Sensitive Potentiometric Determination of Amphetamine with an All-Solid-State Micro Ion-Selective Electrode

Abstract

ABSTRACTThe development of amphetamine-ion-selective microelectrodes using electrochemical polymerization and microfabrication technologies is reported in this study. The microelectrodes include polypyrrole films electrochemically polymerized and doped with cosane anion ([3,3′-Co(1,2-C2B9H11)2]−) as the internal solid contact layer between the polymeric sensitive membrane and platinum working microelectrode. Several poly(vinyl chloride)-type membranes with different compositions of plasticizers/ionophore were drop casted on the conducting polymer layer, polypyrrole[3,3′-Co(1,2-C2B9H11)2]. Potentiometric measurements were performed to calibrate the response of the developed chemical sensors. The sensor was highly sensitive to amphetamine using a membrane composition of 26 wt% poly (vinyl chloride), 63 wt% di-butyl phthalate, 6 wt% sodium tetraphenylborate, and 5 wt% dibenzo-18-crown 6-ether. A high and linear response was demonstrated within the concentration range from 10−5 to 10−3 M with a slope of 53 mV/decade and a limit of detection of 4 × 10−5 M. A Reilley diagram shows that the sensor signal is stable for a working pH between 1.50 and 8.50. The chemical sensor was highly selective to amphetamine when compared to other interfering ions and compounds including K+, Na+, , D,L-phenylalanine, caffeine, (±)-epinephrine bitartrate salt, and N-formylamphetamine using the fixed interference method with coefficients of selectivity (Log ) from −1.40 to −1.15.