This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Wykaz stosowanych skrótów Wprowadzenie 1. Kwas α-liponowy-właściwości fizykochemiczne 2. Kwas α-l... more Wykaz stosowanych skrótów Wprowadzenie 1. Kwas α-liponowy-właściwości fizykochemiczne 2. Kwas α-liponowy-właściwości biochemiczne 3. Metody oznaczania 3.1. Wysokosprawna chromatografia cieczowa (HPLC) 3.2. Chromatografia cienkowarstwowa (TLC) 3.3. Chromatografia gazowa (GC) 3.4. Spektrofotometria 3.5. Elektroforeza kapilarna (CE) 3.6. Metody elektrochemiczne 3.7. Oznaczanie LA związanego w lipolizynę Uwagi końcowe Piśmiennictwo cytowane A. SKORUPA, S. MICHAŁKIEWICZ 818 Dr Agata Skorupa w 2006 r. ukończyła studia chemiczne na Wydziale Matematyczno-Przyrodniczym Akademii Świętokrzyskiej (obecnie Uniwersytet Jana Kochanowskiego w Kielcach). Stopień doktora nauk chemicznych uzyskała w marcu 2016 r. na tym samym Wydziale. Pracuje na stanowisku asystenta w Zakładzie Chemii Analitycznej Instytutu Chemii UJK. Jej zainteresowania naukowe koncentrują się wokół właściwości elektrochemicznych substancji o znaczeniu biologicznym. Dr hab. Sławomir Michałkiewicz prof. UJK ukończył w 1989 r. studia chemiczne na Wydziale Matematyczno-Przyrodniczym Wyższej Szkoły Pedagogicznej w Kielcach (obecnie Uniwersytet Jana Kochanowskiego). Stopień doktora nauk chemicznych uzyskał w 1998 r. na Wydziale Chemii UMCS w Lublinie, a doktora habilitowanego (dziedzina nauk chemicznych, dyscyplina chemia) na Akademii Górniczo-Hutniczej w Krakowie w 2013 r. Pracuje na stanowisku profesora nadzwyczajnego w Zakładzie Chemii Analitycznej Instytutu Chemii UJK w Kielcach. Tematyka badawcza obejmuje właściwości elektrochemiczne i woltamperometryczne oznaczanie substancji biochemicznie czynnych.
Jpc – Journal Of Planar Chromatography – Modern Tlc, Aug 1, 2011
The use of thin-layer chromatography (TLC) for separation, identification and quantification of d... more The use of thin-layer chromatography (TLC) for separation, identification and quantification of different organic and inorganic substances is limited by the visualization of the separated and determined substances. In literature, there are innumerable references which present chemical, physical and biological methods of visualization of different kinds of organic and inorganic substances, especially the ones which do not absorb visible light. However, scientists are looking for new, more efficient reagents for a selective visualization of the definite part of a substance or, in some cases, for a specific determination of specific substances. This article describes a different method of visualization of the substances separated on the TLC plates. Special attention was paid to the different chemical reaction applied to obtain colour substrates of the reaction between separated substances and the property of the chosen derivate reagents. Describing different methods of visualization we tried to compare different groups of the determined substance, using different methods of their visualization. The analysis shows, for the first time, that different types of substances need different types of reactions and different types of reagents. The results of the TLC detection of the broad spectrum of the representative classes of organic derivatives are presented in table. The data illustrate the possibilities of TLC differentiation of the organic compounds which contain different active groups. The most unusual effect was obtained during the TLC application of the induced detection reagent. As a matter of fact, some sulphur atoms in their molecules are able to induce the iodine-azide reaction.
The electrochemical oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) on a carbon fiber microel... more The electrochemical oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) on a carbon fiber microelectrode (CF) and a glassy carbon macroelectrode (GC) in glacial acetic acid solutions was investigated using voltammetric techniques. Voltammograms recorded at these electrodes show well-defined single waves or peaks. The proposed mechanism of the anodic oxidation of DOPAC consists of two successive one-electron one-proton steps. The loss of the first electron proceeds irreversibly and determines the overall rate of the electrode process. This stage is accompanied by the generation of an unstable phenoxyl radical in position 4 of the aromatic ring. The second stage of the electrode reaction produces substituted orto-quinone as the final product of the electrode process of DOPAC. DOPAC exhibits more antioxidative power than synthetic BHT and can be useful in food protection against reactive oxygen species. The results presented can help to explain biochemical and antioxidative properties of DOPAC in a living cell and can be useful in determination of this compound in real samples.
