Перегляд за Автор "Oliveira, Sílvio C."

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The theoretical description for aesculetin and quercetin cathodic electrochemical determination in juice
(2023) Tkach, Volodymyr; Paiva Martins, José Inácio F.; Romanova, Zoriana; Oliveira, Sílvio C.
Douro juice is one of the symbols of Portugal. The Douro wine region was first marked in the 18th century. The juice has its characteristic smell and taste, due to the presence of some aromatic lactones. But the main nutritional value of the juice is given by its polyphenol composition. Chestnut C. Sativa is one of the most important products and ingredient for Trás-os-Montes cuisine. Vila Regions - Research on chestnut chemicals and nutritional composition confirms that this fruit is low in fat, cholesterol-free and gluten-free. On the other hand, it is a rich source of starch (carbohydrates), protein, dietary fiber, vitamins, minerals (such as potassium, phosphorus and magnesium), lipids and nutrients. Therefore, it should be investigated. Сік Дору є одним із символів Португалії. Виноробний регіон Дору був першим позначений у XVIII ст. Сік має свій характерний запах і смак, завдяки наявності деяких ароматичних лактонів. Але основну харчову цінність соку надають за своїм поліфенольним складом каштан C. Sativa є одним із найважливіших продуктів і інгредієнт для кухні Trás-os-Montes. Дослідження хімічних речовин каштану та його поживний склад підтверджує, що цей фрукт містить мало жиру, не містить холестерину та глютену. З іншого боку, це багате джерело крохмалю (вуглеводів), білку, клітковини, вітамінів, мінералів (такі як калій, фосфор і магній), ліпідів та інших поживні речовин. Отже має бути дослідженим.
The theoretical description for aesculetin and quercetin cathodic electrochemical determination in wines
(2023) Tkach, Volodymyr; Paiva Martins, José Inácio F.; Romanova, Zoriana; Paientko, Viktoria; Oliveira, Sílvio C.; Garcia, Jarem; Skrypska, Olha; Ivanushko, Yana; Yagodynets, Petro
In this work, the possibility of cathodical electroanalytical determination of aesculetin and quercetin, the most representative polyphenolic coumarin and flavonoid, is theoretically described. The cathodic reaction is given by the electrochemical reduction of 2- and 4-pyrone rings simultaneously on a vanadium(III) oxyhydroxide-modified electrode at a pH correspondent to wine (3 < pH _ 7). Analysis of the mathematical model, corresponding to the reaction mechanism, lets us conclude that, although the oscillatory behavior remains highly probable, the cathodic electroanalytical process, based on VO(OH)-assisted reaction, may be even more efficient than anodic oxidation of the polyphenolic compounds in the same conditions.
The theoretical description for CoO(OH)-assisted salicylic acid derivatives determination in beer
(2023) Tkach, Volodymyr; Morozova, Tetiana; Kushnir, Marta; Prymachenko, Serhii; Oliveira, Sílvio C.; Yuzkova, Valentyna; Nazymok, Yevgeniya; Banul, Bohdana; Honchar, Tetiana; Garcia, Jarem; Nikitchenko, Liliya; Yagodynets, Petro; Kormosh, Zholt; Palamarek, Karina; Chychun, Valentyna; Bagrii, Konon; Paiva Martins, Jose Inacio Ferrao; Khmeliar, Inesa; Kushnir, Lesya; Sabadyshyn, Rostyslav; Lysytsia, Dmytro; Sharipova, Riboba; Musayeva, Dilfuza; Lavrik, Ruslan; Moroz, Valerii; Hrabovska, Olena; Tkachenko, Lyubov; Khargeliia (Karputina), Daria; Karputina, Margarita; Grekova, Alla; Burdinina, Yanina
In this work, the possibility of the electrochemical determination of salicylic acid on conducting polymer – CoO(OH) composite has been evaluated. The electrooxidation mechanism includes the gradual phenolization of the aromatic ring carbon atoms 3 and(or) 5 with further electrooxidation to the correspondent quinone. The analysis of the correspondent mathematical model utilizing linear stability theory and bifurcation analysis confirms the conducting polymer composite efficiency in salicylic acid determination in a wide concentration range. On the other hand, the oscillatory behavior in this system is possible, but its realization and feature strongly depend on the analyte nature and background electrolyte composition.
The theoretical description for ethanol and hydrpoxyquinol determination in wines and fruit juices
(2022) Tkach, Volodymyr; Kushnir, Marta; Morozova, Tetiana; Oliveira, Sílvio C.; Romaniv, Lyudmyla; Pishak, Olga; Khmeliar, Inesa; Kushnir, Lesya; Romanova, Zoriana; Yagodynets, Petro
Fermentation is the main process, standing in the base of the formation of alcoholic drinks. Various drinks like wine, cider, rum, rumtopf or gin are made by fruit juices fermentation. The glucose fermentation product is ethanol. As for fructose, its fermentation product is hydroxyquinol.
