Modified method for filling micro-HPLC-columns

This review discusses many different aspects of microcolumn liquid chromatography (LC) and reflects the areas of microcolumn LC research interest over the past decades. A brief theoretical discussion on a number of major issues, such as column characterisation, chromatographic dilution effects and extracolumn band broadening in microcolumn LC is given. Recent progress in column technology and the demands and developments of instrumentation and accessories for microcolumn LC are also reviewed. Besides that, the developments in a large number of established and also more recent detection techniques for microcolumn LC are also discussed. The potential of hyphenation of microcolumn LC with other techniques, more particularly of multidimensional chromatography and microcolumn LC coupled to mass spectrometry is reviewed. Finally, the perspective of microcolumn LC separation methods is stressed by a number of relevant applications.

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“…[76][77][78][79][80][81][82]), but also by column parameters (such as column blank material, frit selection, etc. [76,[83][84][85][86]).…”

Section: Column Developmentsmentioning

confidence: 99%

Microcolumn liquid chromatography: instrumentation, detection and applications

Vissers¹,

Claessens

Cramers

1997

Journal of Chromatography A

208

101

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“…Sampling of size-classified raindrops was performed by the "Guttalgor" (Latin: gutta -drop; algor -frost) method described in detail elsewhere [1]. Raindrops were sampled by freezing them in liquid nitrogen.…”

Section: Sampling Methods and Sitementioning

confidence: 99%

“…but for the investigation of microphysical processes this assumption is not true. B~ichmann et al [1][2] have found a dependence of the concentration of trace elements on the radius of raindrops ("c/r-dependence"). Different mechanisms are responsible for the variation in the chemical content of raindrops [3][4]: -evaporation -particle and gas scavenging -collision, coalescence and break up of raindrops -chemical reactions inside raindrops.…”

Section: Introductionmentioning

confidence: 99%

Development of new methods for the analysis of carboxylic acids and carbonyl compounds in size classified raindrops by CE for application in modelling atmospheric processes

et al. 1997

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Suhtmary ~At the present time the formation processes of clouds and precipitation are not totally understood. Because cloud-and raindroplets are major sinks for chemical species in the atmosphere it is important to understand the physical and the chemical processes which occur during precipitation. The development of models is hindered by the scarcity of information about the scavenging of gases or aerosol particles by raindrops of different sizes. These processes can only be investigated by field experiments using microanalytical methods and analysing single raindrops as well as size-classified raindrop samples. R~indrops were collected according to their size by freeflng them in liquid nitrogen ("Guttalgor" method). S~/mple volumes of the smallest raindrop sizes (radius < 200 gm) were usually smaller than 2 gL. The analysis of microvolumina in the size range of gL down to pL required the development of methods designed especially for this purpose. Analysis of rain samples was carried out by capillary electrophoresis. Organic acids were determined using a new electrolyte system for indirect detection. With this system it was possible to determine monocarboxylic acids (C1-C4) dicarboxylic acids (C2-C4, C9) and inorganic anions (CI-, NO3-, SO42-) in the rain samples. Carbonyl compounds were analysed after derivatisation with dansylhydrazine using direct UV-detection. The system allows the idenPresented at the 21 st ISC held in Stuttgart, Germany, 15th-20 th September, 1996 tification of aliphatic carbonyl compounds (C1-C3, C5) as well as benzaldehyd e. It was found that carbonyl compounds and carboxylic acids showed concentration maxima at different raindrop radii. These concentration maxima are a consequence of particle scavenging. By using the results of a former experiment we concluded that the two species are located on different aerosol particle sizes. Reasons for the different particle sizes where these species are located are discussed.

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