St-Jean
Sent: Wednesday, May 11, 2005 6:44 AM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] TOC high standard?

Hi Anthony
We have prepared a heavier standard by mixing an enriched (99 at% for both
13C and 15N, and a separate 99% 13C Glycine ) with a natural abundance
Glycine.  We have targeted +25 and are just now making a +8 permil standard.
Both sets are used for EA and DOC for daily normalisations and yes they are
homogeneous after recristalisation.  The solution is dried at 50oC and we
wind up with about 15g of the stuff in the end. Enough to last about 10 to
15 thousand analysis.  The problem with using DIC is it's very short shelf
life and shifting values, as Daniel mentionned, with carbonates.  We do not
use DIC as standards anymore.  Since the reaction for DIC and DOC is pretty
much 100% in the TOC Analyser, then a DOC standard works for both quite
well.

The mixing calculations can be done by mass balance or dilution (M1V1 + M2V2
= M3V3 where M is in permil).  I did a similar prep 15 years ago making a 4L
heavy HD water standard from an enriched water.  Using the dilution equation
I targeted +15 and got +15.6.

The Glycine was purchased through Isotec which is a Sigma Aldrich company.
I think you can now find the enriched products in the Sigma catalogue.

If you need more info, contact Paul Middlestead at
[log in to unmask] or call him at xt 6839 (main number below).

Gilles



Gilles St-Jean
Chercheur / Research Scientist
Université d'Ottawa / University of Ottawa
Sciences de la Terre / Earth Sciences
140 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
Tel: 1-613-562-5800 xt 6830 (Bureau / Office)
                    xt 6839 (Bureau / Office Lab)
                    xt 6836 (IRMS lab)
Téléc. / Fax: 1-613-562-5192
Courriel / E-mail: [log in to unmask]
Toile / Web: www.isotopes.science.uottawa.ca






  _____

        De : Stable Isotope Geochemistry [mailto:[log in to unmask]] De
la part de Anthony L. Michaud
        Envoyé : 10 mai 2005 12:21
        À : [log in to unmask]
        Objet : [ISOGEOCHEM] TOC high standard?



        We are getting our working standards together for DIC/DOC using an
OI Analytical TOC analyzer coupled to a Delta Plus Advanatage. We’d like to
have a working standard that is somewhere around -5 to +5 permil vs PDB so
that it is close to our TIC values. Do any of the TOC-IRMS users out there
have suggestions on where I might find an ok standard that is so enriched?
Not much info in the archives concerning TOC standards…



        Thanks for any help!



        Anthony







        ------------------------------------------------------

        Anthony L. Michaud

        Physical Sciences F-686

        Arizona State University

        Tempe, AZ 85287-1404



        Tel: 480-727-8033

        Fax: 480-965-8102



        http://geopig.asu.edu/keck/index.html



        ***Windsurf Everywhere***

        ------------------------------------------------------