TY - JOUR AU - Kazmouz, Muhamad Yahia AU - Felinger, Attila TI - The Impact of Water as an Additive on the Elution of Some Basic Organic Compounds in Supercritical Fluid Chromatography JF - MOLECULES J2 - MOLECULES VL - 29 PY - 2024 IS - 9 PG - 15 SN - 1420-3049 DO - 10.3390/molecules29092124 UR - https://m2.mtmt.hu/api/publication/34835501 ID - 34835501 AB - In this study, water was used as an additive in the methanol-modified carbon dioxide-based eluent for the elution of some basic organic compounds from a hybrid silica column via supercritical fluid chromatography (SFC). The experiments were applied to sulfonamides, propranolol, and other organic nitrogen compounds involving aromatic rings from different classes of amine, pyrimidine, and purine with different pKa values (the pKa values for the studied analytes range from 4.6 to 10.4). The results revealed different responses to the different percentages of water addition. Adding 1~2% of water to the modifier (methanol) led to a positive effect manifested by more symmetrical peak shapes and reduced retention times for most compounds. The key factor for this improvement in the properties of chromatographic peaks is due to the adsorption of water on the silanol groups of the stationary phase, consequently resembling the phenomena observed in hydrophilic interaction liquid chromatography (HILIC). Moreover, the availability of hydrogen bond acceptor and donor sites in the analyte structure is an important factor to be considered when adding water as an additive to the modifier for improving the chromatographic peaks. However, introducing water in an amount higher than 3% resulted in perturbed chromatographic signals. It was also found that water as an additive alone could not successfully elute propranolol from the hybrid silica column with an acceptable peak shape; thus, the addition of a strong base such as amine salts was also necessary. The proposed use of a particular amount of water in the mobile phase could have a positive effect compared to the same mobile phase without water, improving the chromatographic peak properties of the elution of some basic organic compounds from the hybrid silica column. LA - English DB - MTMT ER - TY - JOUR AU - Rédei, Csanád AU - Buratti, Alessandro AU - Catani, Martina AU - Felinger, Attila TI - Exploring the application limits of different hold-up time markers in supercritical fluid chromatography JF - ANALYTICAL AND BIOANALYTICAL CHEMISTRY J2 - ANAL BIOANAL CHEM VL - 416 PY - 2024 IS - 6 SP - 1485 EP - 1492 PG - 8 SN - 1618-2642 DO - 10.1007/s00216-024-05152-9 UR - https://m2.mtmt.hu/api/publication/34541558 ID - 34541558 AB - The study focuses on the application range of nitrous oxide as a hold-up time marker in supercritical fluid chromatography (SFC). This compound has been suggested a decade ago to be used as unretained marker, something that the field of SFC was missing for a long time, since its beneficial properties make it an ideal candidate as hold-up time marker. Determination of the hold-up volume and actual volumetric flow rates have always been problematic in SFC due to the compressibility of carbon dioxide and one part of this is the difficulty of hold-up time measurements. Depending on the mobile phase, different methods have been used to measure the hold-up time with varying results. Nitrous oxide and other molecules have been compared in different conditions, mobile phases and stationary phases. In all cases, nitrous oxide gave the lowest elution times. However, detection was difficult in mobile phases containing 10% or more of organic modifier, because most solvents mask the signal of nitrous oxide. Interestingly, the choice of stationary phase also had a slight effect on detection, while different pressure and temperature settings affected each compound in a different manner. LA - English DB - MTMT ER - TY - JOUR AU - Dembek, Mikołaj AU - Bacskay, Ivett Orsolya AU - Buratti, Alessandro AU - Catani, Martina AU - Felinger, Attila AU - Buszewski, Bogusław AU - Bocian, Szymon TI - Retention mechanism on phosphodiester stationary phases in hydrophilic interaction liquid chromatography and purely aqueous mobile phase part II: Overloading with limited soluble samples JF - JOURNAL OF CHROMATOGRAPHY A J2 - J CHROMATOGR A VL - 1715 PY - 2024 PG - 12 SN - 0021-9673 DO - 10.1016/j.chroma.2023.464596 UR - https://m2.mtmt.hu/api/publication/34453833 ID - 34453833 N1 - * Megosztott szerzőség LA - English DB - MTMT ER - TY - JOUR AU - Szerencsés, Dénes AU - Sepsey, Annamária AU - Felinger, Attila TI - Correctness of the van 't Hoff analysis for homogeneous or heterogeneous retention JF - JOURNAL OF CHROMATOGRAPHY A J2 - J CHROMATOGR A VL - 1709 PY - 2023 PG - 9 SN - 0021-9673 DO - 10.1016/j.chroma.2023.464380 UR - https://m2.mtmt.hu/api/publication/34152053 ID - 34152053 N1 - Funding Agency and Grant Number: New National Excellence Program of the Ministry for Culture and Innovation [K143916, UNKP-22-3]; Gedeon Richter's Talentum Foundation in framework of Gedeon Richter Excellence PhD Scholarship of Gedeon Richter Plc.; NKFIH OTKA [K143916] Funding text: Supported by the UNKP-22-3 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund. The scientific work and results published in this article were reached with the sponsorship of Gedeon Richter's Talentum Foundation in framework of Gedeon Richter Excellence PhD Scholarship of Gedeon Richter Plc. This work was also supported by the NKFIH OTKA grant K143916. The authors thank Dr. Tivadar Farkas for the generous gift of the Phenomenex columns used in the experiments. LA - English DB - MTMT ER - TY - JOUR AU - Kazmouz, Muhamad Yahia AU - Felinger, Attila TI - The Competitive Adsorption of Water and Methanol on a Hybrid Silica Stationary Phase in Supercritical Fluid Chromatography JF - SEPARATIONS J2 - SEPARATIONS VL - 10 PY - 2023 IS - 9 PG - 13 SN - 2297-8739 DO - 10.3390/separations10090492 UR - https://m2.mtmt.hu/api/publication/34135268 ID - 34135268 N1 - ISSN:2297-8739 AB - This study investigates the adsorption of methanol, water, and their mixture in a hybrid silica stationary phase with supercritical carbon dioxide as a mobile phase in supercritical fluid chromatography (SFC). The adsorption isotherms of methanol and water were determined by two dynamic methods: the elution by characteristic point (ECP) method and the inverse method (IM). Both the single-component and competitive bi-Langmuir models were pre-selected for the inverse method. The initial parameters of the single-component isotherm for both methanol and water were estimated with the ECP method by fitting the experimental data to the bi-Langmuir isotherm model. Then, using the inverse method, we refined the single-component isotherm parameter values, which were then further used for determining the competitive isotherm of the methanol–water mixture. The elution profile of the (methanol–water) mixture sample was calculated by the equilibrium-dispersive (ED) model. The results indicated that there is a good agreement between the experimental band profile and the calculated band profile, which was obtained from the parameters of the competitive bi-Langmuir isotherm model, revealing a competition between methanol and water to reach the adsorption sites. Furthermore, the saturation capacity of the adsorption sites in the stationary phase decreased in the case of the mixture sample compared to those for the single-component sample. LA - English DB - MTMT ER - TY - JOUR AU - Sepsey, Annamária TI - An Adventurous Journey Around the Thermodynamics of Liquid Chromatography JF - LC GC NORTH AMERICA: SOLUTION FOR SEPARATION SCIENTISTS J2 - LC GC N AM VL - 40 PY - 2022 IS - 12 SP - 584 EP - 586 PG - 3 SN - 1527-5949 DO - 10.56530/lcgc.na.qk2090y9 UR - https://m2.mtmt.hu/api/publication/33567577 ID - 33567577 LA - English DB - MTMT ER - TY - JOUR AU - Rédei, Csanád AU - Felinger, Attila TI - The impact of placement, experimental