ISSN:0935-6304    

DOI:10.1002/jhrc.1240121102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe use of multidimensional gas chromatography (MDGC) for the analysis of essential oils is gaining in importance. A rarely used application consists in the enrichment of minor components through a MDGC system provided with a cold trap between trap column and analytical column. Under suitable conditions, in fact, the cold‐trap can store a trapped compound (or a fraction) for a long time. Consequently, the same fraction can be heart‐cut from several successive chromatographic runs on the first column and stored together in order to accumulate trace compounds; afterwards the accumulated fraction can be injected in the analytical column. The possibilities of this technique will illustrated through some examples of analysis of complex essential o

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121103

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

年代:1989

数据来源: WILEY

摘要:

AbstractA procedure has been developed for the automated determination of aflatoxin M1 in decreamed milk, by using on‐line dialysis and subsequent trace enrichment on a reverse phase column. After foreflush to the analytical column the determination is performed with fluorescence detection. Fully automated analysis within 10 min is thus possible with reproducible dialysis recoveries above 50% (CVis 3.3%,n= 20) and detection levels of 50 ng/k

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121104

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

年代:1989

数据来源: WILEY

摘要:

AbstractSupercritical fluid extraction can be coupled with capillary gas chromatography (SFE‐GC) using commercially‐available on‐column or split/splitless injection ports. While liquid solvent extractions require several hours or even days to perform, SFC‐GC analyses can be completed in ≤ 1 hour including extraction, analyte concentration, and GC separation. SFE‐GC yields chromatographic peak shapes that compare favorably with those obtained using conventional liquid solvent injections. Quantitative extraction and recovery of analytes is usually achieved in 10 minutes, and maximum sensitivity is obtained since the extracted analytes can be quantitatively transferred into the GC column for cryogenic focusing prior to GC analysis. SFE‐GC analysis of a variety of organic pollutants from environmental solids and sorbent resins, and flavor and fragrance compounds from food products will

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121105

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

年代:1989

数据来源: WILEY

摘要:

AbstractPartially concurrent eluent evaporation presupposes an eluent evaporation rate in the GC pre‐column that approaches the LC flow rate. Discharging the vapors through the whole GC column, evaporation rates reach 10–30 μl/min,i.e.are suitable just for LC flow rates typical for packed capillary LC columns. With an early vapor exit, evaporation rates are increased to 100–200 μl/min (under extreme conditions to some 800 μl/min), thus fitting the LC flow rates of 2 mm i.d. columns.Evaporation rates were measured for a standard set of pre‐columns and conditions. The dependence of the evaporation rate on temperature, inlet pressure, carrier gas, and internal diameter of the retaining pre‐column are discussed in order to allow the design of a GC system producing a desired evap

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121106

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

年代:1989

数据来源: WILEY

摘要:

AbstractA novel dynamic headspace gas chromatographic system equipped with a wide bore capillary column was constructed for direct analysis of less volatile components in polymeric materials such as coating paints. With this system, the determination of typical paint additives such as hindered amine light stabilizers and ultraviolet absorbers could be carried out within a short time.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121107

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

年代:1989

数据来源: WILEY

摘要:

Abstractγ‐Cyclodextrin with 3‐O‐butyryl and 2,6‐di‐O‐pentyl residues is a very versatile chiral stationary phase for enantiomer separation. Most of the common and many uncommon amino acids can be separated as well as α‐ and β‐hydroxy acids, chiral alcohols, diols, triols, ketones, bicyclic, and tricyclic acetals, amines, alkyl halides, lactones, and functionalized cyclop

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121108

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to modify an automatic pre‐concentration system to avoid water contamination and to apply this technique to ethane analysis in breath. The ion trap detector was very useful in monitoring the whole analytical procedur

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121109

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to accommodate continually changing tasks in the [μl/l]–[nl/m3] ranges of gas chromatographic trace analysis of gas phases and vapor phases, a simple and time‐saving calibration technique is presented which renders unnecessary conventional test mixtures of the abovementioned concentration ranges.This new method is based on the simulation of such mixtures at the inlet of the GC unit with the aid of commercially available multiway sampling valves of various volumes by means of partial pressure samp

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121110

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

年代:1989

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240121111

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

年代:1989

数据来源: WILEY