Reversed-phase liquid chromatography gradient optimization

The popularity of reversed-phase liquid chromatography (RPC) is easily explained by its unmatched simplicity, versatility and scope [15,22,50,52,71,149,288-290]. Neutral and ionic solutes can be separated simultaneously and the rapid equilibration of the stationary phase with changes in mobile phase composition allows gradient elution techniques to be used routinely. Secondary chemical equilibria, such as ion suppression, ion-pair formation, metal complexatlon, and micelle formation are easily exploited in RPC to optimize separation selectivity and to augment changes availaple from varying the mobile phase solvent composition. Retention in RPC, at least in the accepted ideal sense, occurs by non-specific hydrophobic interactions of the solute with the... 

Others have examined the necessary parameters that should be optimized to make the two-dimensional separation operate within the context of the columns that are chosen for the unique separation applications that are being developed. This is true for most of the applications shown in this book. However, one of the common themes here is that it is often necessary to slow down the first-dimension separation system in a 2DLC system. If one does not slow down the first dimension, another approach is to speed up the second dimension so that the whole analysis is not gated by the time of the second dimension. Recently, this has been the motivation behind the very fast second-dimension systems, such as Carr and coworker s fast gradient reversed-phase liquid chromatography (RPLC) second dimension systems, which operate at elevated temperatures (Stoll et al., 2006, 2007). Having a fast second dimension makes CE an attractive technique, especially with fast gating methods, which are discussed in Chapter 5. However, these are specialized for specific applications and may require method development techniques specific to CE. 

G. Vivo-Truyols, J.R. Torres-Lapasio and M.C. Garcia-Alvarez-Coque, Enhanced calculation of optimal gradient programs in reversed-phase liquid chromatography. J. Chromatogr.A 1018 (2003) 183-196. 

Nikitas, P. Pappa-Louisi, A. Papageorgiou, A. Simple algorithms for fitting and optimization for multilinear gradient elution in reversed-phase liquid chromatography. J. Chromatogr. A, 2007,1157, 178-186. 

Stadalius, M. A., Gold, H. S., and Snyder, L. R., Optimization model for the gradient elution separation of peptide mixtures by reversed-phase high-performance liquid chromatography. Verification of retention relationships, /. Chromatogr., 296, 31, 1984. 

Fast optimizing of the multi-segment gradient profile in reversed-phase high performance liquid chromatography using the Monte Carlo method, LC-GC Int. Mag. 8, N 10 (1995), 581-587. 

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