Catalytic Spectrophotometric Determination of Trace Cobalt(II) Based on Oxidation of Phenosafranine by Potassium Periodate

A new catalytic spectrophotometric method for the determination of trace cobalt(Ⅱ) based on the oxidetion reaction between potassium periodata and phenosafranine in the presence of nitrilotriacetic acid as an activator in HAc-NaAc buffer solution(pH=4.0) has been developed.The optimum conditions have been studied.The apparent activation energy of catalytic reaction is 65.23 kJ·mol-1.The detection limit of this method is 8.84×10-10g·mL-1 for cobalt(Ⅱ) and linear relationship is in the concentration range of 0.010～1.20 μg/25mL for cobalt(Ⅱ).The recovery is in the range of 94%～103% and RSD is 3.6%～5.1%.The method was applied to the determination of trace cobalt in grain samples with satisfactory results.