摘要:

AbstractThe addition of 1–20% (v/v) of methanol or acetonitrile as organic modifier to the mobile phase in a micellar electrokinetic capillary chromatographic (MECC) system, containing sodium dodecyl sulfate and a buffer, is shown to extend the elution range and thus increase the peak capacity of a given system. Although the net change in the elution range parameter, to/tmc, is essentially the same for both modifiers, the acetonitrile‐modified system exhibits much faster elution times for the polar and non‐polar test solutes employed in this study. Retention, as measured by the capacity factor, is generally decreased with the increase of an organic modifier, just as in conventional reversed phase chromatography. However, changes in selectivity as a function of the added modifiers are noted among polar and non‐polar solutes as well. The efficiency of these MECC systems is increased with the addition of either organic m

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110802

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

年代:1988

数据来源: WILEY

摘要:

AbstractCo‐solvent effects are applied to allow use of concurrent solvent evaporation for applications requiring analysis of compounds eluted less than some 50° above the column temperature during sample introduction,i.e.at oven temperatures below some 100–120°C. Required conditions such as GC even temperature, concentration of the co‐solvent and length of the uncoated pre‐column (retention gap) are studied theoretically as well as experimentally for the case ofn‐heptane as co‐solven

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110803

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe chromatographic separation properties of long, thin adsorption tubes enable substance‐specific quantitative enrichment and reduction to be achieved when sampling and thermal desorption are carried out in the same flow direction.The specific retention volumes, and also the breakthrough and peak end volumes, of 69 compounds in the boiling range between‐164 and 126°C and of a relative molecular mass between 16 and 119 were determined at temperatures between 30 and 130°C: normal alkanes, isoalkanes, cycloalkanes, alkenes, polyenes, alkynes, aromatics, ethers, alcohols, aldehydes, ketones, carboxylic acids and their esters, nitroalkanes, O‐heterocycles, S‐heterocycles, chloroalkanes, water, nitrogen monoxide, nitrogen dioxide, carbon dioxide, and sulfur dioxide.The correlation between adsorbent temperature and specific retention volume of these components, presented in the form of diagrams, permits the required quantity of adsorbent to be determined for a given sample volume. Contrary to literature sources, even extremely volatile compounds such as propane, propene, methanol, formaldehyde, formic acid, and chloromethane can be quantitatively retained on Tenax provided the operating conditions are appropriately

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110804

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

年代:1988

数据来源: WILEY

摘要:

AbstractPacked columns using 10 μm HPLC‐packing materials as supports for various liquid phases have been studied. The glass columns used were 80 mm long (o.d. 3 mm and i.d. 1.5 mm), the amount of solid support in the column being approximately 0.15 g. A. wide variety of separation characteristics were obtained by combining support material of various surface areas, chemically bonded surfaces, applied liquid phases, and various liquid phase loadings. This type of column is also characterized by a very short gas hold‐up time, leading to possibilities for relatively fast separations. Other advantages are high sample loading, high sample capacity, and low operating

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110805

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110806

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110807

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110808

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110809

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110810

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110811

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

年代:1988

数据来源: WILEY