The enthalpimetric determination of mixtures containing phosphate,arsenate(V) and arsenate(III) ions

A series of mixtures, each containing at least two of the ions phosphate, arsenate(V) and arsenate(III) have been determined enthalpimetrically using the concept of the additivity of partial molar heat pulses. The non-selective reactions used involved precipitation and redox reactions. The accuracy at the 1mM level is within 1.5%, and the total time of a determination of a mixture of all three anions is less than 10 minutes after preparation of the sample solution, which is prepared for insoluble phosphates, by metathesis with sodium carbonate.