恒电位电解流动注射化学发光分析法测定钢铁中微量钼

建立了钼的恒电位电解流动注射化学发光分析法。在0.02 mol/L的H2C2O4酸度下，使含不具发光活性钼（Ⅵ）的溶液，以1.7 mL/min的流速通过自制的流通式碳电解池时，在-0.60 V(vs∶Ag/AgCl)电位处，钼（Ⅵ）在线还原为钼（Ⅲ），钼（Ⅲ）与鲁米诺在碱性条件下产生化学发光，且发光强度与钼的质量浓度在5.0×10-10～5.0×10-7 g/mL范围内呈线性关系，钼（Ⅵ）检出限为5×10-11 g/mL。大多数常见的阳离子和阴离子对钼的测定没有干扰，Fe3+和Fe2+的允许量较低，但试液通过测定流路中钠型离子交换柱后，Fe3+和Fe2+的允许量提高到1 000倍。方法已用于低合金钢和碳钢标准样品中微量钼的测定，测定值与认定值一致，相对标准偏差在0.68 %~1.3 %之间。

Determination of micro molybdenum in steel by constant potential electrolysis-flow injection chemiluminescence analysis

The determination method of molybdenum by constant potential electrolysis - flow injection chemiluminescence analysis was established. In 0.02 mol/L H2C2O4 solution, the molybdenum（Ⅵ） solution without luminescence activity passed through self-made flow-type carbon electrolysis cell at the rate of 1.7 mL/min. Molybdenum（Ⅵ） was on-line reduced to molybdenum（Ⅲ） at the potential of -0.60 V(vs.Ag/AgCl). Molybdenum（Ⅲ） generated chemiluminescence with luminol under alkaline conditions. The chemiluminescence intensity was linear to mass concentration of molybdenum in the range of 5.0×10-10-5.0×10-7 g/mL. The detection limit of molybdenum（Ⅵ） was 5×10-11 g/mL. Most common positive and negative ions had no interference with the determination of molybdenum. The permissible amount of Fe3+ and Fe2+ was small. However, it could be increased to 1 000 times after the test solution passed through Na-type ion exchange column in the determination flow path. The proposed method was applied to the determination of micro molybdenum in certified reference materials of low alloy steel and carbon steel. The determination results were consistent with the certified values, with relative standard deviations in range of 0.68 %-1.3 %.