Dolan-Snyder approach

In the LSER theory, two enantiomers have identical sets of descriptors, which correctly indicate that enantiomers are not separated by any isotropic stationary phase. They can, however, be separated by a CSP. This allows the relative Dolan-Snyder approach with a reference solute to be used for this special case [46]. In chiral separations, the reference solute will not be ethylbenzene, as recommended by Snyder, but it will be the less retained enantiomer of the enantiomeric pair. It is considered that one enantiomer sees a different CSP domain than the other enantiomer. Both enantiomers form two different transient diastereoisomeric complexes... 

In 1996, Snyder and Dolan elaborated the linear solvent strength (LSS) approach allowing the evaluation of log few from a single gradient run and its precise determination from two gradient runs [48]. From a practical point of view, LSS is the most useful approach to describe theoretical aspects and LSS gradients are convenient for optimization studies. Several commercially available optimization software packages which are able to predict resolution or retention in RPLC are currently based on this approach. 

Lewis, J. A., Snyder, L. R., and Dolan, J. W., Initial experiments in high-performance liquid chromatographic method development. II. Recommended approach and conditions for isocratic separation, ]. Chromatogr. A, 721,15,1996. 

Theoretical backgrounds of the determination of log Aw by gradient elution HPLC were elaborated recently by Snyder and Dolan [24]. The approach has been developed to determine both log Aw and p/f , of analytes by means of two gradient runs [25]. 

Gant, J.R. Dolan, J.W. Snyder, L.R. Systematic approach to optimizing resolution in reversed-phase liquid chromatography, with emphasis on the role of temperature. J. Chromatogr. 1979, 185, 153. 

Dolan, J.W. and Snyder, J.J. (1989) Troubleshooting LC Systems A Comprehensive Approach to Troubleshooting LC Equipment and Separations, Humana Press Totowa. New Jersey. 

In this section, a more recently published variant of a quantitative relationship akin to an LFER, but without the use of given solute descriptors and based on modified system parameters, is introduced [16]. All calculated data are derived solely from H PLC measurements, which constitutes the most important difference compared to the use of the solvation equation (Eq. 5). With this method, no a priori assumptions on the role of a certain parameter and its relation to a specific retention mechanism are made. The assignment to chromatographic principles is developed in the framework of the interpretation of each determined parameter, considering the chemical properties of the contributing test analytes. It should be mentioned that the senior authors of the relevant publications, John Dolan and Uoyd Snyder, have also contributed the following chapter to this book (Chapter 2.1.6), in which the application of their strategy to a wide variety of columns is presented. In this chapter, the applied procedure is explained and the performance of this approach critically assessed. 

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