scholarly journals Chromatographic Method for Evaluation of Polymeric GC Stationary Phases Ageing Using the Novel Non-Cross-Linked Poly(3-(Tributoxysilyl)Tricyclononene-7) as the Model Stationary Phase

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1899
Author(s):  
Anastasiia Kanateva ◽  
Maxim Bermeshev ◽  
Dmitrii Alentiev ◽  
Alexander A. Korolev ◽  
Alexander Kurganov
Keyword(s):  
Stationary Phase ◽  
Stationary Phases ◽  
Mass Transfer Rate ◽  
Entropy Change ◽  
The Novel ◽  
Mobile Phases ◽  
Polymeric Stationary Phases ◽  
Sorption Mechanisms ◽  
Liquid Chromatographic ◽  
Polymeric Stationary Phase

The chromatographic properties and thermal stability are investigated for the polymeric stationary phase based on the norbornene polymer. It was shown that without additional cross-linking, poly(3-(tributoxysilyl)tricyclononene-7) demonstrates properties similar to liquid chromatographic stationary phases. It was also found to be more thermally stable than previously studied trimethylsilyl- and trimethoxysilyl- derivatives. The long-term heating at 170 °C resulted in an increase of mass transfer rate between stationary and mobile phases which could be observed as a decrease of parameter C of Van Deemter equation. This effect is rather unusual, as the polymeric stationary phases tend in decrease of the layer volume and porosity while ageing. Additionally, the values of thermodynamic parameters of sorption are calculated for the polymeric stationary phase: enthalpy of sorption varied −28 to −37 kJ/mol, entropy change was −41 to −51 J/mol K. The compensation curves were plotted for the alkanes, arenes, and alcohols, and the parameters of compensation plot were calculated, demonstrating the different sorption mechanisms both for hydrocarbons and oxygen-containing compounds, and different classes of organic compounds.

scholarly journals Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

Separations ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 40
Author(s):  
María José Ruiz-Ángel
Keyword(s):  
Ionic Liquids ◽  
Stationary Phase ◽  
Mobile Phase ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Retention Mechanism ◽  
Chromatographic Behavior ◽  
Chemical Equilibria ◽  
Suppression Effect ◽  
Mobile Phases

The presence of free silanols on alkyl-bonded reversed-phase stationary phases is responsible for broad and asymmetrical peaks when basic drugs are chromatographed with conventional octadecylsilane (C18) columns due to ionic interactions. In the last few years, ionic liquids (ILs) have attracted attention to reduce this undesirable silanol activity. ILs should be considered as dual modifiers (with a cationic and anionic character), which means that both cations and anions are able to adsorb on the stationary phase, creating a positively or negatively charged layer, depending on the relative adsorption. The accessibility of basic compounds to the silanols is prevented by both the IL cation and anion, improving the peak profiles. A comparative study of the performance of six imidazolium-based ILs, differing in their cation/anions, as modifiers of the chromatographic behavior of a group of ten β-adrenoceptor antagonists, is addressed. Mobile phases containing cationic amines (triethylamine and dimethyloctylamine) were used as a reference for the interpretation of the results. Using a mathematical model based on two chemical equilibria, the association constants between the solutes and modified stationary phase as well as those between solutes and the additive in the mobile phase were estimated. These values, together with the changes in retention and peak shape, were used to obtain conclusions about the retention mechanism, changes in the nature of the chromatographic system, and silanol suppression effect.

scholarly journals Comparison of the Retention and Separation Selectivity of Aromatic Hydrocarbons with Polar Groups in RP-HPLC Systems with Different Stationary Phases and Eluents

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5070
Author(s):  
Anna Klimek-Turek ◽  
Beata Misiołek ◽  
Tadeusz H. Dzido
Keyword(s):  
Stationary Phase ◽  
Chain Length ◽  
Molecular Interactions ◽  
Aromatic Hydrocarbons ◽  
Stationary Phases ◽  
Phase Region ◽  
Separation Selectivity ◽  
Polar Groups ◽  
Rp Hplc ◽  
Mobile Phases

In this manuscript, the retention of aromatic hydrocarbons with polar groups has been compared for systems with various nonpolar columns of the types from C3 to C18 and different mobile phases composed of methanol, acetonitrile, or tetrahydrofuran as modifiers. The selectivity separation of the solutes in systems with different adsorbents, when one eluent modifier is swapped by another, has been explained, taking into account molecular interactions of the solutes with components of the stationary phase region (i.e., extracted modifier depending on the chain length of the stationary phase).

scholarly journals Separation and Bioactive Assay of 25R/S-Spirostanol Saponin Diastereomers from Yucca schidigera Roezl (Mojave) Stems

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2562 ◽  
Author(s):  
Lu Qu ◽  
Jingya Ruan ◽  
Song Wu ◽  
Peijian Huang ◽  
Jiejing Yan ◽  
...  
Keyword(s):  
Stationary Phases ◽  
Chromatographic Retention ◽  
Analysis Method ◽  
Sw620 Cell ◽  
Yucca Schidigera ◽  
Mobile Phases ◽  
Ic50 Values ◽  
C30 Column ◽  
Liquid Chromatographic ◽  
First Time

In order to find a simple, generic, efficient separation method for 25R/S-spirostanol saponin diastereomers, the liquid chromatographic retention behaviors of C12 carbonylation and C12 unsubstituted 25R/S-spirostanol saponin diastereomers on different stationary phases (C8, C18, C30 columns) and different mobile phases (MeOH-1% CH3COOH and CH3CN-1% CH3COOH) were investigated. A C30 column was firstly found to offer the highest efficiency for the separation of this kind of diastereomers than C8 and C18 columns. Meanwhile, the analysis results indicated that both CH3CN-1% CH3COOH and MeOH-1% CH3COOH eluate systems were selective for C12 unsubstituted 25R/S-spirostanol saponin diastereomers, while MeOH-1% CH3COOH possessed better selectivity for C12 carbonylation ones. Using the abovementioned analysis method, six pairs of 25R/S-spirostanol saponin diastereomers 1a–6a and 1b–6b from Yucca schidigera Roezl (Mojave) were isolated successfully by using HPLC on C30 column for the first time. Among them, three pairs were new ones, named as (25R)-Yucca spirostanoside E1 (1a), (25S)-Yucca spirostanoside E1 (1b), (25R)-Yucca spirostanoside E2 (2a), (25S)-Yucca spirostanoside E2 (2b), (25R)-Yucca spirostanoside E3 (3a), (25S)-Yucca spirostanoside E3 (3b), respectively. Moreover, 3a, 5a, 6a, 3b–6b showed strong inhibitory activities on the growth of SW620 cell lines with the IC50 values of 12.02–69.17 μM.

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