ACD/Labs 5^th Annual European Users' Meeting 2004 (EUM)

The Advantages of Predicting pK_a in Chromatographic Method Development

Mike McBrien

Abstract

The strong influence of pH on chromatographic performance has implications to the robustness of chromatographic methods as well as absolute retention times. The high sensitivity of retention time to pH leads to concerns about the reproducibility of separations when designing methods to be applied in the long term. Thus effective approaches to pH choice are particularly important when stable, reproducible separations are sought. In addition, targeted changes in ionization state can enable the chromatographer to target different selectivities where necessary.

Effective mobile phase pH levels can be determined on a purely experimental basis, but this time-intensive process can be facilitated greatly through the use of any knowledge that the chromatographer has regarding expected structure(s) and/or functional groups. ACD/LC Simulator's pK_a prediction algorithm combined with user training is an efficient way to take advantage of organizations' physicochemical measurements supplemented with calculated pK_as. This discussion will describe the practical application of knowledge of ionization sites (predicted and/or experimental) for analytes prior to, and during, chromatographic method development.

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Relevant Products: Method Development Suite, LC Simulator

Relevant Solution: Chromatographic Method Development