scholarly journals Hydrophilic Liquid Chromatography versus Reversed-Phase Liquid Chromatography in the Absence and the Presence of 1-Hexyl-3-methylimidazolium Chloride for the Analysis of Basic Compounds

Separations ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 30
Author(s):  
Ester Peris-García ◽  
Raquel Burgos-Gil ◽  
María Celia García-Alvarez-Coque ◽  
María José Ruiz-Angel
Keyword(s):  
Liquid Chromatography ◽  
Stationary Phases ◽  
Adsorbed Water ◽  
Reversed Phase ◽  
Chromatographic Behavior ◽  
Peak Shape ◽  
Reversed Phase Liquid Chromatography ◽  
Basic Compounds ◽  
Phase Liquid ◽  
Phase Surface

In reversed-phase liquid chromatography (RPLC), positively charged basic compounds yield broad and asymmetric peaks, as a result of ionic interactions with free silanols that remain on conventional silica-based columns. Diverse solutions have been proposed to mask the silanophilic activity, which is translated to an improved peak shape. In this work, the chromatographic performance of hydrophilic interaction liquid chromatography (HILIC) was evaluated as an alternative to the addition of an ionic liquid (IL) to the aqueous-organic mobile phase used with RPLC columns, for the analysis of eight β-adrenoceptor antagonists. ILs change the behavior of RPLC stationary phases owing to adsorption on their surface. Meanwhile, in HILIC, a layer of adsorbed water is formed on the stationary phase surface. The association of cationic basic compounds with the adsorbed additive ions, hydrophilic partitioning on the HILIC columns, and other interactions, give rise to complex retention mechanisms. The chromatographic behavior was examined in terms of retention, elution strength, selectivity, peak shape and resolution, using acetonitrile-water mobile phases buffered at pH 3. Both chromatographic modes, RPLC with added IL and HILIC, proved to be a viable solution to the problem of poor peak shape for basic compounds.

scholarly journals Static vs. Dynamic Electrostatic Repulsion Reversed Phase Liquid Chromatography: Solutions for Pharmaceutical and Biopharmaceutical Basic Compounds

Separations ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 59
Author(s):  
Giulia Mazzoccanti ◽  
Francesco Gasparrini ◽  
Andrea Calcaterra ◽  
Claudio Villani ◽  
Alessia Ciogli
Keyword(s):  
Liquid Chromatography ◽  
Stationary Phases ◽  
Protonated Form ◽  
Reversed Phase ◽  
Electrostatic Repulsion ◽  
Reversed Phase Liquid Chromatography ◽  
Peptide Purification ◽  
All Solutions ◽  
Basic Compounds ◽  
Phase Liquid

Many efforts have been made to separate basic compounds, which are challenging to resolve in reversed phase liquid chromatography. In this process, they are strongly retained and the peak shape undergoes significant distortion. The principal origin of this has been identified with the non-negligible interaction with residual deprotonated silanols. Consequently, all solutions that efficiently shield silanols are being sought. This review is an upgrade on the use of the electrostatic repulsion reversed phase (ERRP) approach: retention of bases, in protonated form, can be achieved by modulating the charge repulsion caused by the presence of positive charges in the chromatographic system. This study successfully (i) introduced fixed positive charges in the structure of stationary phases, (ii) used cationic and hydrophobic additives in the mobile phase, and (iii) used the ERRP-like approach employed at the preparative level for peptide purification.

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