Spectrophotometric Determination of Molybdenum(Ⅵ) with 5′-Nitro-Salicylfluorone and Its Application

5′-Nitrosalicylfluorone (5′-NSF) was used as chromogenic reagent in the spectrophotometric determination of molybdenum(Ⅵ).In a dil.H3PO4 medium and in the presence of non-ionic surfactant OP,a stable and orangered colored complex was formed between Mo(Ⅵ) and 5′-NSF,with absorption maxima at the wavelength of 528 nm,and molar absorptivity (ε528) of 1.22×105L·mol-1·cm-1.Beer′s law was kept with concentration of Mo(Ⅵ) within 0.30 mg·L-1.The proposed method has been used in the determination of microamounts of molybdenum in carbon steel and low alloy steel containing no or small amounts of tungsten and titanium giving results in consistency with the standard values.