Determination of serum-phosphate without deproteinization by ultraviolet spectrophotometry of the phosphomolybdic acid complex

Abstract

Phosphate may be determined in serum without deproteinization as the phosphomolybdic acid complex by UV-spectrophotometry. The rate of complex formation is dependent on the acidity and the concentration of molybdate. The photometric measurements should be performed at a longer wavelength than the maximum absorptivity of the phosphomolybdic acid complex to permit practical high concentrations of molybdate in the reagents. Citric acid will hinder the complex formation, but will not interfere with the stability of the phosphomolybdic acid. The phosphomolybdic acid complex is determined by adding citric acid to the sample before (blank) and after (test) the molybdate. The analytical procedure has been automated on a Greiner GSA II, Greiner Electronics, Switzerland.

Key Words:

• phosphate analysis
• phosphomolybdic acid complex
• serum
• human