Construction and performance characteristics of new fentanyl-selective plastic membrane electrode

The construction and performance characteristics of an ion-selective electr ode for fentanyl-drug cation, based on an ion-pair complex with tetrakis[3, 5-bis-(trifluoromethyl)phenyl]borate anion in a PVC matrix were studied. A linear response for 1 x 10(-5) mol dm(-3) to 1 x 10(-2) mol dm(-3) drug wit h a slope of 57.9 +/- 0.5 mV/decade was established. The optimum pH range w as 2 to 6. The lower detection limit was 6.29 x 10(-6) mol dm(-3) fentanyl citrate (2.1165 mug cm(-3) fentanyl). There were negligible interferences f rom a number of inorganic cations, structural analogues, and some common dr ug additives in injections. The electrode proposed has been successfully ap plied to determine fentanyl citrate in injections. The results correlated w ell with those obtained by the United States Pharmacopoeia standard procedu re.