Chromatography self-supporting

Catalytic combustion experiments have been performed in a flow reactor operating below the lower explosion limits using HC/02/He mixtures. The product analysis was done by gas chromatography. FT-IR spectra have been recorded with a Nicolet Magna 750 instrument, using conventional IR cells connected with evacuation-gas manipulation apparatus. The powder was pressed into self-supporting disks, calcined in air at 773 K and outgassed at 773 K for 20 minutes before experiments. 

Planar chromatographic methods include thin-layer chromatography (TLC) and paper chromatography (PC). Each makes use of a flat, relatively thin layer of material that is either self-supporting or is coated on a glass, plastic, or metal surface. The mobile phase moves through the stationary phase by capillary action, sometimes assisted by gravity or an electrical potential. 

In addition to cellulose papers, modified-cellulose papers and glass-papers are also used for specific purposes. It is difficult to decide whether some self-supporting layers such as micropore membrane filter sheets or powders held in glass-paper sheets should be included among papers or thin layers. Paper chromatography is carried out in a descendant, ascendent or radial (circular) fashion. The diversity of the technique and the innumerable purposes to which it can be applied are discussed fully by textbooks and bibliographies, to which the reader is referred. 

Recently, self-assembly has been increasingly finding applications in fuel cells, solid-state battery electrolytes and plasticizers, chemical sensors, photovoltaics, bone implants, membranes, chromatography supports, and chemical delivery systems." " ... 

Another procedure for dealing with samples insoluble in counting solution is to support them on a medium such as paper strips, filter discs, glass fibre or DEAE cellulose prior to adding them to a counting vial [235-237]. As indicated earlier, use of this has been in chromatography where the spot has been cut out of the paper or scraped from the plate. Although useful for materials insoluble in scintillator fluid, self-absorption for tritiated samples may constitute a major drawback in this technique, just as it does for the suspension methods. It should be evident why the recent developments in in combustion procedures are so important in the problem of sample preparation. 

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