POLYPHOSPHATE SEPARATIONS AND CHAIN-LENGTH CHARACTERIZATION USING MINIBORE ION CHROMATOGRAPHY WITH CONDUCTIVITY DETECTION

The separation of linear and cyclic polyphosphates with chain lengths of 1 to ca. 30, using 2 mm I.D. polymeric ion-exchange columns and suppressed conductivity detection, is described. The separations are characterized by good resolution of phosphate species and analysis times <30 min. To assess the accuracy of the chromatograms obtained, average chain lengths of sodium hexametaphosphate and glassy phosphates in the range 5-25 are determined and compared with results obtained by P-31 NMR and potentiometric titration. General agreement among the three techniques is seen. An example is presented using ion chromatography to follow the hydrolysis of sodium hexametaphosphate.