rok 16, nr 6 substancje mające ten sam wspolczynnik opoźnienia Rf (wielkośc charakterystyczna dla... more rok 16, nr 6 substancje mające ten sam wspolczynnik opoźnienia Rf (wielkośc charakterystyczna dla danej substancji) są identyczne. Jest to jednak nie do konca poprawne stwierdzenie. Uproszczenie to stosuje sie wtedy, gdy mamy do czynienia z substancjami wzorcowymi. W takiej sytuacji wspolczynnik opoźnienia sugeruje nam identyfikowany związek, lecz nie daje 100% pewności identyczności obu substancji. Wykonując analize chromatograficzną w roznych ukladach (zmieniając faze ruchomą i nieruchomą) zwieksza sie prawdopodobienstwo identyfikacji. Substancje mozna uznac za identyczne jeśli wartości ich wspolczynnikow opoźnienia Rf w roznych warunkach są takie same. Na tej zasadzie przeprowadza sie analize jakościową chromatogramu. [1,2]. Inną mozliwością identyfikacji substancji moze byc wykorzystanie ich charakterystycznej barwy. Jeśli badana substancja po naniesieniu na warstwe chromatograficzną tworzy barwne plamki proces identyfikacji nie stwarza wiekszego problemu, sama charakterystyczna...
witaminy E w organizmach są błony komórkowe i lipoproteiny osocza krwi [3]. Witamina E zmniejsza ... more witaminy E w organizmach są błony komórkowe i lipoproteiny osocza krwi [3]. Witamina E zmniejsza wrażliwość skóry na promieniowanie UV, neutralizuje wolne rodniki i hamuje procesy starzenia się komórek. Ponadto reguluje gospodarkę wodną naskórka, reguluje pracę gruczołów łojowych oraz wspomaga mikrocyrkulację w naczyniach włosowatych. Tokoferole występują w bardzo wielu produktach spożywczych: oliwie z oliwek, olejach, owocach, warzywach, orzechach, zbowy jest nienasycony i zawiera 3 wiązania podwójne). Rozróżnieniem poszczególnych form witaminy E jest położenie grup metylowych (–CH3) w pierścieniu. Największą aktywność biologiczną wykazuje α-tokoferol, TOH (rys. 1.), który jest najczęściej występującą formą witaminy E w przyrodzie [1,2,3]. Ze względu na budowę, cząsteczka tokoferolu jest hydrofobowa, czyli dobrze rozpuszczalna w tłuszczach. Środowisk iem działania i głównego występowania rzącymi je lipidami, białkami i kwasami nukleinowymi. Naturalnymi sprzymierzeńcami w walce z wo...
Corresponding author: Agata SKORUPA – M.Sc., e-mail: agata.skorupa@ujk.edu.pl Introduction The si... more Corresponding author: Agata SKORUPA – M.Sc., e-mail: agata.skorupa@ujk.edu.pl Introduction The simple and effective technique for separating mixtures of substances is thin layer chromatography (TLC), which is widely used in the pharmaceutical industry and in the laboratory of organic synthesis. The principle of separation is a different division of components of the analyzed mixture between the sorbent and the eluent which migrates under the action of capillary forces. The basis of separation is a difference in the rate of migration of the individual substances through layer of adsorbent [1]. In 2009 Bo Zhang and co-workers [2] have published an article on a new technique of chromatography, which associates the rules for a thin-layer chromatography with a column chromatography. This technique is called a capillary action liquid chromatography (caLC). In caLC sorbent was placed in a capillary, which inner diameter is approx. 283-564 μm, and mobile phase migrates by capillary action f...
