期刊
JOURNAL OF CHROMATOGRAPHY A
卷 1560, 期 -, 页码 45-54出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.chroma.2018.05.012
关键词
Mixed-mode chromatography; Zwitterionic surface; HILIC; zeta-Potential of modified silica particles; Stationary phase classification by principal component analysis; pH-gradient driven umpolung
Herein, we present a novel silica-based stationary phase modified with N-propyl-N'-2-pyridylurea selector. Due to the weakly basic properties of the pyridine selector and the presence of residual silanols after selector immobilization, a zwitterionic surface with a pl observed at approximately pH 5.5 was measured by electrophoretic light scattering in pH-dependent zeta-potential determinations. The capability of the new N-propyl-N'-2-pyridylurea-modified silica to serve as mixed-mode stationary phase was investigated. For this purpose, it was characterized under RP and HILIC conditions using test mixtures. Subsequent classification of this stationary phase in comparison to in-house and commercial benchmarks was carried by principal component analysis of resultant retention factors from chromatographic tests. The results show a relatively unique mixed-mode character amongst the tested stationary phases. The chromatographic retention characteristics of acidic compounds matched well the zeta-potential determinations. The application of anion-exchange at low pH values (e.g. pH 5) and ion exclusion chromatography at pH 7 for the separation of uridine 5'-mono-, di- and triphosphate demonstrated a pH-dependent umpolung of the stationary phase surface. The combination of these separation principles in a pH gradient from 5 to 7 gave rise to weak anion-exchange selectivity with a charge-inducted elution due to repulsive interactions at higher pH and resulted in a significant faster separation with improved peak shape under mild elution conditions. (C) 2018 Elsevier B.V. All rights reserved.
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