Abstract
Colorimetric determination of inorganic phosphate in micro amounts of human urine by molybdenum blue method was studied.
Ammonium molybdate solution was mixed with Bi(NO3)3 nitric acid solution and as reducing reagent, 1-amino-2-naphthol-4-sulfonic acid, Na2SO3 and Na2S2O5 were dissolved together. Those reagents remained effective for more than several months. The molybdenum blue developed was very stable and the intensity did not change at least for 2 hours.
The recommended analytical procedure was as follows: 0.0025ml of urine adjusted to pH5.4 was taken by the use of a micro pipette. One ml of distilled water and 2ml of ammonium molybdate solution were added and shaken vigorously. Being stood for about 5 minutes, 10ml of distilled water and 0.5ml of the reducing reagent were added and absorbance was measured after 5 minutes at 730mμ by a 10mm cell. The most suitable reaction temperature was 2035°C.
