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Determination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710

April 1, 2012

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1710 is to present a method to determine the δ13C of dissolved inorganic carbon (DIC) of water. The DIC of water is precipitated using ammoniacal strontium chloride (SrCl2) solution to form strontium carbonate (SrCO3). The δ13C is analyzed by reacting SrCO3 with 100-percent phosphoric acid (H3PO4) to liberate carbon quantitatively as carbon dioxide (CO2), which is collected, purified by vacuum sublimation, and analyzed by dual inlet isotope-ratio mass spectrometry (DI-IRMS). The DI-IRMS is a DuPont double-focusing mass spectrometer. One ion beam passes through a slit in a forward collector and is collected in the rear collector. The other measurable ion beams are collected in the front collector. By changing the ion-accelerating voltage under computer control, the instrument is capable of measuring mass/charge (m/z) 45 or 46 in the rear collector and m/z 44 and 46 or 44 and 45, respectively, in the front collector. The ion beams from these m/z values are as follows: m/z 44 = CO2 = 12C16O16O, m/z 45 = CO2 = 13C16O16O primarily, and m/z 46 = CO2 = 12C16O18O primarily. The data acquisition and control software calculates δ13C values.

Publication Year 2012
Title Determination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710
DOI 10.3133/tm10C18
Authors Glenda L. Singleton, Kinga Revesz, Tyler B. Coplen
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Techniques and Methods
Series Number 10-c18
Index ID tm10C18
Record Source USGS Publications Warehouse
USGS Organization Reston Stable Isotope Laboratory