作者：
Phinney, KWNIST
Chem Sci & Technol Lab Analyt Chem Div Gaithersburg MD 20899 USA
The pharmaceutical industry has largely been the driving force behind the development of chiral separation techniques. The transition from from traditional batch processes to simulated moving bed (SMB) technology has ...
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The pharmaceutical industry has largely been the driving force behind the development of chiral separation techniques. The transition from from traditional batch processes to simulated moving bed (SMB) technology has dramatically changed the acceptance of chromatography for large-scale production. Capillary electrophoresis continues to grow in popularity for enantioselective separations, although reproducibility and sensitivity remain issues of concern. Applications of supercritical fluid chromatography (SFC) to enantioselective separations have also expanded because of SFC offers an attractive alternative to liquid chromatographic techniques.
The separation of biological mixtures in open microchannels using electrophoresis with rapid and simple coupling to mass spectrometry is introduced. Rapid open-access channel electrophoresis employs microchannels that...
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The separation of biological mixtures in open microchannels using electrophoresis with rapid and simple coupling to mass spectrometry is introduced. Rapid open-access channel electrophoresis employs microchannels that are manufactured on microchips. Separation. is performed in the open channels, and the chips are transferred to a matrix-assisted laser desorption/ionization (MALDI) source after the solvent is evaporated. The matrix (2,5-dihydroxybenzoic acid) is placed in the solution with the run buffer before the separation of the analyte components, After separation, the solvent is evaporated and the microchip is ready for MALDI-MS analysis. The microchip is placed directly into a specially designed ion source of an external source Fourier transform mass spectrometry instrument. Separation of simple mixtures containing oligosaccharides and peptides is shown.
Separations of naphthalene compounds that differ in position of substitution and type of substituent were accomplished using cyclodextrin distribution capillary electrochromatography. Separation systems composed of ru...
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Separations of naphthalene compounds that differ in position of substitution and type of substituent were accomplished using cyclodextrin distribution capillary electrochromatography. Separation systems composed of running buffers containing mixtures of native neutral and single isomer anionic cyclodextrins (CDs) were employed yielding efficiencies of approximately 200 000 plates/meter. Solute migration rates and relative orders can be readily modified by changing CD types and concentrations, Experiments were performed to determine distribution coefficients between each of the CDs used in these studies and an aqueous running buffer. For this work, naphthalene-CD cavity inclusion is assumed to be the principal mode of interaction. The distribution coefficients for carboxymethyl-beta-cyclodextrin (CM-beta-CD), degree of substitution 1, were 10-70% larger than those for native beta-CD and 75-1800% larger than those for gamma-CD. The CM-beta-CD was singly charged and yielded a narrow elution window, Nevertheless, baseline resolution was achieved for several substituted naphthalene compounds using CM-beta-CD in conjunction with beta-CD or gamma-CD Under certain conditions, the gamma-CD system yielded an elution order that differed from that of the beta-CD system. Heptakis-(2,3-dimethyl-6-sulfato)-beta-CD with its -7 charge produced a much larger elution window. The extensive substitution with sulfonic groups at the truncated bottom of the CD seemed to inhibit inclusion as the distribution coefficients for the naphthalene compounds were generally more than an order of magnitude smaller than those for CM-beta-CD. Moreover, there was evidence that this sulfato-CD interacted with both the capillary wall and neutral beta-CD. This work differs from prior uses of CDs in that relatively complicated mixtures of neutral, achiral compounds are separated using combinations of recently developed single-isomer CDs as running-buffer additives. The single-isomer CDs, as opposed to most
The acute toxicities of 19 substituted benzene compounds and intermediates of pesticides to Photobacterium phosphoreum in beta -CD aqueous solution ( 5 g / L) were studied and compared with those in water through lumi...
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The acute toxicities of 19 substituted benzene compounds and intermediates of pesticides to Photobacterium phosphoreum in beta -CD aqueous solution ( 5 g / L) were studied and compared with those in water through luminescent bacteria toxicity test, and 15min-EC50 values were obtained. The presence of beta -CD significantly reduce biotoxicities of the low-polarity compounds, while for the higher-polarity compounds, such effect was slight. The differences of biotoxicities were correlated with Log(10)Kow ( octanol / water partition coefficients). A significant linear relationship was obtained with some abnormal data picked out. Some explanations concerning molecular structure of chemicals as well as beta -CD were given for the relationship. (C) 1998 Elsevier Science Ltd. All rights reserved.
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