FI-Catalytic Photometric Determination of Molybdenum in an Unstable Reaction System

In an acetic acid medium of pH 2.9,and in the presence of KI and o-phenanthroline,the redox reaction between H2O2 and 4,4′-tetramethyldiaminodiphenylmethane was significantly catalyzed by Mo(Ⅵ),and an unstable blue product was formed having its absorption maximum at the wavelength of 603 nm. By applying flow-injection technique,absorbance of the unstable blue product was taken down at definite time intervals. Linear relationship between values of absorbance and concentration of Mo(Ⅵ) was kept in the range within 0.5 mg·L-1. Detection limit (3k/s) found for the method was 9.6×10-6g·L-1. The proposed method was applied to the determination of Mo(Ⅵ) in waste water,and results of recovery tested by standard addition method were in the range of 95.6%-103.2%.