Solvent strength and selectivity on a porous graphitized carbon column separated by a spectral mapping technique using barbiturates as solutes.

A spectral mapping technique (SPM) was employed for separating the strength and selectivity of the retention of 41 barbituric acid derivatives and 5 organic modifiers on a porous graphitized carbon column (PGC). The potency values calculated by SPM were considered to be indicators of the capacity of drugs to bind to the surface of PGC and the capacity of organic modifiers to remove the drugs from the surface. The dimensionality of the multidimensional selectivity maps was reduced to two by a nonlinear mapping technique. Calculations indicated that molecular lipophilicity plays a negligible role in the strength and selectivity of retention, proving that the retention mechanism of PGC deviates from those of traditional reversed-phase stationary phases. Sterical and electronic parameters exerted the highest influence on the retention, emphasizing the importance of the polar interaction and the sterical correspondence between the surface of PGC and the solute molecules.