“…Several published methods for the determination of triphosphate and pyrophosphate involve the use of zinc ions for the precipitation of one or both of these phosphates (3, 4, 6, 7, 16,19,26,27,31). In some of the supporting experiments on which the methods are based, and in the studies of condensed phosphate precipitations by other metal ions such as manganese(II) (17), and tris(ethylenediamine) cobalt(III) (21), there is evidence that pyrophosphate and triphosphate are harder to separate from each other than orthophosphate or trimetaphosphate.…”