A New Potentiometric Sensor for Determination of Pethidine hydrochloride in Ampoules and Urine

A simple, precise, rapid and low-cost potentiometric method for pethidine determination in pharmaceuticals and urine is proposed. A chemically modified carbon paste electrode (CMCPE) for pethidine hydrochloride (PDCl) based on pethidine-phosphotungstate (PD-PT) as ion-pair complex was prepared and fully characterized in terms of composition, usable pH range, response time and temperature. The pethidine electrode showed Nernstain responses in the concentration range 2.1 × 10 1.0 × 10 M with a detection limit of 7.3 × 10 and usable within the pH range 3.5 6.6. This sensor exhibited a fast response time (about 5 8 s), good stability. The value (dE/dt) of the electrode was found to be 0.00071 V/ ̊C, which indicates fairly high thermal stability. Selectivity coefficients determined by matched potential method (MPM) and separate solution method (SSM) showed high selectivity for PDCl with respect to a large number of inorganic cations, organic cations, sugars and some common drug excipients. The sensor could be used successfully in the estimation of PDCl in ampoules and in spiked urine samples.