Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Original Papers
Spectrophotometric Determination of Phosphate Anion Based on the Formation of Molybdophosphate in Ethylene Glycol–Water Mixed Solution
Hajime KATANOTadaharu UEDA
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2011 Volume 27 Issue 10 Pages 1043

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Abstract

New appropriate reaction system was found for spectrophotometric determination of phosphate anion. This spectrophotometric method is based on the color development due to the formation of yellow molybdophosphate anion in acidic ethylene glycol–water (EG-W) mixed solution containing Mo(VI) species. The solution containing e.g. 20 mM Na2MoO4, 0.1 M HCl, and 40% (v/v) EG is colorless, and becomes immediately yellow by addition of phosphate anion. Thus the method is simple, rapid, and easy to carry out. Although Si(IV) species is well known to interfere with the determination of phosphate anion in many cases, the EG-W Mo(VI) solution remains colorless after addition of silicate anion at 1 mM level, indicating that no yellow molybdosilicate anion was formed in the EG-W solution. Under an optimized condition, the absorbance at e.g. 400 nm of the EG-W P(V)-Mo(VI) solution was proportional to the concentration of phosphate anion with good reproducibility, and the detection limit was 1 μM. Also the present method is less interfered by high concentrations of potassium and ammonium cations and oxidative nitrite anion as well as silicate anion.

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© 2011 by The Japan Society for Analytical Chemistry
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