Latest publication – CSOB and ERMMES group

Voltammetric techniques for low-cost on-site routine analysis of thymol
in the medicinal plant Ocimum gratissimum

The composition of essential oils varies according to culture conditions and climate, which induces a need for simple and inexpensive characterization methods close to the place of extraction. This appears particularly important for developing countries. Herein, we develop an analytical strategy to determine the thymol content in Ocimum Gratissimum, a medicinal plant from Benin. The protocol is based on electrochemical techniques (cyclic and square wave voltammetry) implemented with a low cost potentiostat. Thymol is a phenol derivative and was directly oxidized at the electrode surface. We had to resort to submillimolar concentrations (25–300 μM) in order to minimize production of phenol oligomers that passivate the electrode. We worked first on two essential oils and realized that in one of them the thymol concentration was below our detection method. These results were confirmed by gas chromatography – mass spectrometry. Furthermore, we optimized the detection protocol to analyze an infusion made directly from the leaves of the plant. Finally, we studied whether the cost of the electrochemical cell may also be minimized by using pencil lead as working and counter electrodes.

Latifou Lagnika, Solange Imelda Avosse, Faridath Oyélékan Bouraima, Candide Bidossessi Sindedji, Mathieu Dakle, Rodolphe Gueret, Laure Fort, Yves Gimbert, Teko W. Napporn, Dodzi Zigah, Agnès Aubouy, Emmanuel Maisonhaute

Talanta 269 (2024) 125411
hal-04313217 , version 1