title: Fast and direct method for measuring 1-octanol-water partition coefficients exemplified for six local anesthetics.
abstract: The 1-octanol-water partition coefficients (P(OW)) of six local anesthetics were determined by an improved direct method. In the experimental setup, dialysis tubing is used to separate the aqueous from the octanol phase containing the analyte. This procedure allows the application of ultrasonic agitation to shorten the equilibration time to 2 h. The measurements had a reproducibility of +/- 0.1 log units and showed an excellent agreement with the results obtained with the traditional shake-flask method. However, the correlation with the indirect determination using reversed-phase liquid chromatography was considerably poorer, showing that high-performance liquid chromatography determinations are not always very reliable. Because all the anesthetics used are nitrogen bases, the measurements were performed at two pH values. The method allows a fast and reliable direct determination of partition coefficients.
authors.affiliation: Institute of Inorganic and Analytical Chemistry, University of Münster, Wilhelm-Klemm-Str. 8, D-48145 Münster, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Schräder
authors.forename: J T
authors.initials: JT
authors.lastname: Andersson
mesh_terms: D020003:1-Octanol / Q000737:chemistry*; D000779:Anesthetics, Local / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006863:Hydrogen-Ion Concentration; D012107:Research Design; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000779:Anesthetics, Local; D012997:Solvents; D014867:Water; D020003:1-Octanol