An automated method for the determination of dissolved organic carbon in seawater using continuous thin-film UV oxidation

• Published in: Marine chemistry 1983-01, Vol.12 (1), p.59-68
• Main Authors: Mueller, Hansrudolf, Bandaranayake, Wickramasinghe M
• Format: Article
• Language: English
• Subjects: Marine; oceanography
• ISSN: 0304-4203; 1872-7581
• DOI: 10.1016/0304-4203(83)90028-2

An automated method for the determination of dissolved organic carbon in seawater using a Graentzel DOC analyser is described. A thin film of sample is rapidly and continuously oxidised in a spinning quartz reactor by UV irradiation, emitted by a ‘low pressure’ mercury lamp. The concentration of carbon dioxide is measured by an infra-red gas analyser. The conditions of photo-oxidation have been examined and optimum conditions for maximum performance are described. The determination limit of the procedure is 0.05 mg Cl −1; the 95% confidence limits are ±0.02 mg Cl −1 using a working range from 0.2–2 mgCl −1. The reaction time is 1–3 minutes, the residence time of the sample in the reactor is about 5–10 minutes and the sampling frequency is a maximum of 6 samples per hour. The method proved to be reliable both in the laboratory and aboard a research vessel. Preliminary investigations indicate that the instrument can be adapted for the determination of dissolved organic carbon and phosphorus simultaneously.