Catalytic Spectrophotometric Determination of Manganese (II) with Bromocresol Green and Potassium Periodate

A new catalytic spectrophotometric method for the determination of trace amount of Mn(II)has been developed.It was based on the catalytic effect of Mn(II)on the discolouring oxidation of bromocresol green by potassium periodate in the presence of an accate buffer of pH 4.1 and nitrilotriacetic acid(NTA)as an activator.At the optimum experimental conditions,the linear range was 0.4～12μg/mL,the detection limit was 0.12μ8g/L,and the relative standard deviation was 0.09% obtained from 11 standard solution each containing 8μg/mL of manganese.The apparent activation energy of catalytic reaction is 42.24KJ/mol,the apparent rate constant of catalytic reaction is 3.5×10-4 s-1.The results showed that the method has high sensitity and selectivity.This method was used to the determination for Mn(Ⅱ) in water samples with satisfactory results.