摘要:

AbstractMany solvent extracts must be concentrated prior to analysis. Both Kuderna‐Danish (K‐D) concentration and inert gas blowdown are commonly used. Significant losses often occur with the latter. Solvent removal/thermal desorption (SRTD) on a precolumn was investigated here as an alternative or supplement to these methods. The compounds studied included polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs). SRTD was carried out by injecting 100 μL of extract into a cartridge‐type precolumn, selectively volatilizing the solvent with a stream of carrier gas, then thermally desorbing the analytes to a fused silica capillary gas chromatography (GC) column. The mean total recoveries and mean standard errors obtained were 109 and ±12%, respectively. SRTD was found to give sharper peaks than were obtainable with on‐column injection. Method detection limits accessible for PCBs by capillary GC with electron impact mass spectrometry with the assistance of SRTD were estimated. Overall, SRTD was found to be an effective, rapid, high recovery concentration method for solvent

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100902

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

年代:1987

数据来源: WILEY

摘要:

AbstractTo understand the chromatographic process as a whole, whether it be for gas chromatography (GC), liquid chromatography (LC), or supercritical fluid chromatography (SFC), one needs to know the chemical and physical nature of the mobile and stationary phases and also the interactions that take place between analytes (solutes) and the two phases. An approach towards Investigating the ways that stationary and mobile phases contribute to chromatographic retention Involves exploring the effects of solvent polarity on the strength of the mobile phase. In SFC this could involve determining the polarity of several different modifier/carbon dioxide mobile phases. In this paper, the use of a solvatochromic indicator to learn more about the effects of SFC modifier/mobile phase polarity will be investigated and discussed using several different modifiers and a diolmodified silica column.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100903

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

年代:1987

数据来源: WILEY

摘要:

AbstractPreliminary results of a recycle system employing fused silica capillary columns are discussed. The unit, which can be operated with a pre‐column for multidimensional GC, utilizes continuous stream splitting for off‐line flame ionization detection. Commercially available rotary valves were used for recirculation of the chromatographic zone between column loops. Adsorptive activity, which is shown to be additive, is a serious limitation in the analysis of polar compounds. The successful application of recycle chromatography to increase resolution on non‐polar mixtures is demonst

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100904

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe retention of group 6 metal trifluorophosphine carbonyl compounds in serially‐coupled gas capillary columns has been studied as a function of different column configurations. For the trifluorophosphine‐substituted Mo, W, and Cr carbonyls, as well as the analogous Fe compounds, it was observed that the maximum resolution achievable by the coupled column technique was dependent on the order in which the nonpolar (DB‐1) and moderately polar (DB‐1701) columns were connected. The optimum configuration was different, however, for each series M(PF3)x(CO)6−x(M = Cr, Mo, or W) or Fe(PF3)x(CO)5−x. It was also observed that the use of coupled columns of dissimilar polarity can, in some cases, actually decrease resolution relative to that obtained by coupled identical columns (i. e. DB‐1 + DB‐1, or DB

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100905

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

年代:1987

数据来源: WILEY

摘要:

AbstractA simple micro‐method is described for determination of 15 organochlorine pesticide residues in mixed feeds. Clean‐up of the petroleum ether extract is by basic alumina minicolumn chromatography and quantitative identification is by capillary gas chromatography with electron capture detection. Cyanopropyl‐polysiloxane chemically bonded fused silica capillary columns have been used to perform high resolution analyses in short time as well as to overcome possible interferences by PCBs. Recovery, repeatability, and detection limits of the proposed procedure are checked and results are also reported for non random samples of 180 feeds collected in

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100906

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100907

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100908

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100909

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100910

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100911

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

年代:1987

数据来源: WILEY