Abstract
The retention indices of 17 drugs and metabolites including hypnotics, antiepileptics, analgesics, and central nervous system stimulants in liquid-liquid chromatography were systematically examined to devise a highly efficient extraction and fractionation procedure in biological fluid analysis. A high performance system incorporating an acid-treated silica gel column and a UV-detector was assembled to determine the capacity ratios in aqueous two phase organic solvents consisting of diethyl ether and n-hexane (1 : 0, 7 : 3, 1 : 1, 3 : 7 v/v). The corrected capacity ratios (k'cor) of the drugs in an aqueous organic phase system were calculated from the experimental retention data and phase ratios in liquid-liquid chromatography. A linear correlation between the logarithm of the k'cor value and the logarithm of solvent composition in a liquid-liquid partition system was demonstrated in this study.
