Sayed S. Badawy, Marwa El badry Mohamed, Amira M. Shawky

Department of chemistry, Faculty of science, Cairo University, Giza, Egypt.

Summary: Tioconazole modified carbon paste and copper coated wire ion selective electrodes have been prepared, based on the ion pair of tioconazole Tc with sodium tetraphenyl boron (III) Tc-TPB dissolved in dioctyl phthalate DOP as a pasting liquid and plasticizer. The electrodes showed the linear response with mean calibration graph slopes of 57.2 and 54.1 mV/decade, respectively, at 25±1°C; at a concentration range of 1×10^-6 - 1×10^-2 M and 1×10^-6 - 5×10^-3 M, respectively and lower detection limit of 1×10^-6 M. The change of pH of the test solution within the range 2.5 – 4.5 did not affect the electrodes performance. The electrodes showed a very good selectivity toward Tc with respect to a large number of organic and inorganic cations and compounds. The standard addition and potentiometric titration methods were applied for the determination of tioconazole in pure solution and in pharmaceutical preparations with an average recovery range of 98.0% – 101.3% and a mean relative standard deviation (RSD) of 0.12% - 1.35% which were of comparable accuracy and precision to pharmacopeial method.