This presentation reviews the performance and limitations of a wet chemical oxidation carbon analyzer interfaced with a cavity ring-down spectrometer (WCO-CRDS) for measuring carbon concentration and isotopic composition in natural water samples. Difficulty in accurate assessment of carbon species using total organic carbon analyzers, including chloride interference in analyzing DOC has been described by Aiken and others. One of the key remaining factors limiting analysis of isotopic composition of dissolved organic carbon in natural waters is an observed chloride interference of wet chemical oxidation techniques in which the chemical oxidant, often persulfate, reacts with abundant chloride ion to generate chloride radicals in competition with the preferred product, CO<sub>2</sub>. Some efforts to mitigate this problem include optimizing the oxidant to chloride ratio, removal of chloride by complexation, and increasing reaction times. Further work remains to be done on the problems associated with oxidation inefficiency of highly refractory compounds and the attendant isotopic effects during reaction. The WCO-CRDS approach requires more total carbon than continuous flow isotope ratio mass spectrometry, nevertheless WCO-CRDS can be applicable to a wide range of DOC concentration and water types.

Carbon tracing: Environmental applications of wet oxidation total organic carbon cavity ring-down spectroscopy

253rd National Meeting (2017)

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