Influence of ultrasonic waves on phosphate determination by the molybdenum blue method

Abstract

Polymeric bonds between molybdate monomeric ions in acidic medium were broken by 40 kHz ultrasonic wave irradiation, improving the reaction kinetics with o-phosphate in the presence of ascorbic acid. It could be assumed that the ultrasonic wave irradiation of molybdate solution in acidic medium during 1.0 min was sufficient to increase the rate of the molybdenum blue formation. The approach was applied to the o-phosphate determination in natural waters. Precise results were obtained in the range from 0.05 to 0.50 μg ml−1 (r=0.9994; N=6), and the detection limit was estimated as 0.027 μg ml−1 PPO4. Advantages over the classical analogous procedure are emphasised.