Amphetamine Selective Electrodes Based on Dibenzo-18-crown-6 and Dibenzo-24-crown-8 Liquid Membranes

Abstract

Two novel membrane electrodes highly sensitive and selective for amphetaminium cation are developed and electrochemically evaluated according to IUPAC recommendations. These electrodes Incorporate amphetamine-dibenzo-18-crown-6 (DB18C6) and amphetamine-dibenzo-24-crown-8 (DB24C8) as the active components in 1,2-dichloroethane solvent. Both electrode systems exhibit stable near-Nemstian response over the range 10-2-10-5 M amphetaminium cation with a slope in the range of 55–58 mV/decade of concentration. The working pH range is 3–7, the response time varies from 30 to 50 s and the lower limit of detection is ∼3 ppm. The selectivity toward amphetaminium cation is reasonably high relative to many common inorganic cations and alkaloids as well as some amines structurally related to amphetamine. The DB18C6 membrane is 2–14 times more selective for amphetamine in the presence of foreign compounds than DB24C8 based electrode. Determination of 5 μg mL-1 to 4 mg mL-1 of amphetamine sulfate using the standard addition (spiking) technique shows an average recovery of 98.7% and a mean standard deviation of 1.7%. The method offers several advantages over the standard procedures. © 1989, American Chemical Society. All rights reserved.