MICROCOATED WIRE SENSORS FOR THE DETERMINATION OF ANTICANCER DRUGS CYCLOPHOSPHAMIDE AND IFOSPHAMIDE IN THE PRESENCE OF THEIR DEGRADATES

The construction and electrochemical response characteristics of poly (vinyl chloride) and poly (vinyl chloride) carboxylate membrane sensor s for the determination of cyclophosphamide and ifosphamide are descri bed. Based on the formation of an ion-pair complex between the drug ca tion and sodium tetraphenylborate, two poly (vinyl chloride) sensors, namely a cyclophosphamide membrane sensor and ifosphamide membrane sen sor were fabricated. They show a linear response for both drugs over t he concentration range 10(-2)-10(-4) M with cationic slopes of 56 and 51.6 mV per concentration decade, for sensor 1 and sensor 2, respectiv ely. Based on the interaction between the drug solution and the dissoc iated COOH groups in the poly (vinyl chloride) carboxylate, sensor 3 w as fabricated. It shows a linear response for both drugs over the conc entration range 10(-3)-10(-5) M with a cationic slope of 49.7 mV per c oncentration decade. The direct potentiometric determination of cyclop hosphamide and ifosphamide in their pharmaceutical preparations using the proposed sensors gave average recoveries of 101.3 +/- 0.6, 100.8 /- 10.7 and 102.0 +/- 11.0% for the sensors 1, 2 and 3, respectively, which compares reasonably well with the data obtained using the Britis h Pharmacopoeial method (1993). Sensors 1 and 2 were also used to foll ow up the stability of the drugs studied in the presence of their degr adates. These degradation products have no diverse effect on the respo nses of sensors 1 and 2. (C) 1998 Elsevier Science B.V. All rights res erved.