Organic nitrogen is defined functionally as organically bound nitrogen in the tri negative oxidation state .It does not include all organic nitrogen compound . Analytically, organic nitrogen and ammonia can be determined together and have been referred to as "Kjeldahl nitrogen, " a term that reflects the technique used in their determination. Organic nitrogen included such natural materials as proteins and peptides, nucleic acids and ures, and numerous synthetic organic materials.Typical organic nitrogen concentrations vary form a few hundred micrograms per liter in some lakes to more than 20 mg/L in raw sewage.