Non-suppressed ion chromatography of inorganic anions, magnesium and calcium ions using a pyromellitate eluent and its application in evaluating environmental water quality

A simple, sensitive and convenient ion chromatographic (IC) method with UV photometric detection using pyromellitate (1,2,4,5-benzenetetracarboxylate)-methanol-water as the eluent on a silica-based anion-exchange column was established for the simultaneous determination of common inorganic anions including HCO3-, Mg2+ and Ca2+ in environmental waters. The anions were detected indirectly, whilst Mg2+ and Ca2+ were detected directly because complexes having strong UV absorption were formed between pyromellitate and these cations. The proposed method was successfully applied to the simultaneous determination of the common anions, Mg2+ and Ca2+ in various river water samples.