The theoretical description for sotolone cathodic and anodic electrochemical determination in wines
(2023) Tkach, Volodymyr; Kushnir, Marta; Oliveira, Sílvio C.; Garcia, Jarem; Karputina, Margarita; Khargeliia (Karputina), Daria; Ivanushko, Yana; Morozova, Tetiana; Yagodynets, Petro
Sotolone is a natural aromatizer, present in Portuguese wine. The goal of this work is the mechanistic theoretic analysis of the sotolon electrochemical determination over a conducting polymer electrode.
The theoretical description for sulfite vanadium(III)-oxyhydroxide-assisted electrochemical determination in natural water and beverages
(2022) Tkach, Volodymyr; Kushnir, Marta; Oliveira, Sílvio C.; Garcia, Jarem; Ivanushko, Yana; Nazymok, Yevgeniya; Morozova, Tetiana; Yagodynets, Petro; Khmeliar, Inesa; Kushnir, Lesya; Shahiieva, Raisa; Vitriak, Oksana; Romanova, Zoriana; Grabovska, Olena
Sulfite is the ion of sulfurous acid, correspondent to tetravalent sulfur. It is used as a conservant in food industry and in beverage production. On the other hand, sulfite is an ecological marker for acid rains occurrence, which may be highly (eco)toxic, reason why its determination is really actual. Being a tetravalent sulfur derivative, sulfite may be either oxidized or reduced. In the case of cathodic reduction, the elemental sulfur or sulfide-ion may be a product, depending on pH.
The theoretical description of sucralose cathodic electrochemical determination over a poly(safranin) modified electrode in acidic media
(2023) Tkach, Volodymyr; Storoshchuk, Nataliia; Storoshchuk, Bogdan; Oliveira, Sílvio C.; Kryvetskyi, Viktor; Kryvetska, Inna; Kryvetskyi, Igor; Yemelianenko, Nataliia; Narsiia, Valentyn; Yagodynets, Petro; Silva, Adriano; Masna, Zoriana; Shevchenko, Inna; Gnitsevych, Victoriya; Medvedeva, Anzhelika; Vasylieva, Olena; Musayeva, Dilfuza; Kosimov, Xayriddin; Jabborova, Oysha; Samadov, Bakhodirjon; Sagdullayeva, Gulandom; Hamdanova, Gulhayo; Karputina, Margarita; Khargeliia (Karputina), Daria; Garcia, Jarem; Odyntsova, Vira; Martins, José Inácio Ferrão da Paiva
For the first time, sucralose cathodic electrochemical determination, assisted by the safranin-modified electrode in acidic solutions, has been theoretically described. The correspondent mathematical model analysis has shown that the steady-state stability range is wider than in most systems of electrochemical determination over the pyridinic nitrogen-containing conducting polymer. Moreover, the oscillatory behavior is less probable than in similar systems in acidic media. Nevertheless, it is more probable than in neutral media. Nevertheless, poly(safranin) is an efficient electrode modifier for sucralose electrochemical determination.
Theoretical description of sotolone electrochemical determination in wine in basic media over an undoped conducting polymer
(2023) Tkach, Volodymyr; Kushnir, Marta; Kopiika, Vira; Luganska, Olga; Omelyanchyk, Lyudmyla; Kormosh, Zholt; Kucher, Mykhailo; Garcia, Jarem; Palamarek, Karina; Bagrii, Konon; Medvedeva, Anzhelika; Oliveira, Sílvio C.; Yagodynets, Petro; Niyazov, Laziz; Musayeva, Dilfuza; Samadov, Bakhodirjon; Payentko, Viktoriia; Demianenko, Eugeny; Paiva Martins, Jose Inacio Ferrao; Vaz dos Reis, Lucinda; Karputina, Margarita; Khargeliia (Karputina), Daria; Nazymok, Yevgeniya; Ivanushko, Yana; Palytsia, Yulia
The electrochemical determination of sotolone in basic media over an undoped conducting polymer has been described for the first time. The alkaline hydrolysis, breaking the furanonic ring, leads to the appearance of an acid ion, entering the polymer matrix as a dopant. The stability analysis of the system, made by the development and investigation of the correspondent mathematical model, shows that the sotolon electrochemical determination is made efficiently. As for the oscillatory behavior, it may also be caused by the cyclic effect of chemical and electrochemical stages on the double electric layer capacitance and impedance.