Enhanced detection of trace sulfur levels in gasoline by bismuth electrode using square wave voltammetry

Abstract

This study introduces a simple, cost-effective, and rapid bismuth electrode-square-wave voltammetry method for determining the total sulfur content in automotive gasoline. Optimal conditions for the developed electrode, including various Bi ion concentrations, deposition times, and potentials, were established on a glassy carbon electrode. The results demonstrated that the highest response was achieved when the bismuth electrode was placed in an acetate buffer and a methanol:toluene (1:1 v/v) solvent. The method was validated with and without a 30-second electro-preconcentration step. The voltammetric method in conjunction with the preconcentration step exhibited a sensitivity of 571.81 nA mg L⁻¹, a limit of detection (LOD) of 0.02 mg L⁻¹, and a limit of quantification (LOQ) of 0.08 mg L⁻¹. Without the preconcentration step, the method yielded a sensitivity of 421.89 nA mg L⁻¹, an LOD of 0.03 mg L⁻¹, and an LOQ of 0.11 mg L⁻¹. The developed method was applied to quantify commercial fuel samples. The results showed that the electrochemical technique yielded a similar total sulfur content to that measured by the standard ASTM D2622 method, with an error of less than 7.5%. Moreover, the method proposed in this study had lower LOD and LOQ limits, meeting the EURO5 and EURO6 regulations.

GRAPHICAL ABSTRACT

KEYWORDS:

• Sulfur
• fuel
• square-wave voltammetry
• gasoline
• bismuth electrode

Acknowledgments

The financial support was obtained from Thailand Research Fund Grant MRG5180230 and the 90th Anniversary of Chulalongkorn University Fund, Thailand. The authors extend their appreciation to the Researchers Supporting Project number (RSPD2024R944), King Saud University, Riyadh, Saudi Arabia for funding this work. We are greatly thankful for automotive fuel samples including their ASTM D2622 data supported by the Department of Energy Business, Ministry of Energy, Thailand.

Disclosure statement

No potential conflict of interest was reported by the author(s).