26 (2020) Scientific papers, Series A
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/76706
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Článekpeer-reviewedpublished Otevřený přístup 50 years of high performance liquid chromatography: The contribution of the Department of Analytical Chemistry in Pardubice(University of Pardubice, 2020) Jandera, PavelThis article surveys the research activities and contributions of the Department of Analytical Chemistry (first at the Institute of Chemical Technology, later at the Faculty of Chemical Technology of the University of Pardubice), to the field of High Performance Liquid Chromatography in the half a century period between 1969 and 2018. The research topics investigated include various theoretical and practical analytical or preparative techniques, in agreement with the general development trends in the field. The attention is focused on the mechanism and predictive modelling of the retention and separation selectivity in the reversed-phase, organic and aqueous normal phase, ion-pairing, salting-out, micellar and mixed-mode liquid chromatography modes. The effects of the stationary phase, of the mobile phases, and of the sample structure on the retention were investigated in detail. The principal point of the research was the development and verification of the new theory of gradient elution. An important part of the recent research activities has been oriented on the theory and practical applications of the new two-dimensional liquid chromatography technique. During the past half a century, new applications of liquid chromatography were developed in the environmental analysis, in the analysis of drugs and their metabolite products, industrial dyes, intermediates, surfactants, of the phenolic antioxidants and plant oils in food and beverages; some attention being also paid to the separation of chiral compounds.Článekpeer-reviewedpublished Otevřený přístup Electrochemical behaviour of substances responsible for the vanilla aroma and a study of their structural analogues at the glassy carbon electrode(University of Pardubice, 2020) Farag, Amir Shaaban; Švancara, Ivan; Sýs, MilanIn this article, the electrochemical behaviour of vanillin, ethylvanilin, and of their structural analogues has been studied at the glassy carbon electrode using cyclic voltammetry. Based on experimental observations and information from literature, the respective electrode reaction pathways were proposed according to the ECE mechanisms in all cases, when up to three oxidation products were identified from one reactant. It has been found that the electrode oxidation of vanillin and ethylvanillin occurs in one single step, followed by hydrolysis in ortho-position and/or cleavage of the corresponding alcohol, giving rise to two electrochemically reversible oxidation products.Článekpeer-reviewedpublished Otevřený přístup Comparison of two different approaches for determination of biomimetic activity of selected copper complexes(University of Pardubice, 2020) Sýs, Milan; Novák, Miroslav; Mikysek, TomášIn this article, an evaluation of the catecholase activity of the recently synthesized copper complexes towards dopamine is reported based on a comparison of the performance of two different techniques – UV-Vis spectrophotometry and hydrodynamic amperometry. The results obtained were confronted with those published for natural tyrosinase enzyme (isolated from mushroom 'Agaricus bisporus') and defined by Michaelis–Menten kinetics model. Besides a finding of comparable catalytic activity for the copper catalysts tested, it has to be emphasised that all the measurements have been performed in methanol, in which tyrosinase enzyme loses its catalytic activity.Článekpeer-reviewedpublished Otevřený přístup Multi-element analysis of urine using octopole collision cell ICP-Q-MS(University of Pardubice, 2020) Patočka, Jan; Husáková, LenkaThis study presents an octopole collision cell ICP-Q-MS methodology for interferencefree multi-element analysis of urine. The attention was paid to the performance of the 4th generation octopole-based collision cell in the Agilent 7900 Series ICP-MS in He-mode with kinetic energy discrimination (KED) for the elimination of polyatomic ions that are the main source of spectral interferences during the analysis of numerous elements, such as V, Cr, Fe, Co, Ni, Cu, As, Se, etc. However, collision mode using helium gas had the additional benefit of reducing the response for major matrix elements, thereby effectively raising the upper linear calibration range for these elements. Afterwards, the major elements could be determined in the same analytical run as the trace elements in the range of analytes typically reported in urine samples. The analysis was carried out after the initial 10-fold dilution of the urine samples and Rh was used as an internal standard to diminish non-spectral interferences originating from the sample matrix. Due to the excellent detection capability and practically no interferences, the method could be finally employed for analysis of 26 elements. Accuracy of the method was checked by the regular use of certified reference materials SeronormTM Trace Elements Urine Blank Lot OK4636 and SeronormTM Trace Elements Urine L-1 Lot 1011644, as well as by accurate isotope ratios measurements if possible.