胭脂红催化光度法测定痕量钴

Catalytic spectrophotometric method for determination of trace cobalt(Ⅱ) with carmine

在1.0×10-2mol/L NaOH溶液介质中,痕量Co对过氧化氢氧化胭脂红的褪色反应有强烈地催化作用,使得体系在506 nm处的吸光度明显降低,从而建立了催化光度法测定痕量Co的方法。在最佳实验条件下,在7.43×10-3～0.198μg/mL质量浓度范围内,体系吸光度变化值ΔA与Co2+浓度之间基本符合比尔定律,其表观摩尔吸光系数ε为1.94×105L.mol-1.cm-1,检出限为6.23 ng/mL。该方法可直接用于维生素B12中痕量Co的测定。

A new catalytic kinetic spectrophotometric method for the determination of trace cobalt was studied. The method was based on the catalytic effect of Co（ Ⅱ ） on the oxidational discoloration of carmine with hydrogen peroxide in the medium of 1.0 × 10-2mol/L NaOH. Under the optimum experimental conditions, The Beer＇ s law was obeyed in the range of 7.43 × 10 -3 - 0. 198 txg/mL for cobalt concentration, the apparent molar absorptivity and the detection limit were 1.94 × 105 L · mol^-1 · cm^-1 and 6.23 ng/mL, respectively. This method has been used to determine trace cobalt in Vitamin B12 with satisfactory results.