Abstract
Hummel-Dreyer’s method was examined for its applicability to inorganic complexes, and a modified method was proposed. A sample solution containing magnesium and diphosphate was eluted with magnesium chloride solution on a gel column. The change of magnesium concentration in an effluent was measured with an atomic absorption detector. From the peak area of the eluted complex the stability constants (1g β1) at I=0.1 and 25 °C were evaluated to be 5.57 in tetramethylammonium chloride solution and 5.06 in sodium perchlorate solution. In the modified method the total magnesium concentration in a sample solution is made to be much higher than that in an eluent. This enables one to shorten the elution time.