Analysis of total dissolved nitrogen in natural waters by on-line photooxidation and flow injection

✍ Scribed by I.D. McKelvie; M. Mitri; B.T. Hart; I.C. Hamilton; A.D. Stuart

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 609 KB
• Volume: 293
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(94)00101-4

✦ Synopsis

A sensitive automated method for the determination of total dissolved nitrogen (TDN) is described . This method is based on the complete conversion of inorganic and organic nitrogen species to nitrate by photooxidation in an alkaline peroxodisulphate medium . Following on-line photooxidation, sodium metabisulphite is added to reduce excess peroxodisulphate reagent, and a portion of the resultant solution is injected into a flow-injection manifold for the measurement of nitrate by cadmium reduction to nitrite, diazotization, coupling and detection at 540 mn . The method is comparatively fast (ca . 25 determinations ht), has a detection limit of 0 .03 mg 1t N, and is linear up to 3 mg 1t N. The PTFE tubing photoreactor is simple to construct, and because detection is by visible spectrophotometry, the method could be readily employed using either commercial or low-cost laboratory-built flow-injection analysis systems .