Optimization of Chromatographic Systems for Determination of Lipophilicity for Selected Isoquinoline Alkaloids

Abstract

Nine isoquinoline alkaloids were investigated on C18 stationary phase in different eluent systems containing acetonitrile, methanol, tetrahydrofuran, and dioxane as organic modifier with addition of buffers at different pH, ion pairing reagents, or silanol blockers. The dependencies between the concentration of organic modifier and retention parameters were plotted. Log kw values were determined by the extrapolation method. The values, obtained in different eluent systems, were correlated with a predicted lipophilicity parameter (log P). The correlations between chromatographic values and predicted lipophilicity values are different, depending on the eluent system applied and the estimation method concerning partition coefficients: octanol/water. The best correlations were obtained for eluents containing the addition of ion pair reagents, especially for systems containing the sodium dodecyl sulfate.