Quantification of paracetamol with square wave voltammetry

Importance of the Topic

Square wave voltammetry provides a highly sensitive and rapid tool for detecting pharmaceutical compounds such as paracetamol. Its capability to isolate faradaic currents from background noise improves resolution and lowers detection limits, making it essential for pharmaceutical quality control and environmental monitoring.

Objectives and Study Overview

This study demonstrates the use of unmodified screen-printed electrodes combined with INTELLO VIONIC potentiostat to quantify paracetamol in aqueous solutions. Key goals include investigating electrochemical behavior under optimized conditions, establishing a calibration curve, and evaluating method sensitivity, reproducibility, and robustness against interferences.

Methodology and Instrumentation

Solutions of 4-acetamidophenol were prepared in 0.1 M TRIS HCl buffer adjusted to pH 8–9. Standard concentrations ranged from 1×10-6 to 1×10-3 mol/L. A crushed tablet sample was dissolved and diluted within the linear range. Cyclic voltammetry identified oxidation behavior at different pH values. Square wave voltammetry parameters were optimized as follows:

• Amplitude: 80 mV
• Frequency: 15 Hz
• Step height: 5 mV
• Potential range: ‑0.2 V to 1.3 V vs AgCl

Used Instrumentation

The sensor was a DRP-C110 screen-printed electrode with carbon working and counter electrodes and an Ag reference electrode. Electrochemical measurements were performed using the VIONIC potentiostat powered by INTELLO software.

Main Results and Discussion

Cyclic voltammetry at pH 6–7 showed an irreversible two-electron oxidation of paracetamol with no reverse peak, while at pH 8–9 the oxidation became quasi-reversible with a measurable reduction peak. The optimized SWV method produced a linear calibration curve (y = 58695x + 1.9823) over the tested concentration range. Analysis of the tablet sample yielded a peak current of ~31 µA, corresponding to a paracetamol content of approximately 430 mg compared with the labeled 500 mg.

Benefits and Practical Applications

The described approach offers:

• High sensitivity and low detection limits suitable for trace analysis
• Rapid and reproducible measurements using disposable electrodes
• Cost-effective setup for routine pharmaceutical and environmental testing

Future Trends and Applications

Further developments may include integration of portable or field-deployable devices, multi-analyte detection arrays, advanced electrode materials for enhanced selectivity, and the incorporation of data analytics or machine learning for real-time monitoring and decision support.

Conclusion

Square wave voltammetry with unmodified screen-printed electrodes and INTELLO VIONIC potentiostat enables rapid, accurate, and cost-effective quantification of paracetamol. The method shows strong agreement with labeled values and is well suited for pharmaceutical quality control and environmental analysis.

Reference

• Hart NT Lane WC de la Garza L Electrochemical Quantification of Acetaminophen An Engaging Cyclic Voltammetry Laboratory for the Quantitative Analysis Course J Chem Educ 2020 97(8) 2254–2259