betadex and 1-methylimidazole

A simple, comprehensive, and efficient capillary electrophoresis method using a self-synthesized ionic liquid [N-methylimidazole-β-cyclodextrin] [bromide] as a separation selector was developed for the simultaneous separation and determination of five chlorogenic acid isomers (chlorogenic acid, cryptochlorogenic acid, neochlorogenic acid, isochlorogenic acid A, isochlorogenic acid B). After optimization of separation conditions, the electrolyte solution was 50 mM ammonium acetate buffer containing 0.7% (w/w) ionic liquid [N-methylimidazole-β-cyclodextrin] [bromide] (pH 4.8), 15 kV of the electric field was applied at 25°C, and the detection wavelength was at 237 nm. Under the optimal separation conditions, good linearities were obtained with linear correlation coefficients of the five analytes of 0.9994-0.9998, and the limits of detection and the limits of quantification were 0.6-2.8 and 2.2-9.5 μg/ml. Excellent accuracy and precision were obtained for the five analytes. The intraday and interday precision of standards ranged from 0.5 to 1.3% and from 1.2 to 1.9%. The intraday and interday precision of samples ranged from 1.0 to 1.9% and from 1.2 to 2.6%. The sample recovery rates were between 98.0 and 101.8%. This method was successfully applied for the analysis of five components in Honeysuckle Chinese medicinal preparations. The mechanisms involved in the separation of five analytes by [N-methylimidazole-β-cyclodextrin] [bromide] were discussed.

Topics: beta-Cyclodextrins; Bromides; Chlorogenic Acid; Electrophoresis, Capillary; Imidazoles; Ionic Liquids; Lonicera; Stereoisomerism

Electrospray ionization (ESI) mass spectrometry was utilized to investigate noncovalent complexes between beta-cyclodextrin (beta-CD) and five novel polyamide acids containing N-methylpyrrole and N-methylimidazole. The 1:1 binding mode was specified by examining the binding stoichiometry from ESI mass spectra. It found that polyamide acids with beta-CD have binding affinities in the order: ImImImbetaCOOH > ImPyImbetaCOOH > ImPyPybetaCOOH > PyPyPybetaCOOH > NO(2)PyPyPybetaCOOH. The method gives, simultaneously, the binding constants between beta-CD and polyamide acids based on a novel linear equation.

Topics: Algorithms; beta-Cyclodextrins; Imidazoles; Linear Models; Nylons; Pyrroles; Spectrometry, Mass, Electrospray Ionization

Two simple interfaces were designed and realized, enabling on-line coupling of microfluidics reactor chips to a nanoflow electrospray ionization (NESI) time-of-flight (TOF) mass spectrometer (MS). The interfaces are based on two different approaches: a monolithically integrated design, in which ionization is assisted by on-chip gas nebulization, and a modular approach implying the use of commercially available Picospray tips. Using reserpine as a reference compound in a 1ratio1 mixture of acetonitrile and water revealed that both interfaces provide a remarkably stable mass spectrometric signal (standard deviations lower than 8% and 1% for the monolithic and modular approaches, respectively). Glass microreactors, containing mixing zones, were fabricated and coupled to the modular interface with perfluoroelastomer Nanoport fluidics connectors, providing a tool to study chemical reactions on-line. Investigation of the mixing dynamics showed that complete on-chip reagents mixing is achieved within a few tens of milliseconds. Metal-ligand interactions of Zn-porphyrin with pyridine (2), 4-ethylpyridine (3), 4-phenylpyridine (4), N-methylimidazole (5), and N-butylimidazole (6) in acetonitrile as well as host-guest complexations of beta-cyclodextrin (7) with N-(1-adamantyl)acetamide (8) or 4-tert-butylacetanilide (9) in water were studied by mass spectrometry using the modular NESI-chip interface. From on-chip dilution-based mass spectrometric titrations of Zn-porphyrin 1 with pyridine (2) or 4-phenylpyridine (4) in acetonitrile Ka-values of 4.6 +/- 0.4 x 10(3) M(-1) and 6.5 +/- 1.2 x 10(3) M(-1), respectively, were calculated. The Ka-values are about four times larger than those obtained with UV/vis spectroscopy in solution, probably due to a higher ionization efficiency of complexed compared to uncomplexed Zn-porphyrin. For the complexation of N-(1-adamantyl)acetamide (8) with beta-cyclodextrin (7), a Ka-value of 3.6 +/- 0.3 x 10(4) M(-1) was obtained, which is in good agreement with that determined by microcalorimetry.

Topics: Acetanilides; Acetonitriles; Amantadine; beta-Cyclodextrins; Calorimetry; Electrophoresis, Capillary; Electrophoresis, Microchip; Gases; Imidazoles; Ions; Kinetics; Ligands; Mass Spectrometry; Metals; Microfluidic Analytical Techniques; Microscopy, Fluorescence; Models, Chemical; Nanotechnology; Porphyrins; Protein Array Analysis; Pyridines; Reserpine; Software; Spectrometry, Mass, Electrospray Ionization; Time Factors; Water; Zinc