https://hdl.handle.net/10259/7463 2026-05-17T05:23:25Z https://hdl.handle.net/10259/11598 Gas sensor for 4-ethylguaiacol detection based on tyrosinase enzymatic activity in a deep eutectic solvent Portugal Gómez, Paula; Svigelj, Rossella; Zanette, Fabiola; Toniolo, Rosanna; Domínguez Renedo, Olga; Alonso Lomillo, Mª Asunción The use of environmentally friendly, cost-effective and biodegradable deep eutectic solvents (DESs) as nonaqueous solvents and electrolytes offers a promising avenue for enhancing enzymatic sensors and extending their applicability to the gas phase. In this study, an assembly is presented that includes a paper crown modified with tyrosinase enzyme, soaked in a DES and positioned on a disposable screen-printed carbon electrode. The paper crown contacts the outer edge of the carbon disk working electrode, as well as the peripheral counter and reference electrodes. This assembly yields a portable and disposable electrochemical platform, effortlessly immobilising DESs onto a porous and economical supporting material like paper. Moreover, the entire configuration resulted in a sensitive, rapidly responsive, membrane-free gas sensor whose response time depended exclusively on the enzymatic reaction. The electroanalytical capabilities of this setup were evaluated through voltammetric and amperometric determinations of phenols in synthetic and real wine samples. The proposed gas enzymatic sensor demonstrated excellent analytical performance for detecting phenolic compounds, offering fast measurement times, simple operation, high sensitivity, wide linear range and good repeatability. 2025-05-01T00:00:00Z https://hdl.handle.net/10259/10043 Gold nanoparticle-based amperometric sensors integrating a gel polymer membrane electrolyte for the headspace determination of ethanethiol in wines Molinero Abad, Begoña; Trachioti, Maria; Prodromidis, Mamas I.; Domínguez Renedo, Olga; Alonso Lomillo, Mª Asunción The evaluation of different gold nanoparticles (AuNPs) modified screen-printed carbon electrodes (SPCEs) for the determination of ethanethiol in wine is presented in this work. Two procedures, electrochemical and spark discharge modification, have been tested for depositing AuNPs onto the working electrode surface. A gel polymer membrane, based on the mixture of 1-n‑butyl‑3-methylimidazolium hexafluorophosphate (BMIM-PF6) and poly(vinylidene fluoride) (PVDF) in dimethyl sulfoxide, has been incorporated as a supporting electrolyte for the amperometric determination of the analyte in the gas phase. The developed sensors demonstrated high selectivity and sensitivity, having a detection capability of 80 μg/L (α = β = 0.05). They also exhibited a high degree of precision, with reproducibility values ranging from 0.3 to 7.6%. The different AuNP/SPCEs integrating a gel polymer membrane electrolyte have been successfully applied to the headspace amperometric determination of ethanethiol in various wine samples. 2025-03-01T00:00:00Z https://hdl.handle.net/10259/10026 Gel polymer electrolyte-based dual screen-printed electrodes for the headspace quantification of 4-ethylphenol and ethanethiol simultaneously in wines Portugal Gómez, Paula; Domínguez Renedo, Olga; Alonso Lomillo, Mª Asunción The identification and correction of negative factors, such as 4-ethylphenol and ethanethiol, is important to comply with food safety regulations and avoid economic losses to wineries. A simple amperometric measurement procedure that facilitates the simultaneous quantification of both compounds in the gas phase has been developed using fullerene and cobalt (II) phthalocyanine-modified dual screen-printed electrodes coated with a room temperature ionic liquid-based gel polymer electrolyte. The replacement of the typical aqueous supporting electrolyte by low-volatility ones improves both operational and storage lifetime. Under the optimum conditions of the experimental variables, Britton Robinson buffer pH 5 and applied potentials of + 0.86 V and + 0.40 V for each working electrode (vs. Ag ref. electrode), reproducibility values of 7.6% (n = 3) for 4-ethylphenol and 6.6% (n = 3) for ethanethiol were obtained, as well as capability of detection values of 23.8 μg/L and decision limits of 1.3 μg/L and 9.2 μg/L (α = β = 0.05), respectively. These dual electrochemical devices have successfully been applied to the headspace detection of both compounds in white and red wines, showing their potential to be routinely used for rapid analysis control in wineries. 2024-01-01T00:00:00Z https://hdl.handle.net/10259/10024 Molecularly imprinted polypyrrole based electrochemical sensor for selective determination of ethanethiol Alonso Lomillo, Mª Asunción; Domínguez Renedo, Olga This work describes a molecularly imprinted (MIP) sensor, based on the electropolymerization of pyrrole on a glassy carbon electrode (GCE), for the determination of ethanethiol. Ethanethiol was used as a template molecule for the formation of cavities in the imprinted polymer. The effect of molar ratios template molecules/functional monomers and time needed to remove the template were optimized. The developed MIP/GCE sensor presented a linear range from 6.1 to 32.4 mg L−1 with capability detection and reproducibility values of 7.2 mg L−1 and 10.4%, respectively. The sensitivity of the developed sensor was enhanced by the incorporation of gold nanoparticles (AuNPs). The AuNPs/MIP/GCE showed a capability of detection and reproducibility values of 0.4 mg L−1 and 4.1%, respectively (calibration range from 0.3 to 3.1 mg L−1). The sensor was successfully applied to the determination of ethanethiol in spiked wine samples with recoveries ranging from 99% to 107%. 2023-01-01T00:00:00Z