Článekpeer-reviewedpublished Otevřený přístup Effect of long-term storage on degradation of 21 phenolic compounds in green tea(University of Pardubice, 2020) Kalendová, Petra; Meloun, Milan; Česlová, LenkaThe storage resistance of 21 selected phenolic compounds present in ten samples of commercially available green tea was monitored using the HPLC/MS/MS over a 16 weeks period using multivariate statistical analysis to compare the different types of packaging. The HPLC/MS/MS method with the computer-aided analysis enabled the fast evaluation of the long-time storage resistance of valuable compounds present in green tea, yielding useful information to customers about their degradation, which affected the sensory properties of the green tea, such as taste and colour. An explanatory data analysis provided an initial visualization of the multivariate data matrix while a factor analysis, hierarchical cluster analysis and discriminant analysis enabled the classification of the green tea samples into clusters according to the storage resistance of the compounds of interest. A significant reduction in the content of all monitored compounds was indicated after 3 weeks of storage, which was also found to be dependent on the type of packaging used. The samples in a plastic box were more stable during long-time storage in comparison to the samples in a paper box.Článekpeer-reviewedpublished Otevřený přístup Determination of oleocanthal in extra virgin olive oils using high-performance liquid chromatography(University of Pardubice, 2020) Klikarová, Jitka; Jakubů, Klára; Česlová, Lenka; Fischer, JanThis work is focused on the determination of oleocanthal in nineteen extra virgin olive oils plus one sample of the olive pomace oil using reversed-phase high-performance liquid chromatography (RP-HPLC) coupled either with a spectrophotometric detector (set at λ = 275 nm) or a mass spectrometer. Sample pre-treatment including a two-step liquidliquid extraction by polar solvents was performed and thoroughly optimised. The extract of oleocanthal was analysed using Poroshell 120 EC-C18 column (150 × 3 mm, i.d. 2.7 μm) in combination with the binary mobile phases consisting of water and acetonitrile. The sum of oleocanthal hemiacetals was quantified by the calibration curve method and the standard addition method. The content of oleocanthal in the samples was found within a range of 2.8–27.2 mg/100 g. It is shown that the method can also be used for evaluation of the olive oil quality.Článekpeer-reviewedpublished Otevřený přístup Determination of selected pesticides in honey and mead by HPLC(University of Pardubice, 2020) Pravcová, Kateřina; Macháčková, Nikola; Česlová, LenkaThe aim of this study was to monitor selected pesticides (Carbendazim, Acetamiprid, Thiacloprid, Epoxiconazole, Metconazole, Prochloraz, Deltamethrin, and T-fluvalinate) in honey and mead samples by reversed-phase liquid chromatography with spectrophotometric detection after QuEChERS extraction. The final separation was performed on YMC triart C18 column with mobile phase consisting of water and acetonitrile. The identification of selected pesticides in samples of honey and mead was performed on the basis of retention times conformity with the standards and quantification using the calibration curve method.Článekpeer-reviewedpublished Otevřený přístup Comparison of HPLC and electrochemical determination of 5-hydroxymethylfurfural in honey and mead samples(University of Pardubice, 2020) Pravcová, Kateřina; Mikysek, Tomáš; Česlová, LenkaThe content of 5-hydroxymethylfurfural (HMF) in honey and mead is strongly influenced by the technological process of these products and could be used as the parameter of choice to assess the quality of honey and mead. Therefore, the aim of this work was the comparison of well established reversed-phase high performance liquid chromatography (RP-HPLC) with voltammetric determination at the glassy carbon electrode. The final HPLC separation was performed on an Ascentis Express C18 column (150 × 3 mm, 2.7 μm) using isocratic elution with 10 % methanol in water. In total, 9 samples (6 honeys and 3 meads) were used for determination of the content of HMF.Článekpeer-reviewedpublished Otevřený přístup Classification of the alcoholic beverages by using electronic nose technique based on ultra-fast GC(University of Pardubice, 2020) Surmová, Silvie; Wiśniewska, Paulina; Śliwińska, Magdalena; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Ventura, Karel; Adam, Martin; Eisner, AlešEach alcoholic beverage has its own distinct aroma and unique flavor. An Electronic nose (E-nose) is an instrumental tool which allows one to analyze the aroma of samples. This work illustrates the use of E-nose for the determination of characteristic aromas of seven different alcoholic beverages (bourbon, brandy, cognac, vodka, liqueurs made from pears, and fruit spirits made from lemon). The following chemometrics methods for the data analysis were employed for the classification of alcoholic beverages: principal component analysis (PCA), discriminant factorial analysis (DFA, and soft independent modelling of class analogies (SIMCA). The results show that chemometrics methods PCA and DFA allow us the determination of the individual alcoholic groups of fruit spirits, bourbon, cognac, and brandy but there is a difficulty with separation of liqueur, gin, and vodka points from one group. Only the SIMCA method allowed to distinguish the point belonging to all groups without any approximation of graph fragments.Článekpeer-reviewedpublished Otevřený přístup Determination and profiling of fatty acids in dried breast milk spot(University of Pardubice, 2020) Kopčil, Michal; Janeček, Radim; Fukasová, Petra; Kanďár, RomanA method was developed for the determination of fatty acids in dried breast milk spot and plasma using gas chromatography with mass spectrometry and flame ionization detection. The breast milk was sampled onto a collection paper treated with butylated hydroxytoluene. Fatty acids were derivatized with acetyl chloride in methanol to form fatty acids methyl esters. Our results indicate that the concentrations of fatty acids found in human milk can be used for assessing the intake and needs of infants.