Investigating the Retention Mechanisms and Types of Secondary Interactions Determining the Influence of Structural Fragments of Novel HILIC Materials on Their Selectivityтезисы докладаТезисы
Дата последнего поиска статьи во внешних источниках: 26 января 2022 г.
Аннотация:Since the selectivity of HILIC stationary phases is crucial for choosing a stationary phase for separatingtarget compounds, it’s important to find out the particular effect of a certain functional group or a linker onthe chromatographic performance of the material. Revealing the respective trends can help to develop theways of regulating the interactions of the stationary phase with target analytes and constructing novelmaterials with improved selectivity toward the particular classes of polar compounds. One of the mostrepresentative methods for versatile comparison of stationary phases is an examination procedure for HILICmaterials known as Tanaka test, which allows one to explore different types of selectivity and thus toobserve specific secondary interactions of analytes with an adsorbent. In the present work a step-by-stepconstruction of novel HILIC stationary phases was performed with consistent variations in theirfunctionalities using different linkers, functional groups of diverse nature such as amines, polyamines ofdifferent hydrophilicity, diol-, zwitterionic groups differing in their structure and acidity, as well as variationsin grafted polymer layer structure by means of its hydrophilization, quaternization, and crosslinking. Tanakatests were used to characterize the whole set of home-made HILIC materials in addition to the study of theirretention characteristics obtained for model mixtures of various analytes (sugars, water-soluble vitamins,and amino acids, including positively charged arginine, histidine, lysine). Synthesized phases werecharacterized in terms of selectivity for methylene and hydroxyl groups, configurational isomers, ionexchangeinteractions, and their acidic-basic nature. All adsorbents were also tested for re-equilibrationtime to establish their tolerance to gradient elution mode. The obtained results allowed us to reveal, whichparticular changes in the structure of the HILIC phases (and to which extent) are responsible for theirdifferences in chromatographic performance. In particular, the type of surface coverage leading to theincrease in hydrophilicity was established. Comparison of ion-exchange properties of the synthesizedphases revealed unexpected ion-exchange selectivity in some cases for the phases that tended to haveneutral surface. It allowed us to find the ways of regulating their cation- and anion-exchange propertiescaused by the certain fragments in the structure responsible for ion-exchange mechanism. Tanaka tests provided the possibility to classify the set of 15 home-made HILIC phases and reveal impacts of certainstructural fragments of the material on its selectivity, which could be useful for developing the ways ofconstructing multifunctional HILIC stationary phases selective for broader range of analytes.
