The effect of a mobile phase additive on the retention characteristics of different solute types on reversed-phase media

Abstract

Mobile phase additives, e.g., cyclodextrins and ion-pairing reagents, have been used for the specialist separation of enantiomers and ionic species. In this paper, the use of an additive for mediating the retention characteristics of general solutes on a reversed-phase is described. A C₄ aliphatic compound, valeronitrile, has been investigated as a potential mobile phase additive in base solvents consisting of methanol–water mixtures. A range of test solutes have been chromatographed at various levels of valeronitrile concentration on a commercial C₈ bonded reversed-phase, and their retention characteristics compared. The results obtained show that relatively small amounts of valeronitrile can cause a significant change in retention, and further, can significantly improve the chromatography of basic compounds.