Development of polymer-membrane based electrodes for suramin

The development of a polymer membrane-based electrode to measure the anionic drug suramin in buffered saline and biological samples is described. A large non-equilibrium, steady state EMF response is observed toward suramin, and judicious choice of the polymer membrane components allows for adjustment of the dynamic range of the electrode. The optimized membrane for use in the toxic suramin range consists of 25 wt% tridodecylmethyl ammonium chloride, 55 wt% bis-2-ethylhexyl sebacate, and 20 wt% Pellethane. Although this electrode can be used to directly quantify suramin in human plasma, determination of suramin that is not affected by the background concentration of small anions is best achieved by simple potentiometric titrations with polycationic protamine monitored with a protamine-sensitive electrode.