Hi Sarah,

I’d advise against this. We’ve analyzed a lot of rocks that are much less than 0.1% C—with considerably less material. I suggest measuring the C isotopes first on a much smaller sample. Start with 20 mg and run with zero dilution.

Typically, we would like to have 10 micrograms of N, but we’ve found 5 microgram of N gives good reproducible results. I would suggest, after measuring C on a much smaller amount, analyze 25 then 50 mg samples first. Calculate how much you’ll need for 5 or 10 micrograms. We’ve analyzed 100 mg samples with a blank in between. Use a fresh insert. You might be able to run 10 or so at this level.

Run blanks of your tin boats, of course.

Marilyn Fogel

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Dr. Marilyn L. Fogel, 
Distinguished Professor and Wilbur W. Mayhew Professor of Geo-Ecology
Director of the Environmental Dynamics and Geo-Ecology Institute (
Dept. of Earth and Planetary Sciences
University of California Riverside
900 University Ave.
Riverside, CA 92521
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From: Stable Isotope Geochemistry <[log in to unmask]> on behalf of Sarah Grosshuesch <[log in to unmask]>
Reply-To: Stable Isotope Geochemistry <[log in to unmask]>
Date: Monday, September 9, 2019 at 11:28 AM
To: <[log in to unmask]>
Subject: [ISOGEOCHEM] 300mg sediment EA-IRMS

Anybody ever run a 300mg sed sample w/ very low (<0.5%) carbon and nitrogen by EA-IRMS ?
I am wondering if a Costech 4010 ECS semi-micro loop for oxygen will be adequate for 

Thanks -  Sarah
Sarah Grosshuesch
Researcher | Large Lakes Observatory | [log in to unmask]

2205 E. 5th St., Duluth, MN 55812
University of Minnesota Duluth
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