Monitoring of Ortho-Phosphates in Wastewaters Based on the Oxidizing Effect of Molybdenum on Diphenylamine in A Formic Acid Solution Environment
A new approach towards the spectrophotometric determination of ortho-phosphates is described. The method is based on the reaction of phosphate with the by-products of the oxidation reaction between diphenylamine and molybdenum (VI) in a formic acid solution environment. The final product absorbs at 340 nm allowing for the determination of ortho-phosphates at concentrations as low as 0.44 mg L−1 by using a very small sample volume. The calibration curve is linear in the range of 0.5-3 mg L−1 yielding recoveries higher than 96% in various sample matrices. Under the optimum experimental conditions side reactions with other ions that usually have high affinity for molybdenum ions are absent or minimum allowing for the interference free determination of . The only interference rises from the partial decomposition of organic or acid-hydrolysable phosphorus, which is codetermined with ortho-phosphates as a result of the extreme acidic conditions. However, their effects are minor compared to the interferences usually observed with the traditional methods.
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Document Type: Research Article
Affiliations: Department of Chemistry, University of Ioannina, 45110, Ioannina, Greece
Publication date: February 1, 2003