Simultaneous Separation of Neutral Organics and Inorganic Anions by Coupling Reversed‐Phase and Ion‐Interaction Chromatography

Abstract

Ion‐interaction chromatography is coupled with reversed‐phase HPLC to effect simultaneous separation of inorganic anions and neutral organic species. The column is a standard C₁₈, and the mobile phase is an aqueous combination of typical ion‐interaction and reversed‐phase constituents, an ion‐interaction reagent and an organic cosolvent (methanol). Anions and small, polar, organic mixtures were separated in relatively low methanol content mobile phases (40–60%, v/v) with tetrabutylammonium and tetraheptylammonium ion‐interaction reagents. Mixtures of anions and nonpolar organics (PAHs) required higher methanol content with a relatively hydrophobic ion‐interaction reagent, cetyltrimethylammonium chloride. In all cases, mobile phase conditions could be adjusted to allow anions and neutral organics to be separated both between and within classes.

Keywords:

• Ion‐interaction
• Ion‐pairing
• Anion‐exchange
• Mixed‐class separation
• Mobile‐phase composition