We run single foram samples, normally 10-30 ug, on the Kiel IV + Thermo
Delta V plus, with same size NBS19. Our long term precision is 0.05 for
d13C and 0.10 for d18O, for small samples (size 10-30 ug). Even though I
require sample size must be >10 ug to give reasonable delta values, sample
size down to 8 ug also can yield enough gas for a reasonable analysis.


Wei Huang, Ph.D.



Stable Isotope Lab Manager


New Core Lab Rm#212

Lamont-Doherty Earth Observatory of Columbia University

61 Route 9W
Palisades, NY 10964
Lab: 845-365-8143 <845-365-8306>
[log in to unmask]


On Wed, Oct 25, 2017 at 12:24 PM, Alan Mix CEOAS <[log in to unmask]>
wrote:

> MAT252, Kiel-III, capillaries balanced at low voltage, cleanliness is next
> to godliness, no slope corrections, “normal” glass reaction vials.
>
> Results to 10 micrograms on calcite standards — see graphic below (in the
> 10-21 microgram range, d13C external precision of 0.03 to 0.04, d18O
> external precision of 0.03 to 0.06 --two different numbers because two
> different standards, offset between standards maintained at about 5.5
> permil for d18O, 1.2 permil for d13C, so no problem with gas mixing or
> memory).  Results on real biological samples will be less precise because
> of, well, biology.
>
> I’m not particularly fond of approaches that that do slope corrections as
> a function of mV as they can make standards look OK but you never really
> know they are right. Not religious about this, but very cautious. Can’t
> fight physics  — if the capillaries jump flow regime at low pressures,
> that’s the limit and the two sides don’t necessarily do it at exactly the
> same point.  On our current system, the practical limit appears to be about
> 10 micrograms.
>
> Alan.
>
>
>
> —————
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> —————
> Alan C. Mix, PhD
> Distinguished Professor of Earth, Ocean, & Atmospheric Sciences
> President of The Oceanography Society (www.tos.org)
> Fellow of the American Association for the Advancement of Science
> Fellow of the American Geophysical Union
>
> Oregon State University
> CEOAS Administration Building 104
> Oregon State University
> Corvallis, OR 97331-5503 USA
>
> email: [log in to unmask] <[log in to unmask]>
> www: http://ceoas.oregonstate.edu/profile/mix/
>
>
>
> On Oct 25, 2017, at 7:30 AM, Christopher Maupin <[log in to unmask]>
> wrote:
>
> Dear Isogeofolks, a broad, community query here:
>
> I’m curious what your successes and/or failures running extremely small
> carbonate samples have been like. Seeing the uptick in individual foram
> papers in recent years as piqued my curiosity to reach out to the broader
> iso-sphere.
>
> What instrument/peripherals have you tried/are you using?
> What are the smallest masses of CaCO3 you are able to successfully measure?
> What precision are you routinely achieving on these successful
> measurements?
> What is your “recipe” for success?
>
> Many thanks!
> ________________________________________________
> Chris Maupin, Ph.D.
> http://christophermaupin.strikingly.com
> Research Associate and Facilities Manager
> Stable Isotope Geosciences Facility (SIGF)
> Geography Department
> Texas A&M University
> 405 Eller O&M Building 3147 TAMU
> College Station, TX 77843 USA
> Email: [log in to unmask], [log in to unmask]
> Mobile: (512) 810-8437
>
>
>
>
>
>
>