Electrochemical Quantification of Acetaminophen: An Engaging Cyclic Voltammetry Laboratory for the Quantitative Analysis Course

Abstract

An engaging, simple, and cost-effective laboratory experiment has been implemented at our institution to teach undergraduate chemistry students about cyclic voltammetry and electrochemistry in general. This experiment involves the application of cyclic voltammetry to analyze a sample of acetaminophen (APAP) with the objective of determining the mass of APAP in a tablet of over-the-counter medication. During five semesters, students working in groups of typically four students each, carried out the experiment as part of their coursework in the laboratory. Seven out of ten groups reported results containing the expected value of 500 mg APAP per tablet in their calculated 95% confidence intervals. Students completed a 10-question quiz at the beginning of the semester and a similar one at the end of the semester. The scores of preand postcourse evaluations, which include 10 questions on basic general chemistry quantitative concepts, had an average percent change of 99.2% after, from a 50.7% average percent change before, laboratory implementation. The growth in normalized learning gains in classes performing this experiment also increased by 10.8%.

PassStat, a simple but fast, precise and versatile open source potentiostat

“…Here, paracetamol concentration was 1 mM and we choose 0.10 M citric acid as supporting electrolyte. Many different conditions are described in the literature [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , and we found that an acid medium provided a better reproducibility. Moreover, citric acid can be purchased easily so that preparing this electrolyte may be easier than other classical buffers in non-ideal experimental conditions.…”

“…We then present representative results obtained in cyclic voltammetry or square wave voltammetry. We took ferrocene as common reference electroactive entity, and paracetamol as typical example of drug analysis application [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] . We named our potentiostat the PassStat, after the French electrochemical YouTube video series “Le Courant Passe” produced by the Societe Chimique de France to catch student interest [26] .…”

Synthesis and Characterization of a Metal-Free Organic Dye-Sensitizer for Solar Cell: An Advanced Organic Chemistry Research-Based Laboratory

“…The HOMO and LUMO energies can be estimated from the cyclic voltammetry according to Koopman’s theorem where the first oxidation potential corresponds to the HOMO, and the reduction potential to the LUMO energies . In order to measure the first oxidation potential ( E ox ) corresponding to the HOMO of the synthesized dye, students collected the cyclic voltammograms in CH 2 CI 2 and performed an in-depth analysis of the electronic and redox properties of the organic dye-sensitizer. − The cyclic voltammogram of 4 in CH 2 CI 2 exhibits an irreversible reduction peak at −1.80 V vs NHE, and a quasi-reversible oxidation peak at 1.34 V and an irreversible oxidation peak at 1.84 V vs NHE (Figure ). − The HOMO and LUMO energy levels of 4 are presented in Figure by comparing them to the redox potential of the electrolyte, and to the conduction band of TiO 2 , respectively.…”

“…After obtaining the final compound, students collect the absorption and fluorescence spectra of the dye using UV–vis and fluorescence spectrophotometers, respectively. The cyclic voltammograms are collected to determine the oxidation potentials ( E ox ) of the dye. − The cyclic voltammetry measurements were performed using a BASi Epsilon system in a cell stand using a potentiostat with three electrodes: Pt working electrode, platinum wire as an auxiliary electrode, and nonaqueous AgNO 3 /Ag electrode as the reference. Tetrabutylammonium perchlorate (TBAP) was used as an electrolyte.…”

Beyond the Textbook: Introducing Undergraduates to Practical Electrochemistry

“…With such modification, groups of 2–3 students could each be responsible for data collection with their own potentiostat and electrodes. We refer the interested reader to some of the many recent advances in course-based, inquiry-focused implementations of electrochemistry, − electrochemical hardware, − and electrodes , and plan several such undertakings ourselves.…”