摘要:

AbstractIn this work the combination of high‐speed narrow‐bore capillary GC with electron capture detection is evaluated. The make‐up gas flow rate is a key parameter in the successful coupling of narrowbore columns and ECD detection. The make‐up flow has to be as high as possible to eliminate peak tailing caused by the large detection cell volume. The sensitivities at these elevated make‐up flow rates (400 to 1000 ml/min), measured for some pesticides like HCB and dieldrin, were very good. Detection limits for these compounds of 0.1 pg were obtained, resulting in minimum detectable concentrations of approximately 0.2 ppb. The performance of the system is illustrated by several high‐speed analyses of environmentally relevant samples of PCBs and

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180702

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper deals with the separation of alkanes, naphthenes, and aromatic compounds in naphtha and reformate, on a newly developed apolar high resolution GC column. The selectivity of this apolar phase has been compared with those of squalane, DB‐1, and SE‐30. A total of 95 hydrocarbons were reliably identified, mostly by GC‐MS. Repeated measurements of Kováts retention indices are presented as evidence for the reproducible manufacture of fused silica columns coated with this

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180703

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe fatty acids of the total lipids, triglycerides, and the cyanolipid ofPaullinia elegans(Sapindaceae) have been analyzed as their methyl esters and 4,4‐dimethyloxazoline derivatives by gas chromatography‐mass spectrometry. It was shown that the gas chromatographic separation of the oxazoline derivatives was sufficient to ensure the correct identification of the monoenic fatty acid positional isomers. Stereochemistry of the double bonds has been confirmed by infrared and13C‐nuclear magnetic resonance (NMR) spectroscopy.cis‐13‐Eicosenoic Acid (Paullinic acid) (44.4%) andcis‐11‐octadecenoic acid (cis‐vaccenic acid) (19.8%) were found to be the main components beside other monoenoic acid positional isomers. The cyanolipid ofP. eleganswas identified as 2,4‐dihydroxy‐3‐methylenebutyronitrile derivative by IR,1H‐NMR,13C‐NMR spectroscopy and was quantified by1H

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180704

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe microwave energy produced by a high intensity microwave oven was used to extract polychlorinated biphenyls (PCB) from water samples. This static method was compared with liquid‐liquid extraction to determine the optimum and limiting conditions in extraction processes. The sample size and sample container shape determine the temperature profiles in the sample. Using a 500 mL sample size, the detection limit is in the low ng/L range when an electron capture detector is employe

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180705

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

年代:1995

数据来源: WILEY

摘要:

AbstractA capillary GC method employing an internal standard has been developed and successfully used for quantitative determination both of the raw materials used for the manufacture ofm‐phenoxybenzaldehyde and for the components of the reaction mixtures obtained at various stages of the development of the process. A complete analysis can be performed in a single temperature programmed ru

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180706

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

年代:1995

数据来源: WILEY

摘要:

AbstractChromatographic methods currently used for isolation, separation, and identification of the components of crude tall‐oil have been reviewed, and their resolution and analytical methodology compared. Sample introduction by cold on‐column, rather than vaporizing, injection provides good reproducibility and operational convenience for capillary GC analysis. Size exclusion chromatography for isolation followed by capillary GC‐MS for identification, gave the best performance for analysis of acidic and dimeric comp

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180707

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

年代:1995

数据来源: WILEY

摘要:

AbstractAn on‐line reversed‐phase LC‐GC method involving the use of a Programmed Temperature Vaporizer (PTV) as interface is used for the rapid analysis of sterols. The experimental procedure requires only the use of commercial HPLC and GC equipments and a Rheodyne valve. The LC preseparation can be performed satisfactorily even with aqueous eluents containing up to 25% water. Factorial experimental design is applied to investigate the sensitivity achievable in the analysis with some variables (adsorbent material used in the PTV, particle size and plug length) being considered at two different levels. As a result, the sensitivty can be increased by a factor as large as 35 merely by performing the analysis under the experimental conditions giving the highest response. The use of the proposed configuration allows the transfer of up to 1050 μL from LC into the GC system, 1400 μL/min being the speed of sample introduction. The proposed procedure was succesfully applied to the analysis of real

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180708

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

年代:1995

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180709

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

年代:1995

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180710

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

年代:1995

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180711

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

年代:1995

数据来源: WILEY