CONTRIBUTIONS TO THE CALCULATION OF RETENTION DATA IN ION-PAIR CHROMATOGRAPHY

The retention behaviour of organic bases (m-ando-aminophenol, dopamine was investigated in the pH range 2,5-6,8 using aqueoys phosphate buffer and constant ionic strength. The capacity factors were determined on two ODS-silica columns in the absence and presence of sodium octylsulphonate. Using the calculated values of the hydrophobic capacities of the columns, a logarithmic relationship is proposed between the capacity factor of the non-protonated base in the absence and presence of the ion-pairing reagent and the actual hydrophobic capacity of the column. For the retention ratios of the protonated base species, the electrostatic theory introduced by Stahlberg proved to be acceptable. At low pH the protonation of theory octylsulphonate ion is also considered. The calculated and experimantally obtained capacity factors show acceptable agreement with each other. © 1990.