Carbon film resistor electrode for amperometric determination of acetaminophen in pharmaceutical formulations

Flow injection analysis (FIA) with amperometric detection was employed for acetaminophen quantification in pharmaceutical formulations using a carbon film resistor electrode. This sensor exhibited sharp and reproducible current peaks for acetaminophen without chemical modification of its surface. A wide linear working range (8.0 × 10−7 to 5.0 × 10−4 mol L−1) in phosphate buffer solution as well as high sensitivity (0.143 A mol−1 L cm−2) and low submicromolar detection limit (1.36 × 10−7 mol L−1) were achieved. The repeatability (R.S.D. for 10 successive injections of 5.0 × 10−6 and 5.0 × 10−5 mol L−1 acetaminophen solutions) was 3.1 and 1.3%, respectively, without any memory effect between injections. The new procedure was applied to the analyses of commercial pharmaceutical products and the results were in good agreement with those obtained utilizing a spectrophotometric method. Consequently, this amperometric method has been shown to be very suitable for quality control analyses and other applications with similar requirements.