Automated quantitative and isotopic ( 13 C) analysis of dissolved inorganic carbon and dissolved organic carbon in continuous‐flow using a total organic carbon analyser

Abstract

A method for the automated 13 C analysis of dissolved inorganic and organic carbon species has been developed to operate on a continuous‐flow isotope ratio mass spectrometer (CF‐IRMS). For natural and anthropogenic carbon species, the 13 C stable isotope has proven to be an excellent environmental tracer. Analytical performance tests were carried out on various organic compounds from easily oxidisable (sugar) to difficult (humic acid). A set of natural samples was also analysed to confirm the flexibility of the system. Analytical precision (2 σ ) is typically <0.20‰ with sample reproducibility from 0.10–0.35‰ depending on reactivity of material. We believe this to be the first successful use of a total organic carbon (TOC) analyser for both dissolved inorganic and, specifically, dissolved organic species for 13 C stable isotope analysis in an automated CF‐IRMS system. Routine analysis is achieved fairly quickly, is relatively simple with little or no sample manipulation, and will allow new and exciting studies for stable isotope research in both natural abundance and organic tracer studies not easily achieved before. Copyright © 2003 John Wiley & Sons, Ltd.