ISSN:0935-6304    

DOI:10.1002/jhrc.1240090402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractDirect analysis of polar solutes by supercritical fluid chromatography (SFC) has been somewhat limited because the mobile phases in common use are all relatively nonpolar. Derivatization is demonstrated as a viable means for facilitating the SFC separation of sugars. Oligo‐ and polysaccharides containing up to 18 glucose units are completely resolved by capillary SF

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA sample introduction system for capillary supercritical fluid chromatography, which allows the dissolution of the sample in the supercritical mobile phase before being introduced into the column, was constructed and evaluated. Supercriticaln‐pentane was shown to solvate high‐molecular‐weight polycyclic aromatic compounds that could not be solvated using typical liquid solvents. In addition, split injection of a supercritical fluid solution was found to be more reproducible than split injections of a liquid solution. The potential of such an injection system was demonstrated, although further developments are needed in order to make the technique of practically ut

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA preparative anticircular chromatography (PACH) device was constructed to elucidate different applications of separation problems as well as to compare different sample collection techniques in this particular PLC mode. An anticircular PC apparatus had to be established which allowed the utilization of 20 X 20 cm thin‐layer plates as well as sampling positioning at any given radius. Typical solvent migration times were 8–12 minutes andca.8–10 ml of solvent was needed for an entire 20 cm plate. It was shown that peak broadening effects due to diffusion during long migration could be avoided in the same way as for analytical anticircular PLC on 10 X 10 plates. On the other hand, longer migration distances allow increased resolution, in turn allowing higher sample loads, particularly in the case of trace compound enrichment. A full description of the apparatus is given, including the sampling device.Different sample collection techniques were tried and evaluated, including the through‐flow technique by on‐line center collection for plate washing as well as classical scraping‐off of interesting zones. Further evaluation of the method included quantification and evaluation of consistency by UV/VIS scanning after spot‐visualization. Several application examples are given to illustrate the efficiency of the preparative anticircul

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe present determination of selenium in biological matrices by HPTLC within situfluorimetric detection is an accurate alternative method, comparable to other established methods such as photometry, polarography, neutron activation, or X‐ray fluorescence analysis, gas chromatography, and atomic absorption spectrometry.The excellent sensitivity of this procedure is proved by the detection limit of 250 fg of selenium per spot (using purified 2,3,1‐naphthoselenodiazole). The oxidation of organic matrices, applying a novel digestion procedure, may be carried out with little instrumental expenditure.Sample preparation steps, such as the oxidation of selenium to Se (VI) and subsequent reduction to Se (IV) do not lead to significant random or systematic errors, nor does the digestion step, if an optimized procedure is used.A recovery rate of 103% and nearly parallel calibration curves for digested selenocysteine standards compared with spiked human serum samples demonstrate the accurate quantitative preparation of a biological matrix. Any interfering metal ions can be masked by addition of chelate‐forming rea

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA simple linear relationship which enables the effect of the composition of a binary mobile phase on the retention of a solute to be assessed in reverse phase liquid chromatography using a bonded stationary phase has been derived. The equations have been tested using published experimental data.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractGradient elution under hydrostatic equilibrium is extended to the treatment of the case where the two liquids have different densities. Analytic expressions are derived only for the cases where both mixing chamber and reservoir have constant cross‐sectional areas.As in the case where the densities of the liquids are equal, pressigned concentration gradients can be duplicated quite satisfactorily by combining a mixing chamber having a constant cross‐sectional area and a reservoir having an area which changes linearly with reservoir height. A numerical example is given to illustrate the use of the derived equati

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY