溴甲酚绿-高碘酸钾催化光度法测定痕量Mn(Ⅱ)

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

研究了在pH 4.1HAc—NaAc介质中,以氨三乙酸为活化剂,Mn(Ⅱ)催化高碘酸钾氧化溴甲酚绿褪色反应的条件及影响因素,建立了动力学光度法测定痕量Mn(Ⅱ)的新方法。方法的线性范围为0.4～12μg/L;检出限为0.12μg/L,对8μg/L Mn(Ⅱ)平行测定11次的相对标准偏差为0.09%。该催化反应的表观活化能为42.24kJ/mol,反应的表观速率常数为3.5×10-4 s-1。该方法具有较高的灵敏度和选择性,用于井水、自来水样品中锰含量的测定,结果令人满意。

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.