POSSIBLE ROLE FOR STATIONARY PHASE METAL INTERACTIONS IN THE CHROMATOGRAPHY OF HYDROXYAMINES ON SILICA

Problems associated with the non-elution or peak tailing of dihydroxyamines on silica with methanol-aqueous buffer mobile phases have been investigated. The problem is confined to molecules where the hydroxy groups are phenolic in nature and ortho to one another. Study of a controlled set of compounds shows that non-elution/elution with poor peak shape is a function of the distance between the dihydroxy and amine moieties. In terms of the stationary phase, the problem appears to be related to the metal content of the silica. Demineralisation of the silica by acid washing was ineffective, however, flushing the column with EDTA resulted in elution of all dihydroxyamines with improved peak shape.