Sodium sample in which nitrogen exists in form of sodium nitride, lithium nitride and calcium nitrideis solved by distilled water and produce ammonia. Ammonia is relieved when solution is heated, then it isabsorbed by hydrochloric acid to produce ammnium chloride. In alkaline solution, ammonium chlorideconverts into ammonia. Ammonia reacts with hypochlorite and phenol that produces a blue indophenol.Nitrogen is determined by 751G type spectrophotometry at the absorption wavelength of 635 nm. The work condition of 751G type spectroscopy, colorimetric condition, smicture of the apparatus Sodium sample in which nitrogen exists in form of sodium nitride, lithium nitride and calcium nitride solved by distilled water and produce ammonia. Ammonia is relieved when solution is heated, then it isabsorbed by hydrochloric acid to produce ammnium chloride. In alkaline solution, ammonium chlorideconverts into ammonia. Ammonia reacts with hypochlorite and phenol that produces a blue indophenol. Nitrogen is determined by 751G type spectrophotometry at the absorption wavelength of 635 nm. The work condition of 751G type spectroscopy, colorimetric condition, smicture of the apparatus