Retention Dependence on Organic Modifier and Interaction Reagent Concentration in Reversed-Phase Ion-Interaction HPLC

Abstract

Abstract The effect played on ion-interaction chromatographic retention by the concentrations of the organic modifier and of the ion-interaction reagent as a function of the ionic strength is studied. Experiments are performed for a series of analytes characterized by different chemical properties (nitrate, nitrite, iodide, ascorbic, orotic and p-aminobenzoic acids, aniline, benzylamine, p- and m-aminophenol) in the absence and in the presence of organic modifiers (acetonitrile and methanol) and of sodium perchlorate to control the ionic strength (I=1.0 M). Concentrations of the ion-interaction reagent (octylammonium o-phosphate) ranging between 1.0 and 60.0 mM and of the organic modifier (methanol and acetonitrile) ranging between 0 and 45% are considered. Retention interdependence on the concentrations of ion-interaction reagent and of the methanol in the mobile phase is also studied. The results are discussed and compared with literature data and the relevant role played on the retention by ionic stren...