Sorry to bring up an old subject, but I was out of town and could not join
into the original discussions.  We might be able to help some of you with
your needs for a methane standard.  We have both off-line and on-line
systems for doing C and H isotopes on C1 through C5 hydrocarbons. We
specialize in these analyses.  If you have a methane that you want to use as
a working standard, we could do a high precision analysis for you with our
off-line systems.  We also have the IAEA NGS standards that Mike Verkouteren
wrote about and we could run your gas along with splits of these samples.
That way when the NGS gases are finally calibrated, you will have a good
calibration of you working standard.  In the mean time, since the NGS
standards are pretty well known, you would have a value that is probably
accurate to within the abilities of online systems.

My suggestion would be to buy a cylinder of high purity methane.  We could
provide small gas cylinders in which a split could be taken and submitted
for analysis.  You can check our web site at www.isotechlabs.com for
information on prices and turnaround times.

Dennis

Dennis D. Coleman
Isotech Laboratories, Inc.
1308 Parkland Court
Champaign, IL 61821
phone (217) 398-3490
fax (217) 398-3493
web page: www.isotechlabs.com
email: [log in to unmask]



-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]]On
Behalf Of Peter Vervloedt
Sent: Tuesday, November 14, 2000 4:31 AM
To: [log in to unmask]
Subject: CH4 reference material - injection of CH4 on solid/liquid
module


Dear Listmembers,

Our problem with the 13C in CH4 measurements is to find the right reference
gas. I would greatly appreciate any tips on otbaining CH4 reference material
with known 13C-content. The gas should contain no other hydrocarbons and
should have a low CO2-content too. Thanks.

In the mean time, i'm experimenting with a self-placed septum purge injector
on our Anca-SL module (for solids and liquids). With this adjustment I'm
hoping to be able to measure 99.995 pure CH4 versus a solid or liquid
13C-reference by oxidizing it to CO2. I have managed to obtain good
peakshapes (similar to normal solid or liquid samples) but the recovery is
quite low (70-80% approx.). Any tips on that would be very welcome - see
famous quote at the bottom of this email :-).

Thanks in advance, and keep up the good work!

Peter.

---
Peter Vervloedt
Laboratory of Applied Physical Chemistry
Ghent University
Coupure, 653
9000 Gent
Belgium

tel.: +32 (0)9 264 6048
fax.: +32 (0)9 264 6230
http://ftlbwww.rug.ac.be/isofys

"I have not failed. I've just found 10000 ways that won't work"
- Thomas Alva Edison (1847-1931)
---