Separation of histidine enantiomers by capillary electrochromatography with molecularly imprinted monolithic columns

Abstract

In this study, we aimed to separate the enantiomeric forms of d,l‐histidine, one of the essential amino acids, through molecular imprinted monolithic capillary electrochromatography columns prepared using hydrophobic N‐methacryloyl‐(l)‐phenylalanine methyl ester as the functional monomer, and l‐histidine as the template molecule. We investigated the effect of monomer ratio, temperature, template molecule mole ratio, crosslinker ratio, and porogen ratio to improve the permeability properties of the monolithic column. Characterization studies of the column were evaluated by attenuated total reflectance‐Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. The chromatographic performance of the column was investigated using alkylbenzene‐derived compounds. We evaluated some parameters to determine the optimum conditions for electrochromatographic studies such as electric field, organic solvent ratio, and pressure effect. The calculated imprinting factor (2.18) proved that the l‐histidine imprinted amino acid‐based monolithic column separated d,l‐histidine molecules efficiently (percent relative standard deviation < 1.5) from each other using molecular imprinting technique with high‐resolution values (resolution value > 1.5). As a result, selective d,l‐histidine separation was achieved in less than 10 min at pH 7.0 without using a ligand or extra modification step for the first time.

Chiral Separations by Capillary Electrophoresis and related Techniques with Different Chiral Selectors: A Review

“…Wu et al prepared MIPs containing magnetic nanoparticles combined with the microchip-CEC method to be used as CSP to separate mandelic acid and histidine enantiomers [104]. Denizli et al prepared amino acid-imprinted monolithic columns to perform enantiomeric separations of hydrophobic amino acids (tryptophan, phenylalanine and tyrosine) and histidine enantiomers in CEC [105,106]. While L-forms of amino acids are preferred as template molecules, N-methacryloyl-(L)-phenylalanine (MAPA) monomer was preferred as a functional monomer to implement the MIT.…”

“…Methacrylate-based monolithic columns are one of the materials most prone to development. In addition to being practical, it is shown that the column can be applied sometimes without requiring any silanization pro-cess [105,106,[321][322][323] Denizli et al synthesized chiral monolithic capillary column based on butyl methacrylate in their studies in which the enantiomeric separations of including some of hydrophobic amino acids investigated, which N-Metacryloyl-L-Histidine monomer (MAH) and N-Metacryloyl-L-Glutamic Acid (MAGA) was used as chiral selectors, resptectively in CEC [324,325].…”

Separation of enantiomers by open‐tubular capillary electrochromatography using (R)‐1,1′‐bi‐2‐naphthol derivatives as chiral stationary phases

“…CEC is an excellent technology for separation and analysis that integrates classical CE and modern micro-column separation. CEC works using the same separation mechanism of chiral stationary phases of HPLC [1][2], but with the electrokinetic sample transport of CE [3][4][5][6], the method is able to separate charged and neutral substances [7][8][9][10]. The use of EOF to propel the mobile phase avoids, the peak broadening in classical HPLC that results from uneven flow velocity when pressure is used to drive the Article Related Abbreviations: BINOL, (R)-1,1′-bi-2-naphthol; DPPF, 1,1′-bis(diphenyl-phosphino)ferrocene; TEMED, N,N,N',N'-tetramethyl-ethylenediamine; TGA, thermogravimetric analysis fluid.…”

Synthesis of molecularly imprinted magnetic nanoparticles for selective cytidine adsorption

“…The molecular imprinting technique has been utilized to prepare synthetic polymers with specific cavities. These synthetic polymers can recognize template molecules according to size, shape, and chemical functionality because of their specific cavities [12][13][14][15]. The molecular imprinting technique allows the synthesis of selective polymeric receptors with simple use and reusability.…”