Ammonia Assay Kits

Ammonia is primarily produced in the liver, kidneys, and intestines, with much of it resulting from the breakdown of amino acids. Since ammonia is a substance harmful to the body, it must be detoxified rapidly. While much of the generated ammonia is recycled, a portion of it is converted into urea and excreted in the urine via the kidneys.

In mammals, ammonia is converted into urea by the ornithine cycle (urea cycle) in the liver (Figure 1). By measuring the ammonia in the blood, liver function can be assessed. In particular, blood ammonia levels tend to be high in cases of severe liver disease.

Fujifilm Wako’s Lab Assay™ Ammonia is based on the modified Fujii-Okuda method¹⁾. This method utilizes the Berthelot reaction that produces indophenol²⁾. With this kit, ammonia can be conveniently measured using a microplate.

Principle of the Ammonia assay using modified Fujii-Okuda methods

By adding a protein remover solution to the sample, interfering substances for the color reaction are removed, and various enzymes in the sample are inactivated at the same time. Phenol and the reaction catalyst, sodium pentacyanonitrosylferrate(III) (sodium nitroprusside), are added to the supernatant. After making the solution alkaline, oxidation with sodium hypochlorite produces indophenol, which exhibits a blue color. The concentration of ammonia nitrogen in the sample can be determined by measuring the absorbance of the blue color (Figure 2).

1. Okuda, H. and Fujii, S.: The Medical Frontline, 21, 622(1966). (Japanese)
2. Nambara, T.: Bunseki Kagaku, 16(1), 86(1967).
   臨床化学分析に用いる呈色反応の機構 (Japanese)