title: Effect of n-octanol in the mobile phase on lipophilicity determination by reversed-phase high-performance liquid chromatography on a modified silica column.
abstract: In this study, we show that the addition of n-octanol to the mobile phase improves the chromatographic determination of lipophilicity parameters of xenobiotics (neutral solutes, acidic, neutral and basic drugs) on a Phenomenex Gemini C18 column. The Gemini C18 column is a new generation hybrid silica-based column with an extended pH range capability. The wide pH range (2-12) afforded the examination of basic drugs and acidic drugs in their neutral form. Extrapolated retention factor values, [Formula: see text] , obtained on the above column with the n-octanol-modified mobile phase were very well correlated (1:1 correlation) with literature values of logP (logarithm of the partition coefficient in n-octanol/water) of neutral compounds and neutral drugs (69). In addition, we found good linear correlations between measured [Formula: see text] values and calculated values of the logarithm of the distribution coefficient at pH 7.0 (logD(7.0)) for ionized acidic and basic drugs (r(2)=0.95). The Gemini C18 phase was characterized using the linear solvation energy relationship (LSER) model of Abraham. The LSER system constants for the column were compared to the LSER constants of n-octanol/water extraction system using the Tanaka radar plots. The comparison shows that the two methods are nearly equivalent.
authors.affiliation: Institute of Chemistry, The Hebrew University of Jerusalem, Edmund Safra Campus, 91904 Jerusalem, Israel.
authors.forename: Deborah
authors.initials: D
authors.lastname: Benhaim
authors.forename: Eli
authors.initials: E
authors.lastname: Grushka
mesh_terms: D020003:1-Octanol / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation* / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide; D020003:1-Octanol