Phase cellulosics

The reagent can be used, for example, on silica gel, kieselguhr and Si 50000 layers as well as on RP, CN, NH2 and DIOL phases. Cellulose and polyamide 11 layers char on heating. 

Chiral separations have become of significant importance because the optical isomer of an active component can be considered an impurity. Optical isomers can have potentially different therapeutic or toxicological activities. The pharmaceutical literature is trying to address the issues pertaining to these compounds (155). Frequendy separations can be accomplished by glc, hplc, or ce. For example, separation of R(+) and S(—) pindolol was accomplished on a reversed-phase cellulose-based chiral column with fluorescence emission (156). The limits of detection were 1.2 ng/mL of R(+) and 4.3 ng/mL of 5/—) pindolol in serum, and 21 and 76 ng/mL in urine, respectively. 

Graham R.G., Bergougnou M.A., Free B.A. (1994) The Kinetics of Vapour-Phase Cellulose Fast Pyrolysis Reactions. Biomass and Bioenergy, 1, 33-47. 

The variables in o mean they are based on the whole control volume, in <> mean they are based on porous volume, in o mean they are based on volume occupied by the active cellulose. The whole control volume is occupied by solid phase (cellulose and char), liquid phase (active cellulose) and gas phase (porous volume). Considering the flow of gas and liquid through the porous cellulose, Darcy s law (Eqs... 

Broido, A. Kinetics of Solid Phase Cellulose Pyrolysis in Thermal Uses and Properties of Carbohydrates and Lignins , Shafizadeh, F. et al. (ed.), Academic Press, New York, 1976. 

The Whatman No. 1 paper (as received) contained 4.1 vol Z moisture and 0.074 wt Z ash. All results reported here are on a moisture- ash-free basis unless other wise specified. Table II summarizes some analytical results of cellulose and condensed-phase cellulose pyrolysis products. A comparison of the results In Table II for cellulose and cellulose tars Indicates that the elemental composition of these two materials Is very similar. (The heating... 

Liu, J. Stewart, J.T. High-performance liquid chromatographic analysis of ondansetron enantiomers in human serum using a reversed-phase cellulose-based chiral stationary phase and solid-phase extraction. J. Chromatogr. B Biomed. Sci. Appl. 1997, 694, 179-184. 

N aphthylethylurea Helical polymer phases Cellulose triacetate... 

This cellulose I (ie, natural cellulose) contains two coexisting phases cellulose la (triclinic) and cellulose Ip (monochnic) in varying proportions dependent on its origin (Horii et al., 1997). The relative proportion of these two different crystal structures varies depending on the source of the cellulose. In both aUomorphs, the molecules have very close to strict twofold screw symmetry along the chains praising two glucose units (Yamamoto and Horii, 1993). 

Gaudry and Ploux (1992) reviewed TLC studies on biotin and noted that this technique is more convenient and gives better results than paper chromatography in the analysis of this vitamin from multivitamin mixtures. They noted that although silica gel is generally used as the support phase, cellulose powder has also been proposed they provided tabular data on typical mobile phases used for the TLC analysis of biotin. 

Keywords Liquid crystalhne phases, cellulose-based polymer, nanocrystalline cellulose, microcrystalline cellulose, composites, films, electrospun fibers... 

Besides being at the origin of lyotropic phases, cellulose derivatives can also originate thermotropic liquid crystalline phases without solvent. This behavior is an indication that lateral chains act as solvent, or plasticizer, increasing the mobility of the polymer backbone. 

Figure 19.5 Illustration of phase inversion process involves transformation from a liquid phase cellulose solution to a solid state of the polymer.

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