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Różne oblicza wodnej fazy ruchomej w chromatografii cieczowej

Dembek Mikołaj, Bocian Szymon

Wiadomości Chemiczne

2020

[Z] 74, 1-2

89--106

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.

Fazy stacjonarne do chromatografii cieczowej z wbudowanymi grupami polarnymi : synteza i właściwości powierzchniowe

Bocian S., Krzemińska K.

Wiadomości Chemiczne

2018

[Z] 72, 9-10

685--701

In recent years high performance liquid chromatography (HPLC) has gained a dominant position in the life sciences. The widespread use of this technique allows to perform an analysis of compounds which are used in various areas of human life. Currently, there are wide and fully untapped opportunities for synthesis of chromatographic packings with chemically bonded stationary phases. Some of the liquid chromatographic analyses needs the application of water-rich mobile phases (more than 85% water or a buffer). In such condition the performance of hydrophobic stationary phases indicate that the bonded ligands might be collapsing. This problem could be solved by increasing of organic content in the mobile phase which should improve solvation and bring bonded ligands back to the original conformation. To avoid this procedure, which reduces the retention and selectivity of the separation, it is possible to apply stationary phases with incorporated polar groups mixed with the original alkyl ligands (polar embedded stationary phases). Another possibility is to add some polar groups during endcapping procedure (polar end-capped stationary phases). This produces variation in the bonding. Chemically bonded stationary phases which include both hydrophobic and hydrophilic ligands are so-called mixed mode stationary pahses. These materials can be used in reversed phase liquid chromatography (RPLC) and there is also a possibility to use them in hydrophilic interaction liquid chromatography (HILIC). They allow to separate polar and non-polar analytes. 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. Surface properties of novel material were analyzed using various instrumental and chromatographic methods. Finaly, the mixtures of various compounds were applied to test the separation selectivity of stationary phases in various chromatographic system, including purely aqueous conditions.