SIMULTANEOUS DETERMINATION OF TOTAL CARBONATE AND COMMON INORGANIC ANIONS IN ENVIRONMENTAL WATERS BY ION CHROMATOGRAPHY WITH INDIRECT UV-PHOTOMETRIC DETECTION USING BENZENEPOLYCARBOXYLATE ELUENT

In order to determine simultaneously major inorganic anions including total carbonate and common inorganic anions (Cl-, NO2-, NO3-, and SO42-) in various environmental waters, the ion chromatography with an indirect UV-photometric detection using various benzenepolycarboxylate (o-phthalate, 1,2,4-benzenetricarboxylate, and 1,2,4,5-benzenetetracarboxylate) eluents and columns packed with a silica-based anion-exchanger (TSKguardgel QAE-SW, capacity: ca. 0.3 mmol OH-/g) were investigated. When a 0.5 mmol/dm(3) 1,2,4-benzenetricarboxylate eluent at pH 6.0 and a 15 cm separation column were used, the best separation and detection sensitivity of the anions were accomplished within 15 min without the interference of coexisting Mg2+ and Ca2+ in sample solution. The detection limits (S/N=3, injection volume: 20 mu l) under the indirect UV-detection at 270 Mn were 240 ng/ml for HCO3-, 15 ng/ml for Cl-, 22 ng/ml for NO2-, 33 ng/ml for NO3-, and 48 ng/ml for SO42-. The calibration graphs by peak area method were linear up to at least 10 mmol/dm(3) for HCO3-, 2 mmol/dm(3) for monovalent anions, and 1.5 mmol/dm(3) for SO42-. This method was successfully applied for the determination of the anions in various environmental waters including river, pond, and forest soil waters.