MEMBRANE SENSORS FOR THE SELECTIVE DETERMINATION OF FLUOROURACIL

The construction and electrochemical response characteristics of poly( vinyl chloride) matrix membrane sensors for fluorouracil are described . The membranes incorporate ion association complexes of fluorouracil anion with bathophenanthroline-nickel(II) [sensor I], bathophenanthrol ine-iron(II) [sensor 2] and phenanthroline-iron(II) [sensor 3] as elec troactive materials. These sensors show linear response for fluorourac il over the range 1.3-130 mu g ml(-1), with anionic slopes of 29.0, 27 .9 and 34.3 mV per concentration decade with sensors 1, 2 and 3, respe ctively These sensors exhibit fast response time (1.0-1.5 min), low de termination limit(1x10(-5) M), good stability (4-8 weeks) and reasonab le selectivity. The sensors were used for direct potentiometry and pot entiometric titration of fluorouracil in some pharmaceutical preparati ons. Results with mean accuracy of 98.6+/-0.9% of nominal were obtaine d which compare well with data obtained using the British Pharmacopoei al method. The sensors were also used to follow the stability of the d rug in the presence of its degradates, namely formaldehyde, fluoroacet ate and urea. In the presence of glycine, these products have no effec t on the responses of the sensors. (C) 1998 Elsevier Science B.V.