基于0. 02mol/LHCl介质中,痕量钴(Ⅱ)对重铬酸钾氧化偶氮胂Ⅲ褪色反应的催化作用,建立了测定痕量钴(Ⅱ)的动力学光度法。钴(Ⅱ)质量在0 ~4. 0μg/L范围内服从比尔定律,方法检出限为0. 076μg/L,在25mL溶液中,测定0 1μg钴(Ⅱ)的相对标准偏差为3. 8% (n=11)。讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响。研究了反应的最佳条件,并测定了一些动力学参数。催化反应的表观活化能为40. 73kJ/mol。此法可用于井水、蜂蜜和维生素B12中钴(Ⅱ)的测定,相对标准偏差为1. 8% ~5. 7%,标准加入回收率为99. 6% ~104. 2%。 Based on the catalytic effect of trace cobalt (Ⅱ) on the fading reaction of arsenazo Ⅲ by potassium dichromate in 0.02 mol / L HCl medium, a kinetic spectrophotometric method for the determination of trace cobalt (Ⅱ) was established. Beer’s law was obeyed for the mass of cobalt (Ⅱ) in the range of 0-4.0 μg / L, and the detection limit of the method was 0. 076 μg / L. The relative standard deviation of 0 1 μg cobalt (Ⅱ) in the 25 mL solution was 3.8 % (n = 11). The effects of acidity, reactant concentration, temperature, reaction time, interfering ions and other factors were discussed. The optimum reaction conditions were studied and some kinetic parameters were determined. 73kJ / mol. The apparent activation energy of the catalytic reaction was 40. 73kJ / mol. This method can be used for the determination of cobalt (II) in well water, honey and vitamin B12 with a relative standard deviation of 1.8% -5.7% and a standard recovery of 99.6% -104.2%.