Todralazme [ethyl 2-61-phthalazmyl)hydrazmecarboxylate] was deternuned by using a carbon paste electrode modified with sibca Todralazme IS adsorbed on the electrode and determmed m 0 1 mol 1-l KNO, (PH 18) by dfierential-pulse voltanunetry The adsorption can be camed out m open cucmt or by applymg a fixed potential (0 8 V vs Ag/AgCl) The detection lumts are about 4 X lo-' and 3 X 10-s mol I-', respectively The method can be apphed to the determmatlon of todralazme m human urme It IS possible to determine dlrextly 2 3 pg ml-' of todralazme m urme wth a relatwe standard dewatlon of 1 1% (n = 5) Keywords Voltammetry, Carbon paste electrodes, Pharmaceutxals, Sduza-modified electrodes, Todralazme, Urme Voltammetrrc determmatlons of pharmaceutlcal products m blologlcal fluids generally need a precedmg extraction process so that the multiple mterferences caused by this complex matrix m classlcal electrodes such as Hg, Pt, Au or C can be ehmmated However, the extraction increases the tune and expense of analysis
Recently, the use of carbon paste electrodes modified Hrlth several adsorbents has been reported [l-4] The advantage of this kmd of electrode 1s that drugs can be determmed 111 blologlcal fluids urlthout pnor separation In general, the most sensitive electroanalytlcal technique IS adsorptlve strlppmg voltammetry, using a static mercury electrode for the reduction process or a carbon paste electrode for the oxldatlon process [5-81 However, not all compounds can be prevlously adsorbed on the electrode surface In order to improve the adsorption capacity of the carbon