Premium
Columns and optimum gradient conditions for fast second‐dimension separations in comprehensive two‐dimensional liquid chromatography
Author(s) -
Hájek Tomáš,
Jandera Pavel
Publication year - 2012
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201200061
Subject(s) - chromatography , dimension (graph theory) , resolution (logic) , two dimensional chromatography , chemistry , fraction (chemistry) , gradient elution , analytical chemistry (journal) , elution , range (aeronautics) , sample (material) , reversed phase chromatography , phase (matter) , high performance liquid chromatography , biological system , materials science , mathematics , computer science , artificial intelligence , pure mathematics , composite material , biology , organic chemistry
Gradient elution provides significantly higher peak capacity in comparison to the isocratic elution mode, hence it is very useful in online comprehensive two‐dimensional liquid chromatography ( LC ). We compared suitability of five commercial core‐shell columns and one monolithic column for fast gradients in the second LC dimension, where the time of separation is strictly limited by the fraction cycle time. In two‐dimensional reversed‐phase systems with partially correlated retention, the resolution, the peak capacity, and the regularity of coverage of the second‐dimension retention space can be improved by appropriate adjusting the gradient time and the gradient range to suit the sample properties. We developed a new strategy for adjusting the gradient mobile phase composition range in the second‐dimension, employing the retention data of representative sample standards characterizing the sample properties, which can be calibrated using the reference alkylbenzene series. Optimized second‐dimension gradients with single‐step or segmented profiles covering two or more fraction ranges, employed for the separation of subsequent fractions from the first‐dimension, improve significantly the resolution, the separation time, and the regularity of coverage of the two‐dimensional retention plane. The approach was applied to the two‐dimensional comprehensive separation of phenolic acids and flavonoid compounds occurring as natural antioxidants.