UTILIZATION OF A SILICA-MODIFIED CARBON PASTE ELECTRODE FOR THE DIRECT DETERMINATION OF TODRALAZINE IN BIOLOGICAL-FLUIDS

Todralazine [ethyl 2-(-l-phthalazinyl)hydrazinecarboxylate] was determined by using a carbon paste electrode modified with silica. Todralazine is adsorbed on the electrode and determined in 0.1 mol 1-1 KNO3 (pH 1.8) by differential-pulse voltammetry. The adsorption can be carried out in open circuit or by applying a fixed potential (0.8 V vs. Ag/AgCl). The detection limits are about 4 x 10(-7) and 3 x 10(-8) mol l-1, respectively. The method can be applied to the determination of todralazine in human urine. It is possible to determine directly 2.3 mug ml-1 of todralazine in urine with a relative standard deviation of 1.1% (n = 5)