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Chromatographic scince series - Cazes J.

Cazes J. Chromatographic scince series - Marcel Dekker, 1996. - 1098 p.
ISBN 0-8247-9454-0
Download (direct link): ˝hromatography1996.pdf
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The unmodified stationary phases include silicas, aluminas, Kieselguhr, silicates, controlled-po-rosity glass, cellulose, starch, gypsum, polyamides, and chitin. For TLC and HPTLC the most
824
Szepesi and \
Table 2 Applicability of Capillary Action Planar Chromatography in Pharmaceutical Analysis (Data for Part 8 of Table 1)
Properties Advantage Disadvantage
Type of solute
Very polar Limited
Polar Good
Medium polar Good
Nonpolar Good
Structure of solute
Structurally different compounds Good
Isomers Good
Homologous compounds Limited
Size of solute
Small Good
Medium large Limited
Large Limited
Analytical task
Analysis of starting raw materials
Plant extracts Widely used
Extracts of animal organs Widely used
Fermentation mixture Widely used
Analysis of intermediates
Intermediates and crude Limited
products
Reaction mixtures Applicable
Mother liquors and secondary Applicable
products
Analysis of pharmaceutical raw
materials
Identification Generally used
Purity testing Alternative to HPLC
Assay Not applicable
Stability testing Complementary to HPLC
Analysis of formulated
products
Identification Generally used
Purity testing Alternative to HPLC
Assay Not applicable
Stability testing Complementary to HPLC
Content uniformity test Not applicable
Dissolution test Not applicable
Analysis of drugs and their meta Limited applicability
bolites in biological media
Pharmaceuticals and Drugs
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Selection of the stationary phase
...........1
Selection of the vapor phase
Selection of the suitable solvents
t "
Optimization of the mobile phase
tp -
Transfer of the optimized mobile phase to the adequate FFPC method
Selection of the development mode
Ž "
Selection of other operating parameters
Figure 1 Schematic of method development.
frequently used stationary phase is silica. It is prepared by spontaneous polymerization and dehydration of aqueous silicic acid, which is generated by adding acid to a solution of sodium silicate. The product of this process is an amorphous, porous solid, the specific surface area of which can vary over a wide range (200 to more than 1000 m2/g), as can the average pore diameter (10-1500 A) (32).
Modified silicas may be nonpolar or polar sorbents. The former class includes silicas bearing alkane chains or phenyl groups, while the polar modified silicas contain cyano, diol, amino, and thiol groups or substance-specific complexing ligands (34,35). The structures of some chemically modified silicas (36) are shown in Figure 2.
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