用2-(对磺基苯偶氮)变色酸胶束增溶光度法测定微量镁

Spectrophotometric Determination of Magnesium in the pressence of Mixed Sufactants by p-Sulfophenylazo Chromotropic Acid

在混合表面活性剂（CPB＋OP）存在下，镁（Ⅱ）和2－（对磺基苯偶氮）变色酸（SPADNS）的络合反应发生显著的增敏作用，其λmax为606nm，比无混合表面活性剂时红移33nm，灵敏度提高近11倍，表观摩尔吸光系数（ε'）达1．23×105·mol-1·cm－1.测量的pH范围为10．0～11．3，镁浓度在0～200μg／L内符合比尔定律．Fe3＋、Al3＋等干扰离子可用TEA－甘露醇联合掩蔽。用拟定的方法测定了铝合金中的镁，结果满意．

p-Sulfophenylazo chromotropic acid reacts with magnesium in the presence of mixed surfactants (CPB+OP) to form a water soluble blue chelate. The optimum pH for the reaction is in the range of 10. 1~ 11. 3. The apparent molar absorption coeffient is 1. 23× 105 L. mol ~1. cm -1. By the addition of TEA-mannitol as masking reagents, better selectiv ity is achieved, and the method proposed can be applied to the determination of magnesium in the aluminium alloy with satisfactory results.