Analysis of Carbonate δ13C δ18O

 

Summary

We use a Kiel III Carbonate Device coupled to a Finnigan Delta Plus for a dual-inlet based δ13C and δ18O measurement of small carbonate samples.

Reference Materials

We employ carbonate international reference materials NBS19 and L-SVEC to put our δ13C and NBS19 and NBS18 to put our δ18O carbonate samples on the VPDB scale. We have a suite of internal reference materials that span the same range of NBS19, L-SVEC, and NBS18 for day to day analysis.

Sample submission

If you would like to submit carbonate samples for δ13C and δ18O analysis, please have your samples ground to a fine powder and in a uniquely and simply labeled container. We require 20 to 120 µg of carbonate for a single analysis. Please send enough sample material so as to provide ~200 µg of carbonate. See the table below for sample analysis pricing.

Exhaustive description of analysis

The Kiel III carbonate device is an automated system for the digestion of carbonate with 100% phosphoric acid (specific gravity 1.90 - 1.92) and purification of the carbon dioxide (CO2) product. For traditional pure-carbonate samples, five drops of phosphoric acid are dropped onto 20-120 µg of carbonate in an evacuated, leak tested, pyrex reaction vessel and allowed to react for ten minutes at 70 °C. Both CO2 and H2O are trapped in a small volume cold finger held at -196 °C with liquid nitrogen. When the reaction is complete, the trap is warmed to -110 °C to keep H2O but allow CO2 to expand for gas volume measurement. The CO2 is then frozen into a second small volume cold finger trap held at -196 °C with liquid nitrogen. Once complete, the trap is warmed to 26 °C allowing the CO2 to pass into a Finnigan Delta Plus isotope ratio mass spectrometer (IRMS) via a dedicated capillary for mass / charge 44, 45, 46 measurement alternately with that of a reference CO2 gas roughly calibrated to the VPDB scale held in a variable volume bellow. Eight comparisons of sample / reference are made to yield initial raw δ13C and δ18O values.

Calculations

Please see the Correcting Carbonate Data from Kiel method.

Suggested reading

  • McCrea JM. On the isotopic chemistry of carbonates and a paleotemperature scale. Journal of Chemical Physics, 18, 849-857. (1950).
  • Coplen TB, Kendall C, Hopple J. Comparison of stable isotope reference samples. Nature, 302, 236-238. (1983).
  • Tobin TS, Schauer AJ, Lewarch E. Alteration of micromilled carbonate δ18O during Kiel Device analysis. Rapid Commun. Mass Spectrom., 25, 2149-2152. (2011).
  • Santrock J, Studley SA, Hayes JM. Isotopic analyses based on the mass spectra of carbon dioxide. Analytical chemistry, 57, 1444–1448. (1985).

Carbonate δ13C δ18O Analysis Pricing

All analysis prices are per sample.

  • UW Budget Number,
    User Provided Labor
  • $9
  • To be eligible for this rate, you must provide a UW budget number for billing as well as have the ability and availability to run the sample analysis yourself from start to finish.
  • Method: Phosphoric acid digestion
  • Rates double for the analysis of sample sets containing less than 10 samples.
  • Request analysis

    Or I have a user account and I want to check in my samples.
  • Off Campus Funding, User Provided Labor
  • $10
  • To be eligible for this rate, you must have the ability and availability to run the sample analysis yourself from start to finish. Analysis will be paid for through an off-campus address.
  • Method: Phosphoric acid digestion
  • Rates double for the analysis of sample sets containing less than 10 samples.
  • Request analysis

    OR I have a user account and I want to check in my samples.
  • UW Budget Number, Lab Provided Labor
  • $12
  • To be eligible for this rate, you must provide the lab with a UW budget number for billing. An IsoLab lab technician will perform the sample analysis for your sample set.
  • Method: Phosphoric acid digestion
  • Rates double for the analysis of sample sets containing less than 10 samples.
  • Request analysis

    OR I have a user account and I want to check in my samples.
  • Off Campus Funding, Lab Provided Labor
  • $14
  • This is the lab's default billing rate. We will apply this rate when no UW budget number is provided and your sample analysis was performed by an IsoLab lab technician.
  • Method: Phosphoric acid digestion
  • Rates double for the analysis of sample sets containing less than 10 samples.
  • Request analysis

    OR I have a user account and I want to check in my samples.

We welcome individuals from all departments and from on or off the University of Washington campus to visit our facility, and to take advantage of our expertise. Please contact us for more information.

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