DIPYRIDAMOLE PLASTIC MEMBRANE ELECTRODES BASED ON INDIVIDUAL AND MIXED ION-EXCHANGERS OF DIPYRIDAMOLIUM PHOSPHOTUNGSTATE AND TETRAPHENYLBORATE

Dipyridamole (Dp) selective PVC membrane based on dipyridamolium phosp hotungstate(Dp-PTA), dipyridamolium tetraphenylborate (Dp-TPB) and a m ixture of both (Dp-PTA/TPB) were prepared. Thr electrodes displayed a linear response over the concentration range 6.3 x 10(-6) -1.0 x 10(-1 ) mol dm(-3) dipyridamole hydrochloride (DpCl) The working pH ranges o f the above electrodes were 2.0-7.5, 2.0-7.5 and 2.0-7.0 and their iso thermal coefficients were 0.00096, 0.00010 and 0.00144 V/degrees C, re spectively. The electrodes showed good selectivity to DpCl with respec t ro many inorganic cations, sugars and amino acids. Potentiometric ti tration and standard additions methods were used to determine DpCl in pure solutions and in pharmaceutical preparations with high accuracy a nd precision.