Rapid, simple, and safe for the environment voltammetric method for direct determination of total... more Rapid, simple, and safe for the environment voltammetric method for direct determination of total content of esters of p-hydroxybenzoic acid (PHB), named as parabens, in pharmaceutical preparations has been developed. Performed determinations were based on differential pulse voltammetry (DPV) at a carbon fiber disk microelectrode (CF) in glacial acetic acid containing 20% acetonitrile (v/v) and 0.1 mol L -1 sodium acetate as a supporting electrolyte. Linear calibration plots for PHB, methylparaben and propylparaben were obtained over the corresponding concentration range of 0.75 47.05, 0.89 40.73 and 1.20 36.62 mg L -1 with limit of detection of 0.07, 0.08 and 0.10 mg L -1 , respectively. This developed procedure allows the determination of parabens without the need for their separation from the matrices, and thereby aids in achieving desired accuracy, precision, and reproducibility of the results. This method has been successfully applied to their determination in commercially avai...
Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to... more Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, good electrical conductivity, wide potential range, and the possibility of using it in both aqueous and nonaqueous media. The electrodes made of carbon, and especially of carbon modified with different materials, are currently most often used in the voltammetric analysis of various compounds, including preservatives. The objective of this paper is to present the characteristics and suitability of different carbon materials for the construction of working electrodes used in the voltammetric analysis. Various carbon materials were considered and briefly discussed. Their analytical application was presented on the example of the preservatives commonly used in food, cosmetic, and pharmaceutical prep...
Thymol and carvacrol—the components of herbal spices—are known for their broad biological activit... more Thymol and carvacrol—the components of herbal spices—are known for their broad biological activity as antimicrobials and antioxidants. For this reason, it is important to develop new methods for their determination in plant material. A simple, rapid, and sensitive method for determination of total content of these analytes in herbal spices using differential pulse voltammetry (DPV) has been developed. The basis of the research is the oxidation process of isopropylmethylphenols on a platinum microelectrode in glacial acetic acid containing acetonitrile (20%, v/v) and 0.1 mol L−1 sodium perchlorate as the supporting electrolyte. Linear voltammetric responses for thymol and carvacrol were obtained in a wide concentration range from 0.39–1105 and 0.47–640 µg mL−1, with a low detection limit of 0.04 and 0.05 µg mL−1, respectively. The analysis was performed using the multiple standard addition method. The results of the voltammetric determination are in good agreement with the data of th...
Rapid, simple, and safe for the environment voltammetric method for direct determination of total... more Rapid, simple, and safe for the environment voltammetric method for direct determination of total content of esters of p-hydroxybenzoic acid (PHB), named as parabens, in pharmaceutical preparations has been developed. Performed determinations were based on differential pulse voltammetry (DPV) at a carbon fiber disk microelectrode (CF) in glacial acetic acid containing 20% acetonitrile (v/v) and 0.1 mol L -1 sodium acetate as a supporting electrolyte. Linear calibration plots for PHB, methylparaben and propylparaben were obtained over the corresponding concentration range of 0.75 47.05, 0.89 40.73 and 1.20 36.62 mg L -1 with limit of detection of 0.07, 0.08 and 0.10 mg L -1 , respectively. This developed procedure allows the determination of parabens without the need for their separation from the matrices, and thereby aids in achieving desired accuracy, precision, and reproducibility of the results. This method has been successfully applied to their determination in commercially avai...
A simple, highly sensitive, and selective differential pulse voltammetry method for the determina... more A simple, highly sensitive, and selective differential pulse voltammetry method for the determination of α-lipoic acid (LA) in pharmaceutical preparations was developed and validated. The method is based on a quasi-reversible, diffusion-controlled, one-electron anodic oxidation of LA on a boron-doped diamond electrode (BDDE) in a McIlvaine (citrate-phosphate, C-PB) buffer solution at pH 3.0. For the first time, this environment was used for LA determination. A linear calibration curve was obtained within the concentration range 5.82 × 10−8 to 4.00 × 10−4 mol L−1 with a correlation coefficient of 0.9999. The limits of detection was estimated to be 1.94 × 10−8 mol L−1, which is one of the lowest values characteristic of voltammetric and chromatographic methods of LA determination. The proposed procedure is sensitive, accurate, and precise. Its utility was demonstrated in the determination of LA in pharmaceuticals without the need for its separation from the matrices. The results were ...
Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to... more Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, good electrical conductivity, wide potential range, and the possibility of using it in both aqueous and nonaqueous media. The electrodes made of carbon, and especially of carbon modified with different materials, are currently most often used in the voltammetric analysis of various compounds, including preservatives. The objective of this paper is to present the characteristics and suitability of different carbon materials for the construction of working electrodes used in the voltammetric analysis. Various carbon materials were considered and briefly discussed. Their analytical application was presented on the example of the preservatives commonly used in food, cosmetic, and pharmaceutical prep...
