Polymeric Functionalized Stationary Phase for Separation of Ionic Compounds by IC

Synthesis and properties are described of multilayered stationary phases containing quaternary amine functional groups used for the analysis of inorganic anions by ion chromatography. The bonded phases were characterized by elemental analysis, solid state 13C NMR spectroscopy and chromatographic methods. The surface of polyhydroxyethyl methacrylate (solid support) was coated with polymeric layers formed by condensation polymerization of primary amine with diepoxide. Each layer of the anion exchange stationary phase consisted of methylamine and 1,4-butanedioldiglycidyl ether copolymer. A series of stationary phases with different number of polymerized layers were tested. Separation of inorganic anions, such as F−, Cl−, NO2−, Br−, NO3−, were performed. Aqueous hydroxide, carbonate and bicarbonate solutions were used as mobile phases

Miscellaneous aspects of the aqueous mobile phase in liquid chromatography

Nowadays analytical chemistry, and especially chromatographic techniques, are becoming more and more popular, for example in the pharmaceutical industry [1]. Due to the increasing number of analyses, the amount of chromatographic waste is also increasing. They are harmful and toxic both to the environment and to humans. Therefore, there is a need to search for new solutions, apparatus and materials to achieve the so-called "green chromatography" [1]. Such a goal can be achieved by various methods. The most popular are miniaturization of analyses to reduce the amount of waste, reduction of analysis time, replacement of solvents with biodegradable ones, or application of aquatic conditions of analysis [2]. The following paper deals with the issue of using only water as a mobile phase for analysis in liquid chromatography. This mainly involves the use of appropriate conditions, materials and equipment. A change in the conditions of the analysis affects, first of all, the changes in the properties of water which is a mobile phase. When the temperature increases dielectric constant, viscosity and polarity of the water decreases. Optimizing these properties can allow successful separation using only water as a mobile phase [3, 4]. The following article also deals with the issue of the relatively new PALC [5] (per aqueous liquid chromatography) technique (see Fig. 3) and the analysis with the use of pure water as an eluent at room temperature, thanks to the use of polar-embedded and polar-endcapped stationary phases [6]. The latter technique is the most desirable, because it does not require the application of unusual conditions of chromatographic analysis, and at the same time fits perfectly into the assumptions of "green chromatography". The promising results of these techniques give a forward-looking view of liquid chromatography as an environmentally friendly technique

The separations using pure water as a mobile phase in liquid chromatography using polar-embedded stationary phases

Following the idea of green chemistry, especially green analytical chemistry, a series of stationary phases was synthesized. The obtained materials connect polar and hydrophobic groups in the structure of bonded ligands. These specific surface properties provide the stability of the stationary phase in pure water as a mobile phase. To confirm the solvation ability in purely aqueous mobile phases, excess isotherms of water and acetonitrile were determined. Further, the mixtures of nucleosides, nucleic bases and purine alkaloids were applied to test the separation selectivity of stationary phases in purely aqueous conditions at ambient temperature without any additives to the mobile phase. Among the four tested stationary phases, it is possible to find one for separation of each group of analytes that offers selective separation in reasonable time. The presented data confirms that it is possible to synthesize stationary phases for the separation of target mixtures in pure water conditions

Solvent Influence on Zeta Potential of Stationary Phase—Mobile Phase Interface

Zeta potential is a surface characteristic formed on the solid surface and liquid interface. It is an interesting way to describe the surface properties of materials; thus, a series of four homemade polar embedded stationary phases that contain phosphate groups incorporated into hydrophobic ligands were investigated according to surface zeta potential. Measurements were carried out using Zetasizer Nano ZS for the stationary phases suspensions prepared in various solvent and solvent binary mixtures. The negative zeta potential values were obtained for most cases due to negatively charged residual silanols and phosphate groups. However, in some solvents: tetrahydrofuran, isopropanol, and toluene zeta potential are positive. Additionally, it was observed that the zeta potential seems to be independent of the type of silica gel used for the stationary phase synthesis

Beta-Blocker Separation on Phosphodiester Stationary Phases—The Application of Intelligent Peak Deconvolution Analysis

Beta-blockers are a class of medications predominantly used to manage abnormal heart rhythms. They are also widely used to treat high blood pressure. From the liquid chromatography separation point of view, beta-blockers are interesting molecules due to their hydrophobic–hydrophilic properties. Thus, the study aimed to investigate the beta-blocker separation selectivity on four phosphodiester stationary phases in reversed-phase liquid chromatography (RP LC) and hydrophilic interactions liquid chromatography (HILIC). On tested stationary phases, beta-blockers provide retention in both chromatographic systems, RP LC and HILIC. Additionally, it was found that cation-exchange mechanisms have a significant contribution to retention. Separations were enhanced by applying ChromSword software for gradient optimization and Intelligent Peak Deconvolution Analysis to separate unseparated peaks digitally