Determination of sulfur compounds in petroleum distilates by voltammetry using bismuth electrode

Abstract

This research describes a trace level sulfur determination in petroleum distillated using voltammetry technique. A bismuth electrode was a working electrode. To obtain an optimal conditions for bismuth modified electrode, the influences of bismuth concentration, deposition potential and time on the analyte signal were investigated. The result shown that the bismuth modified electrode was best prepared by electrodeposition of 0.5 ppm bismuth onto the glassy carbon electrode (GCE) at -1.2 V vs. Ag/AgCl for 60 s. The electrode surface was, then, characterized by SEM. Under optimal conditions, the in situ and ex situ bismuth electrode were examined. The in situ bismuth electrode displayed linear dynamic range of 49.9 – 248.8 nM and 2.5 -20 µM for Ph-S-S-Ph and Bu-SH, respectively. While, the ex situ bismuth electrode showed linear dynamic range of 25.0 – 149.5 nM for Ph-S-S-Ph and 2.5 -20 µM for Bu-SH. Detection limit of 19.1 and 12.5 nM were found for the Ph-S-S-Ph and 1.2 and 1.4 µM for Bu-SH, respectively. Finally, the bismuth electrode was applied for kerosene and jet fuel for analysis of Ph-S-S-Ph and Bu-SH. The analysis reviewed that jet fuel and kerosene contain Ph-S-S-Ph and Bu-SH at 230.4 ± 0.1, 102.9 ± 0.1 nM, 12.2 ± 0.3 and 5.2 ± 0.3 µM, respectively.