Controlling selectivity of polymer-based monolithic stationary phases
1
Martina Komendová, 2
Luiz Fernando Ribeiro, 1
Jiří Urban
1
Masaryk University, Department of Chemistry, Brno, Czech Republic
2
Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748 - 05508-000, São Paulo, Brazil
In this work, we aimed in the preparation of monolithic capillary column allowing an isocratic
separation of ten dopamine precursors and metabolites in a single run. Segments of five
zwitterion sulfobetaine polymer monoliths have been modified by zwitterion phoshorylcholine
by using a UV-initiated two-step photografting. Columns with 0, 33, 50, 66, and 100% of modified
length were prepared. Effect of the length of the modified segment and mobile phase
composition have been tested. All columns provided dual-retention mechanism with reversedphase
retention in highly aqueous mobile phase and hydrophilic interaction mechanism in highly
organic mobile phase. Retention mechanism was controlled by a composition of the mobile phase
and has been described by a three-parameter model. We have used regression parameters to
characterize the retention of analyzed compounds and to study individual pathways of dopamine
metabolism. Comprehensive optimization of mobile phase composition allowed to find an
optimal composition of the mobile phase and stationary phase surface chemistry arrangement to
achieve desired separation. Optimized columns provided an isocratic separation of all tested
compounds in less than nine minutes.