STUDY OF THE EFFECT OF MOBILE-PHASE ADDITIVES ON RETENTION IN REVERSED-PHASE HPLC USING LINEAR SOLVATION ENERGY RELATIONSHIPS

Linear solvation energy relationships (LSERs) were used to delineate w hich specific intermolecular interactions are responsible for changes in retention for a variety of well characterized analytes when acidic and basic additives were used in reversed phase HPLC. The effects of t rifluoroacetic acid, triethylamine and a combination of trifluoroaceti c acid and triethylamine on the LSERs were compared to those observed in the absence of additives. These effects were examined using four di fferent mobile phase modifiers and five different stationary phases, T rifluoroacetic acid alone and in combination with triethylamine produc ed LSER regression coefficients nearly identical to those obtained wit h no additive present in the mobile phase. Triethylamine alone produce d different LSER regression coefficients from the other systems unless the mobile phase contained trifluoroethanol as the mobile phase modif ier, or the stationary phase consisted of a polymeric support.