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The preparation of porous polymethacrylate-based open tubular capilary columns by in-situ copolymerization of octadecyl methacrylate (OMA), and ethylene dimethacrylate (EDMA) in N,N-dimethylformamide (DMF) solvent are proposed. The parameters of the preparation procedure of the stationary phase are discussed in detail. The surface of the cross-section of an open tubular (OT) column by scanning electron microscope (SEM) showed wrinkle configuration, which is expedient to enhance proportion of stationary phase and column capacity. Efficient separation of six alkyl benzene homologous series (namely, toluene, ethylbenzene, propylbenzene, butylbenzene, amylbenzene and hexylbenzene) were performed by CEC using the prepared column, and their elution order was in agreement with their hydrophobicity. So, the OT columns bonded with octadecyl ligands yielded reversed-phase retention behavior toward nonpolar solutes. In addition, the separation of four antiepileptics was also investigated with satisfactory effectiveness. The column efficiency range was 35 300-49 800 plates/m. The results showed that the C18-OT column of organic matrix for reversed-phase chromatography was successfully prepared via in-situ polymerization in this work. Hereby, this new column thus offers a promising new alternative in OT-CEC and will be useful in separation science.

A chiral monolithic capillary column for rapid enantioseparation was prepared by covalently bonding of cellulose tris(4-methylbenzoate) (CTMB) on N-acryloxysuccinimide-based monolith. The preparation and derivatization conditions of the monolithic column were optimized. The successful grafting of CTMB was confirmed on the characterizations of the infrared spectrum and the cathodic electroosmotic flow (EOF). The effects of acetic acid concentration and methanol content on the enantioseparation were studied. The solvent resistance, reproducibility and stability of the monolithic column have also been investigated. The rapid enantioseparation of the five solutes (phenylalanine, tyrosine, tryptophan, propranolol and phenylethanol) with resolution (R(s)) values up to 1.31 was achieved within 1.2 min on the prepared chiral capillary monolithic column by capillary electrochromatography.

Via covalent coupling of epoxy group, an open tubular column covalently modified with carboxymethyl chitosan (CMC) as stationary phase was prepared. The parameters of column pretreatment, silanization and chemically bonding of CMC were optimized. The morphology of inner wall of the open tubular column was observed by scanning electron microscope (SEM), which showed that the inner wall of the prepared column was evenly coated with a polymer film. Either positive or negative electroosmotic flow (EOF) could be achieved by varying the pH values of running buffer. Good reproducibility was obtained with the relative standard deviations (RSDs) of EOF less than 0.8% for run-to-run (n = 6), less than 3.5% for day-to-day (n = 3), less than 4.3% for column-to-column (n = 3) and less than 6.1% for batch-to-batch (n = 3). Nucleotides (AMP, GMP, CMP and UMP) were analyzed on the open tubular column modified with CMC, with high column efficiencies ranging from 36 000 to 182 000 plates/m. The results indicate that the developed method is effective, easy and stable.

A hydrophilic monolithic column was prepared by in-situ polymerization of 2-hydroxyethyl methacrylate (HEMA) as a functional monomer and ethylene glycol dimethacrylate (EDMA) as a cross-linking agent in the fused-silica capillary. The monolithic column was evaluated as a hydrophilic interaction capillary electrochromatography (HI-CEC) stationary phase for polar solutes. The polar sites on the surface of the monolithic stationary phase responsible for hydrophilic interactions were provided from the hydroxy groups on the surface of the monolithic stationary phase. These polar functionalities also attract ions from the mobile phase and impart the monolithic stationary phase with a given zeta potential to generate electroosmotic flow (EOF). The characterization and the performance of the poly(HEMA-co-EDMA) monolithic column were carried out. The electrochromatographic retention behaviors of polar solutes were investigated and the retention mechanism was also studied. Hydrophilic interaction was observed at high acetonitrile content ( > 62%, v/v). The results also show that the monolithic column can effectively separate polar solutes including phenols, benzoic acids, anilines, nucleosides and nucleic acid bases under HI-CEC mode.

Hydrophilic interaction capillary electrochromatography (HI-CEC) is one of the hot spots in micro-separation technique, and the research of HI-CEC stationary phase has attracted much attention. In this paper, the research progress of open-tubular column, the particle-packed column and the monolithic column for HI-CEC are reviewed, especially for the recent progress of the monolithic CEC.

A novel hydrophilic interaction capillary electrochromatographic (HI-CEC) monolith with covalently bonded zwitterionic functional groups was applied for the separation of riboflavins (RF) and its derivatives. With a homemade pressurized capillary electrochromatography-laser induced fluorescence detection (pCEC-LIF) system, trace levels of RF and its derivatives, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), can be baseline separated within 8.0 min in isocratic elution mode. The effect of experimental parameters on separation was investigated. Under the optimum conditions, analytes could be determined over nearly three orders of magnitudes with the detection limits (LODs) as low as 5.0 x 10(-11) mol/L (RF), 8.0 x 10(-10) mol/L (FMN), 2.5 x 10(-9) mol/L (FAD), and the relative standard deviations (RSDs) were less than 8.2%. This method is rapid, simple, repeatable and more sensitive than the most of reported methods, and satisfied results has been achieved in serum sample. Furthermore, it can be further applied for trace analysis of RF and its derivatives in biological fluid and cells.