Simultaneous optimization of reagent concentration and pH in reversed-phase ion-pairing chromatography

The Column in Liquid Chromatography

“…Generally, the retention of oppositely charged ionic solutes increases with increasing hydrophobicity (increasing chain length) of the pairing ions when used at identical mobile phase concentrations [370][371][372]. Since the mobile phase concentration of the pairing ion and the organic modifier both affect the surface concentration of the pairing ion, these variables should have the greatest effect on solute ion retention, and should be used for adjusting the mobile phase elution strength [374][375][376]. It has been shown that alkylsulfonate pairing ions of different chain length result in identical solute retention at similar surface concentrations [372].…”

“…For chemically bonded reversed-phase columns, the working range is about pH 2-8. Computer-guided strategies are available for varying these parameters simultaneously, and for using preselected gradient conditions to estimate reasonable starting conditions for samples of unknown origin [368,[373][374][375]379]. can occur.…”

“…Several theoretical models, such as the ion-pair model [342,3 60,3 61, 3 63,380], the dynamic ion-exchange model [342,362,363,375] and the electrostatic model [342,369,[381][382][383][384][385][386] have been proposed to describe retention in reversed-phase IPC. The electrostatic model is the most versatile and enjoys the most support but is mathematically complex and not very intuitive.…”