The authors describe a voltammetric method for the simultaneous determination of acetaminophen (ACOP) and caffeine (CAF) using a glassy carbon electrode modified with a Nafion® protected halloysite nanotubular clay (GCE). Enhanced electrocatalytic oxidation behavior was observed at pH 4.5 in acetate buffer medium, with oxidation peak potentials of + 0.21 V for ACOP and + 1.0 V for CAF. The peak potential window (~ 800 mV) is quite large and hence differential pulse voltammetry (DPV) can be applied for simultaneous determination of both analytes. The calibration plots of ACOP and CAF are linear in the concentration ranges from 0.6 μM to 14 μM and 0.6 μM to 20 μM, and the detection limits are 1.1 × 10−8 M and 1.73 × 10−7 M, for ACOP and CAF, respectively. The method was applied to the determination of both analytes in drug formulations and human urine samples. [Figure not available: see fulltext.].
