Preparation and Evaluation of Long Chain Alkyl Methacrylate Monoliths for Capillary Chromatography

Abstract

This work describes the fabrication of long chain alkyl methacrylate monolithic materials for use as stationary phases in capillary liquid chromatography. After capillary inner wall surface activation with 3-(trimethoxysilyl)propyl methacrylate, monoliths were formed by copolymerization of either lauryl or stearyl methacrylate (LMA or SMA) with ethylene dimethacrylate (EDMA) as crosslinker, in the presence of azobisisobutyronitrile (AIBN) as initiator and a mixture of porogenic solvents including water, 1-propanol and 1,4-butanediol. The composition of the polymerization mixture was changed in terms of monomer, crosslinker and porogen ratio composition, in order to compare the influence of these parameters. The monoliths were prepared in 320 lm i.d. and 200 mm length capillaries. The column morphology was characterized by optical microscopy and scanning electron microscopy (SEM). Total porosity and permeability of each column were calculated using uracil as unretained material by measuring the pressure drop across the columns as a function of linear velocity. The microglobule average size for each column was also determined using Hagen-Poiseuille equation and compared with the SEM images. As expected, a decrease of the porogen to monomer ratio corresponded to smaller microglobules and a lower total porosity. The columns were then chromatographically evaluated; good results were obtained when these capillaries were used to separate mixtures of phenols, aromatics and drug compounds.

Separation of Inorganic Anions Using Methacrylate-Based Monolithic Column Modified with Trimethylamine in Ion Chromatography Capillary System

“…In recent years, monolithic columns have attracted much attention as the separation media in chromatography. Monolithic columns in capillary liquid chromatography were introduced by Hjerten, et al in 1989, and since that time, monolithic columns have rapidly become highly popular [7]. Monolithic columns have many unique properties.…”

Desenvolvimento e caracterização de fases estacionárias monolíticas à base de octadecilmetacrilato para uso em eletrocromatografia capilar

“…A mistura de solventes porogênicos utilizada foi de álcool isoamílico: Além das colunas descritas anteriormente, Karenga e El Rassi [117] desenvolveram monolitos com ligantes mistos para uso em CEC por fase reversa. Neste trabalho, fases monolíticas do tipo C18, preparadas a partir do monômero octadecilmetacrilato, foram desenvolvidas para suprir a escassez de estudos acerca do assuntoa baixa solubilidade em meio aquoso de monômeros de metacrilato de longa cadeia hidrofóbica [74,139,144,147], que muitas vezes exige a inserção de surfactantes para que seja possível a formação de uma fase líquida e homogênea para preenchimento da coluna capilar [13,94], sendo este o principal entrave para o desenvolvimento destas fases estacionárias. Além disso, a necessidade de inserção de um monômero com carga para geração de EOF na coluna capilar dificulta a solubilização do octadecilmetacrilato com este monômero hidrofílico [159].…”