ISSN:0935-6304    

DOI:10.1002/jhrc.1240090102

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe general topic of supercritical fluid chromatography (SFC) is introduced, and historical aspects of its development are discussed. The physical properties of supercritical fluids, gases and liquids are tabulated. SFC is compared and contrasted with the classical forms of chromatography ‐ gas chromatography (GC) and high performance liquid chromatography (HPLC). The selectivity of SFC, GC, and HPLC are discussed and compared. Instrumentation employed for supercritical fluid chromatography is depicted. A wide variety of SFC applications are introduced. New examples of the use of SFC for analysis of a variety of complex oligomeric mixtures indcluding polypropylene glycol, polysiloxanes, fluorocarbon oligomers (i.e.‐3M's fluoro‐chemical surfactant Fluorad 171, and Kel‐F) and high molecular weight normal alcohols are shown. The use of SFC for separation of mono‐, di‐, and triglycerides at low operating temperatures is described. Lastly, the use of SFC for separations of complex hydrocarbon mixtures from liquid fuels, polycyclic aromatic hydrocarbons, synthetic alpha‐olefins, and petroleum functional group separations

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090103

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effects of trapping temperature and column film thickness were investigated with respect to their ability to promote effective cryofocusing on fused silica capillary columns. The study was a further development of the purge and trap with whole column cryotrapping (P&T/WCC) method. The rates at which compounds could be thermally desorbed from a P&T unit and transferred to a column (with zero split) were first examined. A near quantitative transfer of the desorbable analytes was obtained with a 4 min, 180°C, 20 mL/min desorption. The compounds tested included naphthalene. Columns with film thicknesses from 0.12 to 3.0 μm were then investigated in P&T/WCC analyses with WCC temperatures ranging from −80 to 0°C. The trapping took place from a transfer line gas stream initially at 175°C. The volatilities of the compounds examined varied from that of 1,1‐dichloroethene to 1,1,2,2‐tetrachloroethane. A higher film thickness was found to ease the WCC temperature requirements. Within each column type, the warmest WCC temperatures which allowed good cryotrapping with no significant increases in peak width were: 0.25 μm, −70°C; 1.0 μm, −50°C; 3.0 μm, −20°C. In addition to being quantitative, the trapping provide

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090104

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

年代:1986

数据来源: WILEY

摘要:

AbstractElectroformed nickel tubing was deactivated by chemical vapor deposition of silicon from silane gas and subsequent treatment with cyclooctamethyltetrasiloxane (D4). Standard activity tests performed on the uncoated tube and also on columns coated with crosslinked and uncrosslinked, nonpolar stationary phase, show that good quality flexible columns can be prepared from nickel tubing. The inner surface of the silicon coated tube was characterized by Auger depth profile analysis.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090105

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

年代:1986

数据来源: WILEY

摘要:

AbstractNeutral steroid metabolites enriched from urine and hemofiltrate were identified by gas chromatography/mass spectrometry and quantified by capillary gas chromatography. This study included 20 healthy controls and 37 uremic patients. Before enrichment of steroids from biological material, the standard deviation of the workup procedure and subsequent derivatization into the trimethylsilyl‐enol‐trimethylsilyl ethers was tested and found to be 2–5% in urine and 12–17% in the more complicated workup procedure of hemofiltrate, but essentially smaller than the biological standard deviation. Compared to the 24 h urinary excretion rates of controls, the excretion rates of androsterone, etiocholanolone, and corticoid metabolites were significantly lower in uremic body fluids, while those of 11‐oxygenated androstanolones, degradation products of corticoids, were enhanced in uremic urine. The ratio of corticoid metabolites to 11‐oxygenated androstanolones in urine of nondialyzed uremics correlated significantly with their plasma creati

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090106

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

年代:1986

数据来源: WILEY

摘要:

AbstractDiesel fuels from different parts of the UK have been analyzed for polycyclic aromatic hydrocarbons (PAH), nitrogen‐containing PAH, and sulfur‐containing PAH using capillary column GC with simultaneous parallel triple detection. The concentrations of polyaromatic compounds (PAC) were high and showed considerable variability amongst the fuels. The PAH are mainly naphthalene, fluorene, and phenanthrene and their alkylated homologs; the PANH are mainly carbazole and its methyl derivatives; the PASH are mainly dibenzothiophene and its methyl derivati

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090107

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper demonstrates a novel operating mode of an ion mobility detector (IMD) for obtaining both qualitative and quantitative data after capillary gas chromatographic separation of 5,5′‐disubstituted barbiturates. Using a recently developed time dispersive Fourier transform method for ion mobility spectrometry, complete ion mobility spectra could be obtained for each component in the chromatogram. This type of spectra can be used for providing qualitative information on unknown compounds or for selecting the proper detector conditions needed when operating in the continuous mobility monitoring mode.In this study each of the five barbiturates investigated produced a Fourier transformed ion mobility spectrum containing one major product ion. When drift times corresponding to those of the product ions measured in the FT mode were monitored continuously, selective chromatographic detection of the barbiturates was achieved. In one case even isomers could be differentiated based on mobility characterist

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090108

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe preparation of wide bore (320 μm) and narrow bore (50 μm) fused silica capillary columns is described for immobilized cyanopropyl substituted silicones containing 60 and 88% substitution. The effect of high temperature deactivation with cyanopropylcyclosiloxanes was studied with a special test mixture. Curing was achieved with dicumyl peroxide or azo‐tert‐butane.The columns were evaluated and compared in terms of efficiency, activity, polarity, and temperature stability. Different coating methods were compared for the narrow bore columns. The activity of the 60% cyanopropyl columns that had been immobilized with dicumyl peroxide was significantly larger than for azo‐tert‐butane immobilized columns. The polarity of polar columns appeared to depend greatly on column temperature and is completely different for wide and narrow bor

ISSN:0935-6304    

DOI:10.1002/jhrc.1240090109

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.1240090110

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.1240090111

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

年代:1986

数据来源: WILEY