Thymol and carvacrol—the components of herbal spices—are known for their broad biological activit... more Thymol and carvacrol—the components of herbal spices—are known for their broad biological activity as antimicrobials and antioxidants. For this reason, it is important to develop new methods for their determination in plant material. A simple, rapid, and sensitive method for determination of total content of these analytes in herbal spices using differential pulse voltammetry (DPV) has been developed. The basis of the research is the oxidation process of isopropylmethylphenols on a platinum microelectrode in glacial acetic acid containing acetonitrile (20%, v/v) and 0.1 mol L−1 sodium perchlorate as the supporting electrolyte. Linear voltammetric responses for thymol and carvacrol were obtained in a wide concentration range from 0.39–1105 and 0.47–640 µg mL−1, with a low detection limit of 0.04 and 0.05 µg mL−1, respectively. The analysis was performed using the multiple standard addition method. The results of the voltammetric determination are in good agreement with the data of th...
A simple, highly sensitive, and selective differential pulse voltammetry method for the determina... more A simple, highly sensitive, and selective differential pulse voltammetry method for the determination of α-lipoic acid (LA) in pharmaceutical preparations was developed and validated. The method is based on a quasi-reversible, diffusion-controlled, one-electron anodic oxidation of LA on a boron-doped diamond electrode (BDDE) in a McIlvaine (citrate-phosphate, C-PB) buffer solution at pH 3.0. For the first time, this environment was used for LA determination. A linear calibration curve was obtained within the concentration range 5.82 × 10−8 to 4.00 × 10−4 mol L−1 with a correlation coefficient of 0.9999. The limits of detection was estimated to be 1.94 × 10−8 mol L−1, which is one of the lowest values characteristic of voltammetric and chromatographic methods of LA determination. The proposed procedure is sensitive, accurate, and precise. Its utility was demonstrated in the determination of LA in pharmaceuticals without the need for its separation from the matrices. The results were ...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Wykaz stosowanych skrótów Wprowadzenie 1. Kwas α-liponowy-właściwości fizykochemiczne 2. Kwas α-l... more Wykaz stosowanych skrótów Wprowadzenie 1. Kwas α-liponowy-właściwości fizykochemiczne 2. Kwas α-liponowy-właściwości biochemiczne 3. Metody oznaczania 3.1. Wysokosprawna chromatografia cieczowa (HPLC) 3.2. Chromatografia cienkowarstwowa (TLC) 3.3. Chromatografia gazowa (GC) 3.4. Spektrofotometria 3.5. Elektroforeza kapilarna (CE) 3.6. Metody elektrochemiczne 3.7. Oznaczanie LA związanego w lipolizynę Uwagi końcowe Piśmiennictwo cytowane A. SKORUPA, S. MICHAŁKIEWICZ 818 Dr Agata Skorupa w 2006 r. ukończyła studia chemiczne na Wydziale Matematyczno-Przyrodniczym Akademii Świętokrzyskiej (obecnie Uniwersytet Jana Kochanowskiego w Kielcach). Stopień doktora nauk chemicznych uzyskała w marcu 2016 r. na tym samym Wydziale. Pracuje na stanowisku asystenta w Zakładzie Chemii Analitycznej Instytutu Chemii UJK. Jej zainteresowania naukowe koncentrują się wokół właściwości elektrochemicznych substancji o znaczeniu biologicznym. Dr hab. Sławomir Michałkiewicz prof. UJK ukończył w 1989 r. studia chemiczne na Wydziale Matematyczno-Przyrodniczym Wyższej Szkoły Pedagogicznej w Kielcach (obecnie Uniwersytet Jana Kochanowskiego). Stopień doktora nauk chemicznych uzyskał w 1998 r. na Wydziale Chemii UMCS w Lublinie, a doktora habilitowanego (dziedzina nauk chemicznych, dyscyplina chemia) na Akademii Górniczo-Hutniczej w Krakowie w 2013 r. Pracuje na stanowisku profesora nadzwyczajnego w Zakładzie Chemii Analitycznej Instytutu Chemii UJK w Kielcach. Tematyka badawcza obejmuje właściwości elektrochemiczne i woltamperometryczne oznaczanie substancji biochemicznie czynnych.
Jpc – Journal Of Planar Chromatography – Modern Tlc, Aug 1, 2011
The use of thin-layer chromatography (TLC) for separation, identification and quantification of d... more The use of thin-layer chromatography (TLC) for separation, identification and quantification of different organic and inorganic substances is limited by the visualization of the separated and determined substances. In literature, there are innumerable references which present chemical, physical and biological methods of visualization of different kinds of organic and inorganic substances, especially the ones which do not absorb visible light. However, scientists are looking for new, more efficient reagents for a selective visualization of the definite part of a substance or, in some cases, for a specific determination of specific substances. This article describes a different method of visualization of the substances separated on the TLC plates. Special attention was paid to the different chemical reaction applied to obtain colour substrates of the reaction between separated substances and the property of the chosen derivate reagents. Describing different methods of visualization we tried to compare different groups of the determined substance, using different methods of their visualization. The analysis shows, for the first time, that different types of substances need different types of reactions and different types of reagents. The results of the TLC detection of the broad spectrum of the representative classes of organic derivatives are presented in table. The data illustrate the possibilities of TLC differentiation of the organic compounds which contain different active groups. The most unusual effect was obtained during the TLC application of the induced detection reagent. As a matter of fact, some sulphur atoms in their molecules are able to induce the iodine-azide reaction.
The electrochemical oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) on a carbon fiber microel... more The electrochemical oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) on a carbon fiber microelectrode (CF) and a glassy carbon macroelectrode (GC) in glacial acetic acid solutions was investigated using voltammetric techniques. Voltammograms recorded at these electrodes show well-defined single waves or peaks. The proposed mechanism of the anodic oxidation of DOPAC consists of two successive one-electron one-proton steps. The loss of the first electron proceeds irreversibly and determines the overall rate of the electrode process. This stage is accompanied by the generation of an unstable phenoxyl radical in position 4 of the aromatic ring. The second stage of the electrode reaction produces substituted orto-quinone as the final product of the electrode process of DOPAC. DOPAC exhibits more antioxidative power than synthetic BHT and can be useful in food protection against reactive oxygen species. The results presented can help to explain biochemical and antioxidative properties of DOPAC in a living cell and can be useful in determination of this compound in real samples.
rok 16, nr 6 substancje mające ten sam wspolczynnik opoźnienia Rf (wielkośc charakterystyczna dla... more rok 16, nr 6 substancje mające ten sam wspolczynnik opoźnienia Rf (wielkośc charakterystyczna dla danej substancji) są identyczne. Jest to jednak nie do konca poprawne stwierdzenie. Uproszczenie to stosuje sie wtedy, gdy mamy do czynienia z substancjami wzorcowymi. W takiej sytuacji wspolczynnik opoźnienia sugeruje nam identyfikowany związek, lecz nie daje 100% pewności identyczności obu substancji. Wykonując analize chromatograficzną w roznych ukladach (zmieniając faze ruchomą i nieruchomą) zwieksza sie prawdopodobienstwo identyfikacji. Substancje mozna uznac za identyczne jeśli wartości ich wspolczynnikow opoźnienia Rf w roznych warunkach są takie same. Na tej zasadzie przeprowadza sie analize jakościową chromatogramu. [1,2]. Inną mozliwością identyfikacji substancji moze byc wykorzystanie ich charakterystycznej barwy. Jeśli badana substancja po naniesieniu na warstwe chromatograficzną tworzy barwne plamki proces identyfikacji nie stwarza wiekszego problemu, sama charakterystyczna...
