Correlation between hydrophobicity and retention data of several antihistamines in reversed-phase liquid chromatography with aqueous-organic and micellar-organic mobile phases

The correlation between the retention of 12 antihistamines (carbinoxamine, chlorpheniramine, cyclizine, cyproheptadine, dexbrompheniramine, dexchlorph eniramine, diphenhydramine, doxylamine, pheniramine, phenyltoloxamine, pyri lamine and tripelennamine), in reversed-phase liquid chromatography (RPLC) with aqueous-organic (methanol-water) and micellar-organic (sodium dodecyl sulphate (SDS)-pentanol) mobile phases of varying composition, and their oc tanol-water partition coefficients expressed as log P-o/w (ranging between 2.02 for pheniramine and 4.92 for cyproheptadine), was examined. For this s tudy, the retention of the drugs was measured in six mobile phases of metha nol-water, and seven mobile phases of SDS-pentanol, which permitted to obta in the coefficients of model equations that described the retention for any mobile phase composition inside the considered factor space (0.40-0.70 (v/ v) methanol, or 0.05-0.15 M SDS and 0.02-0.06 (v/v) pentanol). Log k versus log P-o/w plots gave better correlations than k versus log P-o/w plots, an d the maximal regression coefficients were the same for both aqueous-organi c and micellar-organic RPLC. In both techniques, there was a range of mobil e phase compositions where the correlations were similar (r=0.96-97): 0.55- 0.70 (v/v) methanol and 0.05-0.09 M SDS/0.05-0.06 (v/v) pentanol. Good corr elations were found in micellar-organic RPLC between the extrapolated reten tion factor at zero micelle and organic modifier concentrations (r=0.964), and log P-o/w, and between the inverse of the solute-micelle association co nstant and log P-o/w (r=0.986). (C) 2000 Elsevier Science B.V. All rights r eserved.