Concentration and analysis of numerous nitrogenous organic substances in natural waters

Abstract Nitrogenous substances take a great part of organic matter found in natural waters, used for drinking water production. Their global evaluation requires a special method the amount of organic nitrogen is obtained as the difference between total nitrogen (oxidation by persulfate in alcaline solution) and the sum of all mineral forms. Organic nitrogen is generally constituted of: humic substances (fulvic acids), chlorophylls, amino acids, peptides and proteins, herbicides and other nitrogenous organic micropollutants. Macromolecular compounds are separated by filtration or ultrafiltration (humic substances, chlorophylls) or their concentration is evaluated by colorimetric methods (humic substances), or after acid hydrolysis (proteins which give simple amino acids). The small (soluble) molecules must be first concentrated; either on an ion-exchange resin (amino acids) or by extraction with an organic solvent (micropollutants and herbicides). Amino acids are analyzed by liquid chromatography and dete...