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Horvath K.,University of Pannonia | Felinger A.,MTA PTE Molecular Interactions in Separation Science Research Group | Felinger A.,University of Pecs
Journal of Chromatography A | Year: 2015

The applicability of core-shell phases in preparative separations was studied by a modeling approach. The preparative separations were optimized for two compounds having bi-Langmuir isotherms. The differential mass balance equation of chromatography was solved by the Rouchon algorithm. The results show that as the size of the core increases, larger particles can be used in separations, resulting in higher applicable flow rates, shorter cycle times. Due to the decreasing volume of porous layer, the loadability of the column dropped significantly. As a result, the productivity and economy of the separation decreases. It is shown that if it is possible to optimize the size of stationary phase particles for the given separation task, the use of core-shell phases are not beneficial. The use of core-shell phases proved to be advantageous when the goal is to build preparative column for general purposes (e.g. for purification of different products) in small scale separations. © 2015 Elsevier B.V. Source


Simon J.,University of Pecs | Felinger A.,University of Pecs | Felinger A.,MTA PTE Molecular Interactions in Separation Science Research Group
Journal of Chromatography A | Year: 2015

Two-dimensional (2D) correlation analysis is a well-established tool in spectroscopy. Despite its versatility in various measurement systems, 2D correlation has not yet become popular in separation science. 2D correlation is seldom used in chromatography; only a few a studies can be found on this topic and most of those publications report about gel chromatography. In the present study, 2D correlation analysis is applied to chromatograms. In this study, a simple method is built for studying the similarities and dissimilarities between a number of chromatograms. We present the applicability of the method by two examples, where the repeatability and reproducibility of the analytical and nonlinear measurements in HPLC are evaluated and demonstrated. In order to validate the results of 2D correlation analysis, they are compared to principal component analysis (PCA). We confirm the equivalence in the interpretation of the results obtained with the two methods of calculation. The results confirm that 2D correlation can be a successful chemometric tool in chromatography. © 2015 Elsevier B.V. Source


Horvath K.,University of Pannonia | Sepsey A.,MTA PTE Molecular Interactions in Separation Science Research Group | Hajos P.,University of Pannonia
Journal of Chromatography A | Year: 2015

An algorithm was developed for the minimization of consumption of organic solvent in comprehensive two-dimensional liquid chromatography (2DLC). It was shown that one can reach higher peak capacities only by using more eluent. The equilibration volume of the second dimension, however, did not affect the solvent consumption significantly. Calculations confirmed that the same target peak capacity could be achieved by consuming significantly different volume of organic modifier depending on the number of fractions analyzed in the second dimension suggesting that 2D separations can be optimized for eluent consumption. It was shown that minimization of eluent usage requires the use of small and high efficient columns in the second dimension. A simple equation was derived for the calculation of the optimal number of collected fractions from the first dimension that allowed the minimization of eluent usage, cost and environmental impact of comprehensive 2DLC separations. © 2014 Elsevier B.V. Source


Bacskay I.,University of Pecs | Sepsey A.,MTA PTE Molecular Interactions in Separation Science Research Group | Felinger A.,University of Pecs | Felinger A.,MTA PTE Molecular Interactions in Separation Science Research Group
Journal of Chromatography A | Year: 2014

The mesopore structure (pore size and its distribution) for the first and second generations of silica-based monolithic columns was determined by inverse size-exclusion chromatography. The effect of pore size distribution was considered via the molecular theory of size-exclusion chromatography. The molecular theory of chromatography allows taking into account the kinetics of the pore ingress and egress processes, the heterogeneity of the pore sizes and polymer polydispersity. Besides, the mesopore structure, the characteristic domain sizes of the macropores present in the first and second generations of silica-based monolithic columns were also characterized. © 2014 Elsevier B.V. Source


Sepsey A.,MTA PTE Molecular Interactions in Separation Science Research Group | Bacskay I.,University of Pecs | Felinger A.,MTA PTE Molecular Interactions in Separation Science Research Group | Felinger A.,University of Pecs
Journal of Chromatography A | Year: 2014

Chromatographic processes can conveniently be modeled at a microscopic level using the molecular theory of chromatography. This molecular or microscopic theory is completely general; therefore it can be used for any chromatographic process such as adsorption, partition, ion-exchange or size exclusion chromatography. The molecular theory of chromatography allows taking into account the kinetics of the pore ingress and egress processes, the heterogeneity of the pore sizes and polymer polydispersion. In this work, we assume that the pore size in the stationary phase of chromatographic columns is governed by a wide lognormal distribution. This property is integrated into the molecular model of size exclusion chromatography and the moments of the elution profiles were calculated for several kinds of pore structure. Our results demonstrate that wide pore size distributions have strong influence on the retention properties (retention time, peak width, and peak shape) of macromolecules. The novel model allows us to estimate the real pore size distribution of commonly used HPLC stationary phases, and the effect of this distribution on the size exclusion process. © 2014 Elsevier B.V. Source

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