Impregnation layer

The dipping unit can also be employed to impregnate adsorbent layers. It is easy in this way to produce tungstate- [127] or silver nitrate-impregnated layers for separating oligosaccharides or unsaturated compounds. 

The reagent can be used, for example, on silica gel, kieselguhr and Si 50000 layers as well as on aluminium oxide, cellulose or chiral layers. Neither do difficulties occur on RP 18, Diol, NHj and CN phases. Silver nitrate- [4] and calcium oxalate-impregnated layers [9] are also suitable. However, polyamide phases are colored yellow. 

The higher the HCl concentration the thicker the impregnated layer of Pt becomes. 

Grassini-Strazza, G., V. Carunchio, and A. M. GireUi, Flat-bed chromatography on impregnated layers, J. Chromatogr. 466 1 (1989). 

Literature contains very few reports on ion pair chromatography upon impregnated layers. Schill et al. developed theoretically interesting systems 27-29), which allow the computation of the parameter governing ion pair chromatography. Such a system is described for the separation of certain tertiary and quaternary ammonium compounds8 . The system uses acetylated cellulose as support, 1-butanol or 1-pentanol as stationary phase and aqueous salt solutions in sulfuric acid as mobile phase. The salt solutions, which consist of NaCl or NaBr or NaC104 and sulfuric acid play the part of counter-ions. 

G. Impregnated layers Acid, alkaline, or buffered layers can be prepared with... 

Impregnation layer. [Data from Eichhloz, E1, Martinz D O, Solvin Paste PVC Handbook. 

The properties of composite materials cannot be predicted adequately by considering the fibre and resin constituents one by one. An important mechanism of composite failure under stress is delamination caused by differences between the engineering properties of successive plies or layers. These differences arise from the fact that successive layers may have different fibre orientations [34] or, occasionally, different fibres. It is a feature of laminates made by stacking pre-impregnated layers of reinforcement and is not an issue with, for example, unidirectional pultrusions. The process of delamination has been reviewed by Davies [35]. The fabrication of three-dimensional composites is an important step towards reducing or eliminating unwanted delaminations. Such materials are at an advanced stage of development. 

Obvionsly, if nsed for a separation and elntion is to be done, those impregnated layers with inorganic salts wonld generally not present a problem. However, those with some organic additives wonld reqnire special extraction or workup. No further details will be given but the reader can contact the manufacturers. 

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