Catalytic spectrophotometric determination of manganese(II) with arsenazo I and potassium periodate

A new kinetic spectrophotometric method for the determination of trace amounts of Mn(Ⅱ) was studied. It was based on the catalytic effect of Mn(Ⅱ) on the discolouring oxidation of ArsenazoⅠ by potassium periodate. The influential factors of reaction and the optimum conditions were investigated in detail. The linear calibration curve from 0 to 80 μg/L of Mn(Ⅱ) and the detection limit of 6.3×10-9 g/mL was reported. The relative standard deviation for 60 μg/L of Mn(Ⅱ) was 2.6%(n=11). A kinetic equation was derived and the apparent activation energy of catalytic reaction was found to be 130.4 kJ/mol. The method was used to determine Mn(Ⅱ) in edible wild herbs and fruit with satisfactory results.