| Abstrakt: |
Thymol and carvacrol (isopropylmethylphenols) are natural phenolic monoterpenoids with antibacterial, antifungal, insecticidal, and antioxidant properties. Their dose-dependent antioxidant effect requires control in real samples. Various modes of voltammetry have been successfully developed for thymol and carvacrol quantification. A glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and electropolymerized thymolphthalein has been developed for this purpose. The conditions of thymolphthalein electropolymerization (monomer concentration, number of cycles, and parameters of electrolysis) providing the best response to thymol have been found. The scanning electron microscopy and electrochemical methods confirm the effectivity of the sensor developed. In differential pulse mode, the sensor gives a linear response in the ranges of 0.050–25 and 25–100 μM for thymol and 0.10–10 and 10–100 μM for carvacrol, with detection limits of 0.037 and 0.063 μM, respectively, that are significantly improved compared to those reported earlier. The sensor developed is selective to isopropylmethylphenols in the presence of typical interferences (inorganic ions, saccharides, and ascorbic acid) and other phenolics (caffeic, chlorogenic, gallic and rosmarinic acids, quercetin, and rutin). A sensor has been applied for the evaluation of total isopropylmethylphenols in oregano and thyme spices using single sonication-assisted extraction with methanol. The voltammetric sensor data agreed well with the independent spectrophotometric quantification. [ABSTRACT FROM AUTHOR] |
