Colunas de alta eficiência cromatográfica de origem monolítica orgânica foram obtidas para uso em eletrocromatografia capilar (CEC) utilizando uma mistura de monômeros (concentrações constantes) com diferentes proporções de solventes porogênicos (1,4-butanodiol com álcool isoamílico, álcool amílico ou cicloexanol, na presença ou ausência de água). As fases estacionárias foram preparadas a partir do monômero precursor octadecilmetacrilato (ODMA), do agente de entrecruzamento etilenodimetacrilato (EDMA) e do monômero carregado ácido 2-acriloilamido-2-metilpropanosulfóxido (AMPS), sendo este necessário para tornar a fase estacionária carregada negativamente, garantindo o fluxo eletrosmótico durante a análise. As colunas monolíticas foram caracterizadas fisicamente através de porosimetria e microscopia eletrônica de varredura (SEM), e eletrocromatograficamente, através de cálculo dos parâmetros cromatográficos de separação. A coluna mais eficiente foi preparada a partir dos solventes porogênicos álcool amílico:1,4-butanodiol na proporção 65:35 (v/v) e apresentou 38 µm de altura de prato. Estas colunas foram aplicadas na separação de alquilparabenos e hidrocarbonetos policíclicos aromáticos (PAH).Organic monolithic columns with high efficiency were obtained for use in capillary electrochromatography (CEC) from a mixture of monomers (constant concentrations) with different proportions of porogenic solvents (1,4-butanediol with isoamyl alcohol, amyl alcohol or cyclohexanol in the presence or absence of water). The stationary phases were prepared from the precursor monomer octadecyl methacrylate (ODMA), the cross-linking agent ethylene dimethacrylate (EDMA) and the ionizable monomer 2-acryloylamido-2-methylpropanesulfonic acid (AMPS), the latter being necessary to make the stationary phase negatively charged, assuring electrosmotic flow (EOF) during analysis. The monolithic columns synthesized were physically characterized by porosimetry and scanning electron microscopy (SEM), and electrochromatographically characterized by calculation of chromatographic parameters. The most efficient column was prepared using the porogenic solvent amyl alcohol:1,4-butanediol in a 65:35 (v/v) ratio and showed a plate height of 38 µm. These columns were applied for the separation of alkyl parabens and polycyclic aromatic hydrocarbons (PAH).
Keywords: capillary electrochromatography, monolithic stationary phases
IntroductionCapillary electrochromatography (CEC) is a hybrid technique of capillary electrophoresis (CE) and high performance liquid chromatography (HPLC).1,2 The CEC technique can be defined as a type of capillary electrophoresis carried out in packed capillary columns in an environment in which an applied electric field is responsible for the movement of the mobile phase across the capillary, generating the electrosmotic flow (EOF).3 Different from separations in zone capillary electrophoresis, the use of the stationary phase results in the separation of uncharged sample components. The major advantage of CEC compared to HPLC i...