RETENTION BEHAVIOR OF SOME BARBITURIC-ACID DERIVATIVES ON A POLYETHYLENE-COATED SILICA COLUMN

The retention of 45 barbituric acid derivatives was determined on a po lyethylene-coated silica column (PEE) in unbuffered methanol-water elu ent mixtures. Each derivative showed a symmetric peak shape in each el uent and the capacity factor decreased monotonously with increasing co ncentration of methanol in the eluent. Stepwise regression analysis in dicated that the retention of barbituric acid derivatives is mainly go verned by the molecular lipopholicity and, to a lesser extent, by ster ic effects of the various substituents. This finding indicates that th e polyethylene-coated silica behaves as a real reversed-phase chromato graphic support with slightly different retention characteristics.