Indirect determination of octanol-water partition coefficients by microemulsion electrokinetic chromatography

Recent advances in the development and application of microemulsion EKC

“…Migration times have been found to decrease with increase in pH [33,35] as higher pH values generate a greater EOF. Buffers up to pH 12 have been used for basic compounds [59] to eliminate ionisation and for acidic compounds, a low pH buffer is required (pH 1.2-1.4). Because at low pH there is little or no EOF generated, a negative voltage needs to be applied across the capillary in order to move the droplets through the detector, which results in the most retained compounds being detected first [31,60].…”

Studies on equilibrium of anthranilic acid in aqueous solutions and in two-phase systems: Aromatic solvent–water

“…It makes accurate determination of isoelectric point impossible (knowledge of this point value is necessary for the proper determination of the tautomerization K z microconstant). Literature data concerning pH I are in disagreement (pH I 3.42 [13], pH I =3.44 [26] and pH I 3.51 [18]). For this reason in the present work the mixed dissociation constants (I=0.1, KCl) of anthranilic acid have been determined on the basis of potentiometric titration.…”

“…Literature data concerning pK a2 value of anthranilic acid appear to be unreliable and depending on the information source have a value between 4.59 and 4.97 [13,18,24,25,26].…”

“…There are considerably less data concerning pK a1 value (pK a1 = 2.15 [13], pK a1 = 2.17 [18] and pK a1 = 2.29 [26]. It makes accurate determination of isoelectric point impossible (knowledge of this point value is necessary for the proper determination of the tautomerization K z microconstant).…”

Membrane‐mediated capillary electrophoresis: Interaction of cationic peptides with bicelles

“…As a result, the extent of analyte partitioning in the micelles or bicelles can be deduced from migration time measurements. Studies based on electrokinetic chromatography methods have correlated capacity factor or retention factor with octanol water partition coefficients, which in turn is used to estimate membrane permeability [2][3][4]. However, the degree of membrane partitioning, reported as a capacity factor or retention factor, may correlate better with membrane solubility or lipophilicity than octanol water partitioning.…”