Chromatography of inorganic anions on poly(vinyl alcohol) gel columns with acidic eluents

Abstract

Poly(vinyl alcohol) (PVA) gel shows ionic retention properties for common inorganic anions when an acidic eluent is used. The ionic property of the PVA gel is due to the proton-acceptable nitrogen atoms of the cross-linking agent and the carboxylic residues being comprised in the gel matrix. The extent of the net charge on the gel surface depends on the pH of the eluent. At a pH ranging from 2.3 to 5.3, the PVA gel behaves as a weak anion exchanger with very low ion-exchange capacity. At these conditions four UV-absorbing inorganic anions (bromate, bromide, nitrate, and nitrite) are separated by eluting with aqueous sulfuric acid. Alkyl groups introduced on the gel surface hinder the ionized solute molecules from accessing to the positively charged functional groups on the gel surface. A neutral solute (HNO2) is retained with non-ionic interactions.