conditions, and injections on mass flow measurements in supercritical fluid chromatography. JF - JOURNAL OF CHROMATOGRAPHY A J2 - J CHROMATOGR A VL - 1668 PY - 2022 PG - 7 SN - 0021-9673 DO - 10.1016/j.chroma.2022.462919 UR - https://m2.mtmt.hu/api/publication/32729411 ID - 32729411 AB - In supercritical fluid chromatography (SFC), the variation of pressure, temperature and volumetric flow-rate is most noticeable when the mobile phase contains only neat carbon dioxide. This can be explained by the compressibility of CO2 and introduces several difficulties to the work of chromatographers. The only flow parameter that is considered to be constant across the SFC system is the mass flow-rate. It has been shown that the Coriolis flow meter (CFM) provides different types of information depending on its placement in the instrument. Therefore, the goal of this paper is to investigate several factors affecting the variation of mass flow-rate in SFC, including four different configurations around the column, four sets of experimental conditions along with two columns and a zero-volume union. The effect of disturbances introduced by injections are studied as well. The results show different mass flow-rates when taken at the inlet or the outlet of the column. In addition, different columns produced different tendencies of variations. Study of the injections showed that the initial severe drop of mass flow is reduced when the averages are taken until the elution times of the chosen compounds. Additional testing related to possible leaks and CFM calibration showed that even if all standard operating procedures are strictly followed, reproducibility of the mass-flow rate can still be an issue. LA - English DB - MTMT ER - TY - JOUR AU - Kazmouz, Muhamad Yahia AU - Rédei, Csanád AU - Felinger, Attila TI - The adsorption of methanol on reversed phase stationary phases in supercritical fluid chromatography JF - JOURNAL OF CHROMATOGRAPHY A J2 - J CHROMATOGR A VL - 1653 PY - 2021 PG - 8 SN - 0021-9673 DO - 10.1016/j.chroma.2021.462386 UR - https://m2.mtmt.hu/api/publication/32095193 ID - 32095193 LA - English DB - MTMT ER - TY - JOUR AU - Zelenyánszki, Dóra AU - Felinger, Attila TI - The impact of column hardware on efficiency in liquid chromatography (LC) JF - LC GC EUROPE J2 - LC GC EUR VL - 33 PY - 2020 IS - 10 SP - 498 EP - 504 PG - 7 SN - 1471-6577 UR - https://m2.mtmt.hu/api/publication/31626827 ID - 31626827 N1 - Funding Agency and Grant Number: NKFIH OTKA [K125312]; New National Excellence Program of the Ministry of Human Capacities [UNKP-19-3-I-PTE-119] Funding text: The work was supported by the NKFIH OTKA grant K125312. The work was also supported by the UNKP-19-3-I-PTE-119 New National Excellence Program of the Ministry of Human Capacities. The authors thank Waters Corporation for the generous gift of the columns used in the experiments. The authors are grateful to Laszlo Seress and Hajnalka Abraham (Central Electron Microscope Laboratory, University of Pecs) for the electron microscopic measurements. LA - English DB - MTMT ER - TY - JOUR AU - Matarashvili, Iza AU - Chelidze, Aluda AU - Dolidze, Gizo AU - Kobidze, Giorgi AU - Zaqashvili, Nino AU - Dadianidze, Alexandre AU - Bacskay, Ivett Orsolya AU - Felinger, Attila AU - Farkas, Tivadar AU - Chankvetadze, Bezhan TI - Separation of enantiomers of chiral basic drugs with amylose- and cellulose- phenylcarbamate-based chiral columns in acetonitrile and aqueous-acetonitrile in high-performance liquid chromatography with a focus on substituent electron-donor and electron-acceptor effects JF - JOURNAL OF CHROMATOGRAPHY A J2 - J CHROMATOGR A VL - 1624 PY - 2020 PG - 11 SN - 0021-9673 DO - 10.1016/j.chroma.2020.461218 UR - https://m2.mtmt.hu/api/publication/31321664 ID - 31321664 N1 - Funding Agency and Grant Number: NKFIH OTKAOrszagos Tudomanyos Kutatasi Alapprogramok (OTKA) [K125312] Funding text: The work was in part supported by the NKFIH OTKA grant K125312 LA - English DB - MTMT ER -