ISSN:0935-6304    

DOI:10.1002/jhrc.1240150802

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe enantiomers of 2‐chloropropionic acid methyl ester,cis‐pinane, 2‐bromoethylbenzene, 2‐bromobutane, 2‐hydroxybutane trifluoroacetyl ester, and styrene oxide have been resolved on an octakis‐(3‐O‐butyryl‐2,6‐di‐O‐pentyl)‐γ‐cyclo‐dextrin capillary column, and the separation of the styrene oxide enantiomers has also been studied on columns coated with octakis‐(3‐O‐trifluoroacetyl‐2,6‐di‐O‐pentyl)‐cyclodextrin, octakis‐(2,3,6‐tri‐O‐pentyl)‐γ‐cyclodextrin, heptakis‐(3‐O‐trifluoroacetyl‐2,6‐di‐O‐pentyl)‐β ‐cyclodextrin, and heptakis‐(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin.Thermodynamic parameters (ΔG, ΔH, and ΔS) were determined from variable temperature measurements. The inclusion complexes containing styrene oxide were also studied by molecular modeling techniques. It has been found that a combined molecular mechanics–molecular dynamics approach may be a valuable tool for rationalizing the qualitative trends observed in the experimental separation factors. For the inclusion complexes considered here it is shown that the orientation of the gu

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150803

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

年代:1992

数据来源: WILEY

摘要:

AbstractA unified approach to sequential gas and supercritical fluid Chromatography using 50 μm i.d. open tubular columns is described. Sample introduction is performed by means of a rotary injection valve. In order that linear velocities can be optimized independently, a second rotary valve in the chromatographic oven is used to direct the flow of column eluate to the flame ionization detector through either fused silica tubing in GC, or a frit restrictor in SFC.Applications of sequential GC‐SFC on a 50 μm i.d. open tubular column are demonstrated, and comparisons made between sequential GC‐SFC on 50 and 100 μm i.d. c

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150804

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

年代:1992

数据来源: WILEY

摘要:

AbstractAs part of a study directed at introducing GMP recommendations to the production of non‐alcoholic beverages, combined Cl and El mass spectra have been used for the identification of compounds present in extracts of “Cockta” beverage following GC‐MS analysis. The amount of useful information present both in the separate Cl and El spectra, and in two of the possible combinations of the spectra, is de

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150805

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

年代:1992

数据来源: WILEY

摘要:

AbstractIt is possible to determine the animal of origin of dairy products and raw and cooked meats by high resolution capillary GC of fatty acid methyl esters. This is demonstrated by several examples.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150806

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

年代:1992

数据来源: WILEY

摘要:

AbstractRun‐to‐run sample separation reproducibility has been compared on two commercial high performance capillary electrophoresis units which differ in the mode by which the capillary temperature is thermostatted. Three standard analytes, differing dramatically in molecular character and size, were used for the analysis: benzoic acid, a 14 amino acid peptide from human chorionic gonadotropin, and ribonuclease A represent, respectively, small stable organic molecules, small peptides with little or no secondary structure, and proteins with secondary structure. These standards were evaluated with regard to reproducibility of migration time, peak area, and peak height. The analyses, performed in buffers of optimum pH for the separations, demonstrated that the liquid and forced air convection thermostatted systems both performed extremely well. The reproducibility, as judged by the percent coefficient of variance (%CV) of replicate analyses, was generally found to be less than 1 % (migration time); the reproducibility decreased in the order migration time>peak height>peak area. Whereas the absolute %CVvalues forMTrel(migration relative to a standard) observed with the liquid thermostatted system were 2‐ to 4‐fold lower than those observed with the forced air convection thermostatted system, there was little statistically significant difference between the two. As expected, the data indicated a reduction in reproducibility as the complexity of the analyte increased, perhaps as the result of an increased potential for wall interactions. Comparing separations in which low (≈︁1 watt/meter [W/m] of capillary) and high (>5 W/m) Joule heat was generated by altering the sodium chloride content of the buffer revealed few statistically significant differences in the reproducibility obtained from the two systems. With these particular standard analytes and their respective buffer systems, there appears to be little difference between forced air convection and liquid thermostatting of th

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150807

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

年代:1992

数据来源: WILEY

摘要:

AbstractEmissions from diesel engines contain mutagenic compounds, many of which are derivatives of polycyclic aromatic hydrocarbons. The complexity of extracts of particulate matter requires multi‐stage chromatographic analysis performed off‐line.In this study, coupled LC‐GC is presented as an alternative method for the analysis of the polar fraction of extracts of diesel particulate matter. Preseparation of the sample was achieved by normal phase HPLC and fractions were transferred to the GC through an on‐column interface. Through selective transfer, extensive characterization of the extract is possible and chromatograms can be greatly simplified, thus aiding identif

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150808

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

年代:1992

数据来源: WILEY

摘要:

AbstractA BASIC computer program for calculation of maximum plate number and minimum analysis time conditions for columns operated at various outlet pressures was presented in 1985 [1]. This sequel reports extensions to the program forn‐alkanes separated on polydimethylsiloxane stationary phases, specifically forn‐C2throughn‐C20on phases equivalent to SE‐30 or OV‐1. For these solute–phase systems the amount of thermodynamic data available is sufficient to enable calculation of several parameters.Firstly, the separation temperature is now automatically calculated for a requested capacity ratio, orvice versa. Secondly, the computation of solute diffusivities in the stationary phase has been improved to approach experimental data more realistically, particularly for highern‐alkanes at higher temperatures.The largest extension to the program is the inclusion of a facility enabling calculation of column sample capacity, minimum detectable amounts for FID and TCD detectors, and column working ranges. These parameters are again calculated forn‐alkanes, but are, of course, independent of the nature of the stationary phase. The updated program has been and is being used on a routine basis in our laboratory; it has been found to be reliable and has on numerous instances been prov

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150809

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

年代:1992

数据来源: WILEY

摘要:

AbstractLubricating oil additives have been analyzed by supercritical fluid chromatography on open tubular and packed capillary columns. Carbon dioxide and modified carbon dioxide were used as mobile phases and detection was accomplished by flame ionization and micro UV. Rapid and efficient analysis of the lubricating oil additives was demonstrated.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150810

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe matching of the pattern of peaks produced during gas chromatography is of importance to many applications. At present, this task is generally performed manually, but this generates the usual problems associated with human inspection, such as a lack of objectivity and reproducibility, proneness to errors, and practical restriction of the volume of data which can reasonably be processed.This paper explores the use of a novel algorithm for automation of this task. The performance of the method on well controlled simulated data sets and real chromatograms is used to show not only how problems of manual inspection can be circumvented, but also how the existence of such a powerful method should open up the possibility of many new analyses for quality control, discrimination of varieties of sample, and the identification of specific components within a sample.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150811

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

年代:1992

数据来源: WILEY