Analysis of Dissolved Organic Carbon (DOC) in Water by TOC-IRMS
The SIF provides 13C isotope analysis of dissolved organic carbon using a TOC analyzer interfaced to an IRMS.
Dissolved inorganic carbon (DIC) is no longer analyzed using this system; please refer to DIC in Water.
Analysis
DOC is analyzed for 13C using an O.I. Analytical Model 1030 TOC Analyzer (OI Analytical, College Station, TX) interfaced to a PDZ Europa 20-20 isotope ratio mass spectrometer (Sercon Ltd., Cheshire, UK) utilizing a GD-100 Gas Trap Interface (Graden Instruments). Samples are acidified and purged with helium off-line to remove all dissolved inorganic carbon (DIC). Depending on sample concentration, a 1- to 4-mL aliquot of sample is transferred into a heated digestion vessel and reacted with sodium persulfate to convert DOC into a pulse of CO2. The CO2 is carried in a helium flow to the isotope ratio mass spectrometer where the 13C/12C ratios are measured. Samples are corrected based on included laboratory standards calibrated against NIST Standard Reference Materials.
Analytical Precision
0.6 for 13C of DOC
e-mail: sif@ucdavis.edu | phone: 530-752-8100 | fax: 530-752-4361 UC Davis Stable Isotope Facility | Department of Plant Sciences One Shields Avenue, Mail Stop #1 | Davis, California, 95616 | USA |