Catalytic Fluorophotometric Determination of Molybdenum(Ⅵ) Based on Fluorescence Quenching Effect

Based on the catalytic action of Mo(Ⅵ) on the oxidation of KI by H2O2 in dilute H3PO4 medium to give free iodine (in form of I-3) which in turn reacted with acridine orange leading to quenching of fluorescence of acridine orange,a fluorophotometric method for determination of Mo(Ⅵ) was proposed.Linear relationship was found between values of ΔF(F0-F) determined at wavelengths of 446 nm (λex) and 505 nm (λem) and concentration of Mo(Ⅵ) in the range of 0.16-2.4 μg·L-1.Limit of detection (3s/k) of the method found was 0.10 μg·L-1.The proposed method was used in the determination of Mo(Ⅵ) in samples of green bean,tea and mineral water,giving values of recovery ranged from 93%-99%,and of RSD′s (n=5) less than 5%.