Comparing Stationary Phases on the Basis of LFER Data

1 Comparing Stationary Phases on the Basis of LFER Data 

The use of solute descriptors from the solvation equation (Eq. 5) for application in an LFER regression to characterize liquid chromatographic systems in terms of regression parameters is documented in numerous examples in the literature. To illustrate the procedure for determining these parameters and to demonstrate their convenience in phase characterization, an example from the literature, presented in a series of three publications [12-14], is discussed here. 

Multivariate linear regression can be carried out with common statistics software and was performed in the given example with Statistica 5.0 (StatSoft). Retention factors were measured for a set of selected test solutes using a set of different columns under one fixed set of eluting conditions (acetonitrile/water, 3 7, vjv, without addition of a buffer). A buffer was avoided, since Engelhardt and coworkers reported a marked modulation of column properties by salt or buffer additives this adulterates phase characterization and makes columns look less silanophilic than they actually are [15]. 

Stationary phase Manufacturer Ligand type Particle size (pm) Pore size (nm) Surface area %c approx. Abbre- viation 

The u parameter of the polymer-bonded PAH column is rather low considering its high bonding density. This can be explained by the increased pore diameter (15 nm) or the more rigid arrangement of the alkyl chains at the surface, which serve to enhance the so-called shape selectivity for PAHs this should also hamper cavity formation for hydrophobic solutes. 

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