Effect of temperature on acid-?base equilibria in separation techniques. A review

GAGLIARDI, L. G; TASCÓN, M.; CASTELLS, C. B.

ANALYTICA CHIMICA ACTA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015

0003-2670

Studies on the theoretical principles of acid-?base equilibria are reviewed and the influence of temperature on secondary chemical equilibria within the context of separation techniques, in water and also in aqueous-organic solventmixtures, is discussed. In order to define the relationships between the retention in liquid chromatography or the migration velocity in capillary electrophoresis and temperature, the main properties of acid-?base equilibria have to be takeninto account for both, the analytes and the conjugate pairs chosen to control the solution pH. The focus of this review is based on liquid?liquid extraction (LLE), liquid chromatography (LC) and capillary electrophoresis (CE), with emphasison the use of temperature as a useful variable to modify selectivity on a predictable basis. Simplified models were evaluated to achieve practical optimizations involving pH and temperature (in LLE and CE) as well as solvent compositionin reversed-phase LC.