Abstract:  A new catalytic spectrophotometrin method for the determination of trace amounts of Co(Ⅱ) has been developed. The method is based on the catalytic effect of Cobalt(Ⅱ)on oxidation of acid chrome blue K by potassium periodate with aminoacetic acid as an activator and cationic surfactant of cetyl pyridine bromide(CPB) as a sensitizer. The optimum conditions of reaction and kinetic parameters were assayed. On the optimum experimental conditions, the linear range is 0～100μg/L, and the detection limit is 9.06×10-7 g/L. The sensitivity is increased by 12 times in the absence of the surfactant and activetor. The method can be used for the determination of cobalt(Ⅱ) in tea and Vitamin B12 samples with satisfactory results.

Key words: catalytic spectrophotometry, cobalt, potassium periodate, acid chrome blue K cetyl pyridine bromide (CPB), amino acetic acid(AAA)