https://hdl.handle.net/10259/7463 Wed, 29 Apr 2026 14:19:12 GMT 2026-04-29T14:19:12Z 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. Sat, 01 Mar 2025 00:00:00 GMT https://hdl.handle.net/10259/10043 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. Mon, 01 Jan 2024 00:00:00 GMT https://hdl.handle.net/10259/10026 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%. Sun, 01 Jan 2023 00:00:00 GMT https://hdl.handle.net/10259/10024 2023-01-01T00:00:00Z https://hdl.handle.net/10259/9291 Simultaneous determination of 4-ethylphenol and 4-ethylguaicol on C60 modified dual screen-printed electrochemical sensors Portugal Gómez, Paula; Alonso Lomillo, Mª Asunción; Domínguez Renedo, Olga 4-ethylphenol and 4-ethylguaicol levels in wine are associated to organoleptic defects that cause consumer rejection accompanied by significant economic losses for producers. Thus, electrochemical sensors based on screen-printed carbon electrodes (SPCEs) modified with activated fullerene C60 (AC60) have been developed for the analysis of both phenols by direct headspace amperometric measurements. Upon optimization of the experimental variables affecting the sensors performance, the AC60/SPCE sensors presented linearity ranges from 9.9 to 65.4 μg/L and from 19.6 to 107.1 μg/L for 4-ethylphenol and 4-ethylguaicol, respectively. The achieved detection capacities were 10.3 μg/L (4-ethylphenol) and 19.6 μg/L (4-ethylguaicol), with a reproducibility of 6.3 % and 9.1 % (n = 3), respectively. In addition, dual-working AC60/SPCE devices were developed for the simultaneous analysis of both phenols using different working potentials for each electrode. The dual systems were successfully applied in the analysis of different spiked wine samples, obtaining good recoveries ranging from 94 to 108 %. Mon, 01 Apr 2024 00:00:00 GMT https://hdl.handle.net/10259/9291 2024-04-01T00:00:00Z