Enzymic determination of inorganic phosphate in the presence of creatine phosphate

A method is presented for the enzymic determination of inorganic phosphate in the presence of labile organic phosphates. The procedure, based on the reaction of glyceraldehydephosphate dehydrogenase, is simple and accurate over a wide range of phosphate concentrations. Commercially available reagents can be used for the assay without purification, making the method suitable for routine use. Methods are also described for extraction of inorganic phosphate from tissues without significant hydrolysis of labile phosphate esters.