摘要:

AbstractA comparison is made between dichlorosilanes and cyclic siloxanes as starting materials in the synthesis of stationary phases for capillary gas chromatography (CGC) and supercritical fluid chromatography (SFC). Siloxanes containing one or more of the side groups methyl, vinyl, phenyl, and cyanoethyl in various ratios were synthesized and compared. These phases were characterized by chromatographic (gel permeation, GPC), spectroscopic (IR,1H NMR,29Si NMR), and thermal (DSC) methods. Coated fused silica columns were evaluated with respect to polarity, crosslinkability with several free‐radical initiators, and thermal stability. A new liquid phase, 7% cyanoethyl, 7% phenyl, 1% vinyl methyl polysiloxane is shown to be more polar than OV‐1701, more temperature stable, easily crosslinked and suitable for use in supercritical fluid chromatogra

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081202

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

年代:1985

数据来源: WILEY

摘要:

AbstractA two‐dimensional chromatographic separation is described which makes use of the unusual properties of supercritical carbon dioxide mobile phase. This solvent has the property of giving a separation of polycyclic aromatic hydrocarbons (PAH) on amine‐bonded columns similar to that given by usual normal‐phase solvents, and on octadecylsilane‐bonded columns similar to that given by usual reversed‐phase solvents.Packed columns were used, arranged so that they could be switched in or out of the solvent flow. Polycyclic aromatic hydrocarbon mixtures isolated from coal tar were fractionated according to number of aromatic carbon atoms on an amine‐bonded column, and these fractions were trapped on an octadecysilane‐bonded column. They were subsequently eluted according to the polarity of the individual compounds. Separations from fractions containing 16 and 18 aromatic carbon at

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081203

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

年代:1985

数据来源: WILEY

摘要:

AbstractRadicals generated in linoleic acid and deuterated linoleic acid have been trapped by the spin trap 2‐methyl‐2‐nitroso‐propane (MNP) and identified by electron spin resonance (ESR) and ENDOR spectroscopy. The formation of two distinct secondary alkyl radical adducts (one conjugated, the other non‐conjugated, as shown by their UV absorption spectra) was demonstrated by 11, 11‐dideuterio‐9‐cis‐12‐cis‐linoleic acid using HPLC

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081204

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

年代:1985

数据来源: WILEY

摘要:

AbstractWork‐up procedures and HPLC separation systems for determination of taurocholic, glycocholic, chenodeoxycholic, and cholic acids and lysolecithin in artificial and natural gastric juice are described. These compounds are used for testing the binding capacity of antacida to the individual analytes. Work‐up is simple, no extraction or filtration being required. The optimized combinations of stationary and mobile phases allow selective and sensitive determination of the respective bile acids in gastric juice. For optimization, the capacity factors of two related bile acids were evaluated for numerous commercial stationary phases. The mechanism of retention is different for free and conjugated bile acids. Special aspects of routine analysis are discus

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081205

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

年代:1985

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081206

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe technique of spontaneous coating of capillary columns employing liquefied butane and ethylene chloride as solvents of the stationary phase is described. These solvents and their mixtures are suitable for apolar and medium‐polar stationary phases. The dependence of coating time on coating temperature and on the composition of the mixture of solvents was observed. It was found that the coating efficiency decreases with increasing coating spee

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081207

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

年代:1985

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081208

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

年代:1985

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081209

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

年代:1985

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081210

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

年代:1985

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240081211

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

年代:1985

数据来源: WILEY