Rapid capillary electrochromatographic profiling of phytohormones on a hydrophilic interaction/strong anion-exchange mixed-mode monolith

An improved hydrophilic interaction/strong anion-exchange (HI-SAX) monolith for rapid capillary electrochromatographic profiling has been developed to detect carboxylic phytohormones with high resolution. The HI-SAX monolith was prepared by copolymerization of 2-(methacryloyloxy) ethyltrimethylammonium methyl sulfate, pentaerythritol triacrylate and porogenic solvents. Detailed polymerization compositions were investigated and improved, and the characteristics in terms of morphology, retention mechanism and column reproducibility were studied. A typical hydrophilic chromatography mechanism was observed when ACN content exceeded 30%, and the HI-SAX mixed-mode was verified with nucleic acid bases and nucleosides. Based on the improved HI-SAX monolith, capillary electrochromatographic profiling of typical phytohormones was evaluated by using indole-3-acetic acid (IAA), abscisic acid (ABA) and gibberellic acid (GA(3)) as the mode analytes. Effects of the test parameters on carboxyl phytohormones were investigated, and a fast analysis with high resolution for the representative phytohormones was achieved within 4.0 min with intraday RSDs (n = 3) less than 2.6% and 6.3% for the retention time and peak area, respectively. When applied to spiked corn samples, mean recoveries between 82.3% and 95.4% were obtained.