Dependence of the retention of some barbituric acid derivatives on a porous graphitized carbon column on their physicochemical parameters.

The retentions of 45 barbituric acid derivatives were determined on a porous graphitized carbon column (PGC) in unbuffered methanol-water eluent mixtures at various organic phase concentrations and the retention data were correlated with the various hydrophobic and electronic parameters of barbituric acid derivatives. Each derivative showed symmetric peaks in each eluent proving the good separation characteristics of the PGC column without buffering the eluent. Significant linear correlations were found between the logk' value and the concentration of the organic mobile phase in the eluent. Stepwise regression analysis indicated that the retention of barbituric acid derivatives is mainly governed by the electronic parameters, and the lipophilicity of various substituents did not affect significantly the retention, although the eluents were typical reversed-phase eluents.