HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC CHARACTERIZATION OF MONOFLUOROPHOSPHATE, DIFLUOROPHOSPHATE AND HEXAFLUOROPHOSPHATE

The retention behaviour of fluorophosphates on an anion-exchange colum n was characterized and compared with that of phosphates. Postcolumn b lue coloration of phosphorus with a molybdenum reagent allowed the sen sitive detection of both fluorophosphates and phosphates. P-31 NMR mea surements were also employed to provide complementary data for the ide ntification of phosphorus compounds. The retention times of orthophosp hate and its fluorine derivatives increased with increasing number of P-F bonds: PO43- < PO3F2- < PO2F2- < PF6-. Good separation among ortho phosphate, monofluorophosphate and difluorophosphate was achieved, but hexafluorophosphate was adsorbed too strongly to be eluted. It is sug gested that fluorine derivatives of diphosphate (pyrophosphate), P2O6F 3- and P2O5F22-, might be present as minor impurities in monofluoropho sphate chemicals. A misleading suggestion as to the assignment of unkn own peaks in a preliminary report was corrected. Retention times with elution using 0.18 M KCl of the authentic phosphates and fluorophospha tes and the speculated diphosphate derivatives increased in the order PO43- < PO3F2- < P2O74- < P2O6F3- < P3O105- < PO2F2- < P2O5F22- < P3O9 3- < PF6-.