witaminy E w organizmach są błony komórkowe i lipoproteiny osocza krwi [3]. Witamina E zmniejsza ... more witaminy E w organizmach są błony komórkowe i lipoproteiny osocza krwi [3]. Witamina E zmniejsza wrażliwość skóry na promieniowanie UV, neutralizuje wolne rodniki i hamuje procesy starzenia się komórek. Ponadto reguluje gospodarkę wodną naskórka, reguluje pracę gruczołów łojowych oraz wspomaga mikrocyrkulację w naczyniach włosowatych. Tokoferole występują w bardzo wielu produktach spożywczych: oliwie z oliwek, olejach, owocach, warzywach, orzechach, zbowy jest nienasycony i zawiera 3 wiązania podwójne). Rozróżnieniem poszczególnych form witaminy E jest położenie grup metylowych (–CH3) w pierścieniu. Największą aktywność biologiczną wykazuje α-tokoferol, TOH (rys. 1.), który jest najczęściej występującą formą witaminy E w przyrodzie [1,2,3]. Ze względu na budowę, cząsteczka tokoferolu jest hydrofobowa, czyli dobrze rozpuszczalna w tłuszczach. Środowisk iem działania i głównego występowania rzącymi je lipidami, białkami i kwasami nukleinowymi. Naturalnymi sprzymierzeńcami w walce z wo...
Corresponding author: Agata SKORUPA – M.Sc., e-mail: agata.skorupa@ujk.edu.pl Introduction The si... more Corresponding author: Agata SKORUPA – M.Sc., e-mail: agata.skorupa@ujk.edu.pl Introduction The simple and effective technique for separating mixtures of substances is thin layer chromatography (TLC), which is widely used in the pharmaceutical industry and in the laboratory of organic synthesis. The principle of separation is a different division of components of the analyzed mixture between the sorbent and the eluent which migrates under the action of capillary forces. The basis of separation is a difference in the rate of migration of the individual substances through layer of adsorbent [1]. In 2009 Bo Zhang and co-workers [2] have published an article on a new technique of chromatography, which associates the rules for a thin-layer chromatography with a column chromatography. This technique is called a capillary action liquid chromatography (caLC). In caLC sorbent was placed in a capillary, which inner diameter is approx. 283-564 μm, and mobile phase migrates by capillary action f...
Rapid, simple, and safe for the environment voltammetric method for direct determination of total... more Rapid, simple, and safe for the environment voltammetric method for direct determination of total content of esters of p-hydroxybenzoic acid (PHB), named as parabens, in pharmaceutical preparations has been developed. Performed determinations were based on differential pulse voltammetry (DPV) at a carbon fiber disk microelectrode (CF) in glacial acetic acid containing 20% acetonitrile (v/v) and 0.1 mol L -1 sodium acetate as a supporting electrolyte. Linear calibration plots for PHB, methylparaben and propylparaben were obtained over the corresponding concentration range of 0.75 47.05, 0.89 40.73 and 1.20 36.62 mg L -1 with limit of detection of 0.07, 0.08 and 0.10 mg L -1 , respectively. This developed procedure allows the determination of parabens without the need for their separation from the matrices, and thereby aids in achieving desired accuracy, precision, and reproducibility of the results. This method has been successfully applied to their determination in commercially avai...
Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to... more Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, good electrical conductivity, wide potential range, and the possibility of using it in both aqueous and nonaqueous media. The electrodes made of carbon, and especially of carbon modified with different materials, are currently most often used in the voltammetric analysis of various compounds, including preservatives. The objective of this paper is to present the characteristics and suitability of different carbon materials for the construction of working electrodes used in the voltammetric analysis. Various carbon materials were considered and briefly discussed. Their analytical application was presented on the example of the preservatives commonly used in food, cosmetic, and pharmaceutical prep...
Thymol and carvacrol—the components of herbal spices—are known for their broad biological activit... more Thymol and carvacrol—the components of herbal spices—are known for their broad biological activity as antimicrobials and antioxidants. For this reason, it is important to develop new methods for their determination in plant material. A simple, rapid, and sensitive method for determination of total content of these analytes in herbal spices using differential pulse voltammetry (DPV) has been developed. The basis of the research is the oxidation process of isopropylmethylphenols on a platinum microelectrode in glacial acetic acid containing acetonitrile (20%, v/v) and 0.1 mol L−1 sodium perchlorate as the supporting electrolyte. Linear voltammetric responses for thymol and carvacrol were obtained in a wide concentration range from 0.39–1105 and 0.47–640 µg mL−1, with a low detection limit of 0.04 and 0.05 µg mL−1, respectively. The analysis was performed using the multiple standard addition method. The results of the voltammetric determination are in good agreement with the data of th...
