Re‐evaluation of high temperature combustion and chemical oxidation measurements of dissolved organic carbon in seawater

Abstract

Various commercial HTC analyzers are now being used in marine laboratories with inconsistent and less than uniform results. A small intercalibration exercise was held in Bermuda to compare results from several commercial HTC analyzers and the traditional wet chemical oxidation method. The exercise utilized a single low carbon water to determine the instrument blank, and a single set of standards was used for all analyses. Five Sargasso Sea water samples from the surface to 4,000 m and a dried extract of dissolved organic matter from a black‐water river were used as the samples for comparison. Analyses by the four methods agreed within 15%, and the seawater values were similar to previously published values. The results demonstrate the importance of careful instrument blank determination and of accurate determination of the CO 2 peak.