摘要:

AbstractA simple but effective GC approach to odour evaluation and fraction collection with capillary columns is described. An allglass device splits the column effluent, with one splitter arm going to an FID. For odour evaluation, the other splitter arm is led via teflon tubing to the nose. Off‐line heart‐cutting is carried out by collecting the split effluent on a glass capillary microtrap, the inner walls of which are coated with OV‐101. This allows recovery of nanogram amounts of material. Multipass operation or repeated collection leads to preparative capillary GC for further spectroscopic investigation. These techniques do not involve sophisticated equipment or valves. Applications of this type of smell analysis, heart‐cutting and enrichment in the analysis of Rhododendron fragrantissimum essential oil, black pepper essential oil and hop essential oil, illustrating the versatility of the systems, are pr

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030302

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

年代:1980

数据来源: WILEY

摘要:

AbstractA new surface pretreatment for the preparation of wall‐coated open tubular (WCOT) glass capillary columns has been evaluated. This technique involves the application of a non‐extractable layer of Superox™‐4, a 4,000,000 MW polyethylene glycol, to the glass surface as a pretreatment and deactivation agent. Unlike other polyethylene glycols, Superox‐4 is stable at high temperatures (>300°C) in the absence of oxygen, coats smoothly onto a bare glass surface and resists droplet formation. WCOT columns (SE‐54, Carbowax 20M, and SP‐2250) prepared using this technique are compared to columns prepared using a modifiedGrob[2,3] BaCO3procedure. The Superox‐4 pretreated columns were equal or superior in quality to the BaCO3pretreated columns, based on the appearance of an activity standard and the effective theoretical plates (Neff) per meter. Chromatograms showing practical application of the WCOT columns prepared using both

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030303

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

年代:1980

数据来源: WILEY

摘要:

AbstractBasic expressions are derived for both the retention time and the effective separation factor in serially coupled GC columns. The retention time is determined by two main parameters. The first is the fractional time spent by an unretarded solute in each column which, in turn, is determined by the relative column lengths and flow velocities through each column. The second parameter is the relative mass distribution coefficient of a particular solute in each column; a variable that can be adjusted by changing the relative temperatures of the columns. The expression for the effective separation factor relates the measured separation factor for the series combination to the separation factors on the individual columns, the fractional time spent by an unretarded peak in each column, as well as the relative values of the mass distribution coefficients of a particular solute on the different columns.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030304

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

年代:1980

数据来源: WILEY

摘要:

Abstract1‐(o‐methoxyphenoxy)‐3‐isopropylamino‐2‐propanol hydrochloride (moprolol, OmeralR), is a new β‐adrenergic blocking agent. A gas chromatographic method for determining unchanged moprolol in human biological fluids has been developed. After solvent extraction, a bis‐trifluoroacetyl derivative was formed and measured by an electron capture detector. The quantification was checked by using an internal standard (pronethalol), which was added to all samples. The electron capture response was linear between 10 and 500 ng/ml. To avoid contamination of the peaks, careful extraction was imperative. The main advantages offered by the described method are: specificity, high sensitivity (10 ng.ml−1) and the small amount of biological fluids (1 ml plas

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030305

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

年代:1980

数据来源: WILEY

摘要:

AbstractSeveral impurities which were suspected to be present in commercial reagent‐grade phenol were separated using high performance liquid chromatography following sample concentration by steam distillation. A reverse‐phase, microparticulate column and 5 solvent systems containing 5% to 25% methanol in 0.05Mphosphoric acid were used. A variable wavelength ultraviolet detector and an electrochemical detector were connected in series, in that order, to the column. Capacity factors (ḱ) for pyrogallol, hydroquinone, resorcinol, catechol, orcinol and phenol were determined in the 5 solvent systems and compared to ḱ‐values of impurities present in the residue remaining from the steam distillation of phenol. Co‐chromatography of standards suspected as contaminants and possessing ḱ‐values similar to those of impurities were carried out in 3 solvent systems to confirm identical retention characteristics. Detector response ratios of contaminants and suspected standards, using various wavelengths and voltage potential settings, were utilized as major identification parameters. Two of the several contaminants separated were identified as hydroquino

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030306

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

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030307

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

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030308

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

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030309

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

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper describes a design for an all‐glass GC/MS interface. The design has advantages due to low dead volume, lack of column effluent adsorption and degradation, simple interface production and installation, and ease of column mounting/dismountin

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030310

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

年代:1980

数据来源: WILEY

摘要:

AbstractA direct densitometric method for the quantitative measurement of reserpine and ajmaline in whole roots and bark of roots ofRauwolfia Vomitoria, after extraction and separation by thin‐layer chromatography, is described. The emission and excitation spectra of the reserpine and the absorption spectrum of the ajmaline were scanned. The linear range between peak area and concentration is give

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030311

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

年代:1980

数据来源: WILEY