Surfactant-Sensitized Catalytic Spectrophotometric Determination of Trace Amount of Manganese

In the presence of surfactant polyethylene glycol-400 (PEG-400), the color-fading of the dyestuff “sunset yellow” by oxidation with sodium persulfate was catalyzed by manganese(Ⅱ), and the stability and speed of the color-fading reaction were obviously enhanced. Based on these facts, a surfactant-sensitized catalytic spectrophotometric method for determination of trace amount of manganese(Ⅱ) was proposed. Linear relationship between the magnitude of decrease in absorbance ΔA and mass concentration of manganese(Ⅱ) was obtained in the range of 0.05-4.0 mg·L-1. Detection limit (3S/N) found was 20 μg·L-1. In the determination of trace of manganese(Ⅱ) in water samples by the proposed method, values of recovery found by standard addition method were in the range from 98.6% to 101.8%, with values of RSD′s (n=5) less than 1.5%.