Rapid, simple, and safe for the environment voltammetric method for direct determination of total... more Rapid, simple, and safe for the environment voltammetric method for direct determination of total content of esters of p-hydroxybenzoic acid (PHB), named as parabens, in pharmaceutical preparations has been developed. Performed determinations were based on differential pulse voltammetry (DPV) at a carbon fiber disk microelectrode (CF) in glacial acetic acid containing 20% acetonitrile (v/v) and 0.1 mol L -1 sodium acetate as a supporting electrolyte. Linear calibration plots for PHB, methylparaben and propylparaben were obtained over the corresponding concentration range of 0.75 47.05, 0.89 40.73 and 1.20 36.62 mg L -1 with limit of detection of 0.07, 0.08 and 0.10 mg L -1 , respectively. This developed procedure allows the determination of parabens without the need for their separation from the matrices, and thereby aids in achieving desired accuracy, precision, and reproducibility of the results. This method has been successfully applied to their determination in commercially avai...
A simple, highly sensitive, and selective differential pulse voltammetry method for the determina... more A simple, highly sensitive, and selective differential pulse voltammetry method for the determination of α-lipoic acid (LA) in pharmaceutical preparations was developed and validated. The method is based on a quasi-reversible, diffusion-controlled, one-electron anodic oxidation of LA on a boron-doped diamond electrode (BDDE) in a McIlvaine (citrate-phosphate, C-PB) buffer solution at pH 3.0. For the first time, this environment was used for LA determination. A linear calibration curve was obtained within the concentration range 5.82 × 10−8 to 4.00 × 10−4 mol L−1 with a correlation coefficient of 0.9999. The limits of detection was estimated to be 1.94 × 10−8 mol L−1, which is one of the lowest values characteristic of voltammetric and chromatographic methods of LA determination. The proposed procedure is sensitive, accurate, and precise. Its utility was demonstrated in the determination of LA in pharmaceuticals without the need for its separation from the matrices. The results were ...
Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to... more Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, good electrical conductivity, wide potential range, and the possibility of using it in both aqueous and nonaqueous media. The electrodes made of carbon, and especially of carbon modified with different materials, are currently most often used in the voltammetric analysis of various compounds, including preservatives. The objective of this paper is to present the characteristics and suitability of different carbon materials for the construction of working electrodes used in the voltammetric analysis. Various carbon materials were considered and briefly discussed. Their analytical application was presented on the example of the preservatives commonly used in food, cosmetic, and pharmaceutical prep...
Thymol and carvacrol—the components of herbal spices—are known for their broad biological activit... more Thymol and carvacrol—the components of herbal spices—are known for their broad biological activity as antimicrobials and antioxidants. For this reason, it is important to develop new methods for their determination in plant material. A simple, rapid, and sensitive method for determination of total content of these analytes in herbal spices using differential pulse voltammetry (DPV) has been developed. The basis of the research is the oxidation process of isopropylmethylphenols on a platinum microelectrode in glacial acetic acid containing acetonitrile (20%, v/v) and 0.1 mol L−1 sodium perchlorate as the supporting electrolyte. Linear voltammetric responses for thymol and carvacrol were obtained in a wide concentration range from 0.39–1105 and 0.47–640 µg mL−1, with a low detection limit of 0.04 and 0.05 µg mL−1, respectively. The analysis was performed using the multiple standard addition method. The results of the voltammetric determination are in good agreement with the data of th...
A simple, highly sensitive, and selective differential pulse voltammetry method for the determina... more A simple, highly sensitive, and selective differential pulse voltammetry method for the determination of α-lipoic acid (LA) in pharmaceutical preparations was developed and validated. The method is based on a quasi-reversible, diffusion-controlled, one-electron anodic oxidation of LA on a boron-doped diamond electrode (BDDE) in a McIlvaine (citrate-phosphate, C-PB) buffer solution at pH 3.0. For the first time, this environment was used for LA determination. A linear calibration curve was obtained within the concentration range 5.82 × 10−8 to 4.00 × 10−4 mol L−1 with a correlation coefficient of 0.9999. The limits of detection was estimated to be 1.94 × 10−8 mol L−1, which is one of the lowest values characteristic of voltammetric and chromatographic methods of LA determination. The proposed procedure is sensitive, accurate, and precise. Its utility was demonstrated in the determination of LA in pharmaceuticals without the need for its separation from the matrices. The results were ...
Uploads
Papers by Agata Skorupa