Fabrication, Characterization and Performance Evaluation of Screen-printed Carbon Electrodes: Determination of Acetaminophen in Tylenol

Abstract

Screen-printed carbon electrodes (SPCEs) were fabricated and compared with the commercial DS 110 (DropSens). In addition to the classic cyclic voltammetry (CV) of K 3 [Fe(CN) 6 ], a method using widely available Bausch + Lomb and Tylenol was developed for comprehensive evaluation of the electrochemical performance of SPCEs. Scanning electron microscope (SEM) images showed that the graphite surface of the in-house SPCEs, which acted as reaction surface, was covered by grainy binders thus less reactive than DS 110. X-ray photoelectron (XPS) spectra indicated that both were composed primarily of graphite (> 85%), but the concentrations of S (detected in DS110 only), N and Cl in the less-electroactive binders differed. The CV using K 3 [Fe(CN) 6 ] as probe revealed that the peak-to-peak separation of the in-house SPCE (0.140 V) was further apart than that of DS 110 (0.075 V). The oxidation and reduction peak currents of the in-house SPCE were 73% and 82% of that of the DS 110, respectively. When CV was applied to the determination of acetaminophen in Tylenol (product label concentration: 661 mmol/L) using Bausch + Lomb solution with 1 mol/L KCl as the buffer, DS 110 showed better sensitivity, but the in-house SPCE was stable and more precise. Though DS 110 displayed higher current and thus more sensitive, the in-house SPCE current was stable and thus more precise. The concentrations obtained from oxidation and reduction peaks were (775 ± 80) mmol/L and (686 ± 322) mmol/L for DS 110, and (637 ± 39) mmol/L and (713 ± 139) mmol/L for in-house SPCE, respectively. Moreover, DS 110 exhibited two large unknown peaks and thus less reliable in the acetaminophen-in-Tylenol CV test. Determination of acetaminophen in real Tylenol sample was helpful as additional quality control in SPCEs fabrication. To evaluate the electrochemical performance of in-house screen-printed electrode (SPCE) and commercial SPCE (DS 110), a fast and inexpensive method to analyze concentration of acetaminophen in Tylenol using Bausch + Lomb as buffer was developed, in addition to the classic K 3 [Fe(CN) 6 ]. The results were relatively accurate. Meanwhile, surface characterizations showed that both SPCEs contained major amount of graphite but with different configurations, which might result in a less sensitivity but more precision of the in-house SPCEs compared to DS110.