ISSN:0935-6304    

DOI:10.1002/jhrc.1240110902

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe properties of hexakis(3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐α‐cyclodextrin as a chiral stationary phase for capillary gas chromatography are described. For the first time the enantiomers of a series of different lactones are separated and their order of elution is assigned. Moreover, the enantiomers of trifluoroacetylated aldols and amino alcohols, the cyclic carbonates of 1,2‐diols, 1,3‐diols,O‐alkylated glycerols, and some chiral pharmaceuticals are also separated on the new chiral phase. The modified α‐cyclodext

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110903

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

年代:1988

数据来源: WILEY

摘要:

AbstractPTV splitless injection cannot compete with on‐column injection as far as simplicity, reliability, and accuracy of quantitative analysis is concerned. However, PTV splitless injection is attractive for trace analysis of samples containing high concentrations of involatile sample by‐products. Maximum injection volumes are limited by the amount of liquid that can be retained within the PTV injector chamber and are around 20–30 μl injected at once. Solvent evaporation must be carried out in such a way that injector overflow is a

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110904

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

年代:1988

数据来源: WILEY

摘要:

AbstractSix isomeric C20alkylthiophenes were synthesized in order to prove the occurrence of such compounds in various deep sea sediments. As expected from the analogy with the corresponding saturated hydrocarbons, 2‐ and 3‐heptadecylthiophene have considerably longer relative retention times than the isomeric isoprenoid compounds,i.e.2‐ and 3‐(4,8,12‐trimethyltridecyl)thiophene and 3‐ and 4‐methyl‐2‐(3,7,11‐trimethyldodecyl)thiophene. Covats retention indices for all compounds were determined by isothermal analysis at 190°C on two different silicone‐coated capillary columns. The mass spectra of the monoalkylated thiophenes show a base peak at m/z 98 corresponding to a Mcafferty rearrangement product in the case of the 3‐substituted isomers, whereas a simple benzylic cleavage dominates in the mass spectra of 2‐alkylthiophenes. 4‐Methyl‐2‐(3,7,11‐trimethylodecy)thiophene is an exception from this simple rule because also shows the McLafferty rearrangement as dominant fragmentation. Two of the isoprenoid thiophenes are prominent compo

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110905

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

年代:1988

数据来源: WILEY

摘要:

AbstractElectrochemical (ECD), fluorescence (FLD), and UV spectrophotometric (UVD) detection were used to monitor various S‐alk(en)yl‐L‐cysteines and their corresponding sulfoxide isomers following pre‐column derivatization with o‐phthaldialdehyde‐tert‐butylthiol and separation by reversed‐phase HPLC. Recording of hydrodynamic voltammograms, FLD stop‐flow scanning, and on‐line captured UV spectra were methods used for establishing optimal detector settings which were defined as a compromise between favorable selectivity and high sensitivity. Optimal detector settings were found at: (A) 750 mVvs. Ag/AgCl for ECD; (B) excitation at 230 nm and emission at 420 nm for FLD; and (C) 337 nm for UVD. Various aspects of detector practicability such as selectivity, baseline disturbances due to excessive reagent, scanning possibilities, as well as detection limits were evaluated and compared. Minimal detectable amounts of the compounds were in the range of 130‐160 fmol for ECD, and 2.5‐3.5 pmol and 13‐16 pmol for FLD and UVD. In addition, the possibilities and benefits of detect

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110906

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110907

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110908

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110909

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110910

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110911

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

年代:1988

数据来源: WILEY