RETENTION PREDICTION BASED ON MOLECULAR-INTERACTIONS IN PACKED-COLUMN SUPERCRITICAL-FLUID CHROMATOGRAPHY

A model for retention prediction in packed-column supercritical fluid chromatography based upon multicomponent solubility parameters, delta(d), delta(o), delta(in), delta(a), and delta(b), is proposed. These parameters are direct measures of a solute's ability to partake in dispersive, dipole-dipole, dipole-induced dipole, and hydrogen-bonding acidic and basic interactions, respectively. Retention data for a series of aromatic molecules of form Ph-X was obtained on ODS, phenyl, nitrile, and amino bonded phases and bare silica. Carbon dioxide at a pressure of 114-135 bar modified with up to 20% methanol at a temperature of 60 degrees C was used as mobile phase. Retention is described by an equation of the form ln k' = V-m(a delta(d) + b delta(o) + c delta(in) + d delta(a) + e delta(b) + f), where V-m represents molar volume, k' represents capacity factor, and a-f are weighting coefficients. The model is used to derive delta values for new compounds and is extended to retention prediction for disubstituted aromatics.