ISSN:0935-6304    

DOI:10.1002/jhrc.1240110102

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.1240110103

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

年代:1988

数据来源: WILEY

摘要:

AbstractA method is described for the determination of 22 tetrachlorodibenzo‐p‐dioxin isomers at the low part‐per‐trillion (ppt) level. High resolution, narrow bore, open tubular columns (OTCs) with 100 μm i.d. can achieve better separations than presently used 320 or 250 μm i.d. columns in about half the total time. Relative retention times and response factors for all 22 TCDD isomers are presented for the electron capture detection and for the molecular ion mass of individual isomers under electron impact ionization with selected ion monitor

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110104

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

年代:1988

数据来源: WILEY

摘要:

AbstractReaction of amino acids withN‐methyl‐N‐(tert‐butyldimethylsilyl)trifluoroaceamide (MTbSTFA) in acetonitrile affords good yields of amino acid derivatives with excellent gas chromatographic and mass spectrometric properties. The single‐step derivatization procedure is highly reproducible. The TBDMS amino acids are stable at room temperature for at least three days. Only a single peak is observed for each amino acid. The procedure allows simultaneous analysis of asparagine and glutamine together with other serum amino acids. Separation is achieved on a borosilicate glass capillary coated with OV‐1. The mass spectra of the TBDMS amino acids possess characteristic diagnostic ions. These properties were used in the sensitive detection by GC‐MS and SIM‐GC‐MS of GABA and pipecolic acid in the serum of a newborn suspected of a Zellweger‐type syndrome, which could not be detect

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110105

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

年代:1988

数据来源: WILEY

摘要:

AbstractA splitless injection technique, allowing 0.5 μl injections on 50 μm i.d. columns, has been develope

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110106

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

年代:1988

数据来源: WILEY

摘要:

AbstractA method for the determination of individual free and conjugated bile acids in serum using microcolumn liquid chromatography coupled with a laser‐induced fluorescence detector is described. Bile acids are separated into free/glycine‐conjugate and taurine‐conjugate fractions using a Sep‐Pak SIL cartridge. The taurine‐conjugated bile acid fraction is subjected to enzymatic hydrolysis. Subsequently, free and conjugated bile acids are labeled using 4‐(bromomethyl)‐7‐methoxycoumarin as a fluorogenic reagent, producing stable derivatives that can be excited by the 325 nm line of a He/Cd laser. Prior to their fluorimetric detection, the individual components of a bile acid serum profile are separated by reversed‐phase microcolumn liqu

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110107

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

年代:1988

数据来源: WILEY

摘要:

AbstractStudies of mixed mobile phases in supercritical fluid chromatography must include consideration of a number of factors. Phase equilibria and critical parameters of a mixed fluid are very important in both the solvent delivery system and in the chromatographic column. The effects of pressure and temperature on retention with mixed mobile phases were studied and compared to estimated density values. System equilibration times with regard to pressure, temperature, and composition were studied. A mixed mobile phase was applied to the analysis of a high‐molecular‐weight metalloporphy

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110108

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

年代:1988

数据来源: WILEY

摘要:

AbstractAn analysis of the precision obtained using commercially available microvalve injectors is reported for three modes of injection: conventional split; timed‐split; and direct. Results from this study show that good precision (<3% RSD for external standard and<1% RSD for internal standard methods) can be obtained with capillary supercritical fluid chromatography (SFC). However, particular attention must be paid to the type of valve used, the orientation of the column relative to the valve, the mode of interfacing or connecting the column to the valve, and the type of pressure or density programming used for the analysis as all of these factors will affect the reproducibilit

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110109

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe retention behavior of condensed large polycyclic aromatic hydrocarbons has been investigated with diphenylsilica stationary phases in reversed‐phase microcolumn liquid chromatography. The results were correlated with two parameters which indicate size and shape of the molecules. Since the resulting equation can be used for retention prediction of large polycyclic aromatic hydrocarbons, computer‐assisted “standardless” identification is accomplished for “unknown” compounds contained in t

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110110

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe application of fluid extraction in combination with fluid chromatography with packed column and flame ionization detection is described. Fluid chromatographic equipment is shown. Applications of this system to drug characterization are demonstrated.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110111

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

年代:1988

数据来源: WILEY