Determination of trace manganese in municipal sludge by catalytic spectrophotometry

In a weak acid medium(HAc-NaAc buffer solution),trace manganese catalyzes fading reaction of light green SF oxidized by potassium periodate in the presence of nitrilotriacetic acid,and its fading extent is linear with the concentration of Mn?.Based on this,a new catalytic spectrophotometric method for determining trace Mn? is developed.The results show that the maximum absorption wavelength of the complex is at 650 nm and the detection limit of the method is 0.060 μg/L for Mn?.Beer's law is obeyed for Mn? in the range of 0～0.006 mg/L.The method has been applied to the determination of trace manganese in municipal sludge with satisfactory results.