摘要:

AbstractCapillary GC was invented a long time ago – in this respect it is aging – but its potential is still far from being fully exploited and it is still an excellent playground for analysts looking for rewarding subjects. The author laments that there is not more activity in the field, provides some tips and subjects for anyone wishing to make his profession more colorful, and does not agree with managers who believe that “lean analysis”, i.e. execution of recipes without any experimenting with the technique, is cost‐effective. Good analysts somewhat resemble artists in character, but can be highly profitable for a laboratory, provided they are given the background to be

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160602

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

年代:1993

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160603

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

年代:1993

数据来源: WILEY

摘要:

AbstractA new multichannel autosampler which can automatically analyze up to twenty samples in sequence has been developed forCuriepoint pyrolysis – capillary GC. Compared with a previous system [1] the transfer line between the pyroysis unit and chromatograph is shorter, and thus has less dead volume, and can be operated at a higher temperature (300 °C). The relative yields of higher boiling point, highly polar, and thermally labile pyrolysates generated from polymers, and the reproducibility, were better than those obtained from the previous autosampler. To facilitate rapid operation an additional flow controller is installed on the new device to shorten the time taken to purge air from the sampl

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160604

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

年代:1993

数据来源: WILEY

摘要:

AbstractSupercritical carbon dioxide can be utilized both as an introduction solvent in capillary SFC and as a reaction medium; both possibilities are illustrated in this study. An off‐line SFE unit was modified for on‐line SFE‐SFC. To facilitate rapid depressurization of the extraction cell and to prevent memory effects, a 6‐port valve was installed at the outlet line of the extraction unit. An increased background signal was obtained when PEEK polymer was used in the construction of the extraction vessel; when stainless steel was used, the blanks improved. The synthesis of methyl esters and butyl esters of fatty acids from triglycerides in edible fat was examined using an immobilized lipase as a catalyst in on‐line SFE‐SFC. As a result of 30 minutes reaction – extraction time, high yields of fatty acid esters were obtained at a pressure of 150 bar and a temper

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160605

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

年代:1993

数据来源: WILEY

摘要:

AbstractAmylopectin tris(phenylcarbamate) has been evaluated as a chiral stationary phase for HPLC; the influence on its cptical resolving capabilities of mobile phase composition and nature of the alcohol used as modifier has been studied. Separation and resolution of twelve arylalcohol racemates were examined. In most instances, the stationary phase exhibited high optical resolving capacity.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160606

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

年代:1993

数据来源: WILEY

摘要:

AbstractFor many applications using supercritical fluid extraction (SFE), modifiers may be required.This paper will present some findings regarding the use of various modifiers including methanol, hexane, acetone, chloroform, dichloromethane, toluene, and tributylphosphate, in on‐line and off‐line SFE with cryogenic adsorbent trapping. The specific applications involved the extractions of petroleum hydrocarbons and pesticides from naturally incurred so

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160607

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe separation of the geometric isomers of chromium and rhodium chelates of trifluoroacetylacetone and thenoyltrifluor‐oacetone was investigated using packed column supercritical fluid chromatography. Mobile phases consisting of neat and alcohol‐modified carbon dioxide were used, and the most favorable isomeric resolution was obtained with a phenyl stationary phase. The chromatographic performance was better for chelates with trifluoroacetylacetone than for the corresponding chelates with thenoyltrifluoroacetone. Chromatographic peak area analysis of the metal chelates investigated showed appropriate isomeric concentrations in the final diastereomeric products resulting from the synthetic procedu

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160608

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

年代:1993

数据来源: WILEY

摘要:

AbstractSelectively alkylated cyclodextrins have been used to resolve the enantiomers of 2,2′ alkylated biphenyls. The configurational stability of 2,2′‐dimethyl and 2,2′‐diethyl biphenyls is insufficient for gas chromatographic separation even at ambient temperature. 2‐Isopropyl‐2′‐t‐butyl‐ and 2,2′‐di‐t‐butylbiphenyl are configurationally stable under the conditions applied, whereas 2,2′‐diisopropyl‐ and 2,2′‐bis(trifluoromethyl)biphenyl show temperature‐dependent interconversion of the enantiomers during chromatography. The gas chromatographic separation of the enantiomers of someorthotrichlorinated biphenyls carrying 4, 5, and 6 chlorine substituents

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160609

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

年代:1993

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160610

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

年代:1993

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160611

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

年代:1993

数据来源: WILEY