Separation of hydrophobic amino acid enantiomers in CEC (capillary electrochromatography) system by molecular imprinting technique

Because of their ability to show different biological activities, the separation of enantiomers is of importance in the field of chromatographic research in chemistry. Amino acid enantiomer pairs have become one of the important research topics in recent years due to factors such as increasing commercial importance and being easily accessible. The achievement of high resolution separations of amino acids is an important application point in amino acid analysis. Many of the amino acid enantiomers can be used as starting materials in the synthesis process of biologically active compounds or as complements of various tasks. There are various methods for separating of chiral compounds. There are various methods for separating chiral compounds. Capillary electrochromatography (CEC) method was used as one of the electrophoresis techniques. The CEC method is based on the high selectivity of High Performance Liquid Chromatography (HPLC) and the efficient discrimination of capillary electrophoresis (CE) and is one of the most efficient methods in recent years as the resultant compounding technology. Because of the different hydrodynamic properties that it possesses, monolithic columns in the CEC system are preferred over filled columns. Polymer columns from groups of monolithic columns can be prepared with various organic monomers. Molecularly imprinted polymers (MIPs) can be easily prepared in practical terms as materials suitable for molecular identification. In addition, these polymers have mechanical properties, robustness against heat and pressure, physical stability, acidic, basic, metal-ions and organic solvents. In this thesis, it was aimed to separate the enantiomeric forms of hydrophobic amino acids by molecular imprinting technique in CEC system. In this target, the hydrophobic N-Methacryloyl-(L) -phenylalanine monomer was preferred as the functional monomer, while the monolithic CEC column with hydrophobic character was prepared, while the L-form of amino acid was selected as the template molecule to be imprinted. In order to increase the permeability properties of the prepared methacrylate-based monolithic column, monomer ratio, temperature effect, template molecule ratio, crosslinking ratio, porogen ratio and type was examined. Characterization studies of the prepared CEC column were evaluated by FTIR-ATR, SEM and BET analyzes. After obtaining optimal permeability, the chromatographic performance of the monoliths was determined using alkyl benzene-derived compounds. To determine the optimum conditions, enantiomeric separations were carried out under different conditions for the effect of the concentration of the stream, the pressure, the organic solvent and the determination of the enantiomeric stream. Theoretical plate values and theoretical plate heights were calculated to support the results. After carrying out the reusability studies, the separation performance of the molecularly imprinted column and the non-imprinted column was compared electrochromatographically. With the use of monolithic CEC column with hydrophobic character, the enantiomeric separations of the hydrophobic amino acids tryptophan, tyrosine and phenylalanine in CEC system were successfully carried out.