Chromatographic descriptors

Retention factor (sometimes called capacity factor) is a very convenient chromatographic descriptor since it is dimensionless and independent on the... 

Efficiency and selectivity are complementary chromatographic descriptors. A column with high efficiency can generate narrow chromatographic zones and allows the separation of analytes with low selectivity. On the other hand, if the chromatographic system has high selectivity for two analytes, they could be separated on the column with low efficiency, as shown in Figure 1-9. 

In the following sections the chromatographic descriptors introduced above [equations (2-l)-(2-4)] will be discussed in terms of their functional dependencies, specifics, and relationships with different chromatographic and thermodynamic parameters. 

In Section 2.1 the main chromatographic descriptors generally used in routine HPLC work were briefly discussed. Retention factor and selectivity are the parameters related to the analyte interaction with the stationary phase and reflect the thermodynamic properties of chromatographic system. Retention factor is calculated using expression (2-1) from the analyte retention time or retention volume and the total volume of the Uquid in the column. Retention... 

Bate-Smith-Westall retention index chromatographic descriptors BC(DEF) coordinates BC(DEF) parameters BC(DEF) parameters f BC(DEF) coordinates)... 

Kovats retention index chromatographic descriptors Kuhn lengti) -> size descriptors... 

There are several methods developed for the calculation of logP from molecular structure, based on -> substituent constants, - fragmental constants, - electronic descriptors, -> steric descriptors, - connectivity indices, surface areas, - volume descriptors, and -> chromatographic descriptors [Leo, 1990 Hansch et al., 1995b Carrupt et al., 1997 Reinhard and Drefahl, 1999]. 

CHI index = chromatographic hydrophobicity index chromatographic descriptors... 

Migration Index —> chromatographic descriptors ( capacity factor)... 

PharmPrint descriptors substructure descriptors ( pharmacophore-based descriptors) phase capacity ratio = capacity factor —> chromatographic descriptors... 

They constitute the most important class of experimental measurements and play a fundamental role as —> molecular descriptors both for their availability as well as for their interpret-ability [Exner, 1966 Lyman, Reehl et al., 1982 Reid, Prausnitz et al, 1988 Horvath, 1992 Abraham, 1993c Baum, 1997 Lide, 1999 Reinhard and Drefahl, 1999]. Physico-chemical properties are used both as the molecular properties to be correlated with molecular structure in QSPR modeling and as the molecular descriptors when searching for relationships with biological activities. Physico-chemical properties are constitutive parts of volume descriptors, —> electric polarization descriptors, spectra descriptors, chromatographic descriptors, and so on. Combinations of physico-chemical properties are largely used in the definition of environmental indices. Other important physico-chemical properties are the so-called technological properties useful to characterize materials. 

Deconinck, E., Ates, H., Callebaut, N., van Gyseghem, E. and Vander Heyden, Y. (2007) Evaluation of chromatographic descriptors for the prediction of gastro-intestinal absorption of drugs. J. Chromat, 1138, 190-202. 

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