Determination of phosphate: Study of labile organic phosphate interference

An investigation was carried out on a newer method for the determination of inorganic phosphate which is applicable to the study of phosphate-splitting enzymes. It offers a unique advantage: after the color reagent has been added any inorganic phosphate formed cannot react with molybdenum, for the latter has been complexed by the addition of a citrate-arsenite solution and phosphate cannot compete successfully for the molybdate. This procedure appears to be quite suitable for the determination of inorganic phosphate, phospholipids, nucleotides or enzyme-hydrolyzed phosphate.