Amiodarone-selective membrane electrode

A liquid membrane electrode based on an amiodarone-dipicrylamine ion-pair complex, dissolved in nitrobenzene as solvent, is proposed for the determination of amiodarone, an antiarrhythmic drug. The linear response covers the range 10(-2)-10(-5) M amiodarone solution, with a slope of 57.3 mV/decade (pH range 0.80 to 4.80). The detection limit is 4 x 10(-9) M. The electrode shows a good stability, reproducibility and fast response. The selectivity is good against K+ and Ca2+. There are two strong interfering ions, ephedrine and polyvinylprolidone. The characteristics of the electrode make it useful for the determination of amiodarone by direct and indirect potentiometric methods. Through the indirect potentiometric method, amiodarone can be determined as an active substance with an average recovery of 99.60% and a relative standard deviation of 0.67%, and this method can also be used for its determination in pharmaceutical dosage forms such as tablets and ampoules with a relative standard deviation less than 1%. The electrode can also be used for dissolution tests of amiodarone tablets. The physical processes are numerically simulated by typical equations. The apparent first-order rate constants for disintegration and dissolution processes have been calculated.