DEVELOPMENT OF A METHOD FOR DISSOLVED ORG ANIC NITROGEN DETERMINATION

We used a photo-chemical reactor (500W mercury lamp) to oxydise organi c nitrogen compounds into inorganic species measurable by ion chromato graphy (nitrate; nitrite, ammonium). The organic nitrogen concentratio n is determined by measuring the increase of the inorganic nitrogen sp ecies concentrations after irradiation. We tested two oxydizing reagen ts: hydrogen peroxide (widely cited in the literature) and potassium p ersulfate in acidic conditions. We showed that hydrogen peroxyde does not allow a total recovery of the inorganic forms of nitrogen. Consequ ently, we choose to use potassium persulfate in acidic conditions. We successfully applied the procedure to determine dissolved organic nitr ogen in natural water. A mechanism describing how the molecular compos ition of the organic nitrogen compounds influences the nature and comp osition of the oxidation products is briefly presented.