ION CHROMATOGRAPHY BY INDIRECT UV-PHOTOMETRIC DETECTION OF ANIONS USING TRIMELLITATE AS AN ELUENT

A simple, sensitive, and convenient method of ion chromatography (IC) by indirect UV-photometry for the simultaneous determination of five common anions (PO43-, Cl-, NO2-, NO3- and SO42-) was established using a Trimellitate (1,2,4-benzenetricarboxylate)/methanol eluent and a low capacity silica-based anion-exchange column (TSK-guardgel QAE-SW; capacity: ca. 0.3 meq./g; 4.6 mm i.d. X 15 cm). A good separation and detection of the anions was accomplished within 20 min by the IC with a 0.5 mM Trimellitate/20% methanol eluent at pH 6.0 and UV-detection at 270 nm. The detection sensitivities of the anions by the present method were 2 approximately 3 times higher than those by the previous method (IC by conductometric detection using a 1.25 mM Trimellitate eluent at pH 4.65). The present method was successfully applied to the determination of anions in river water samples with no interference from HCO3- and Mg2+- and Ca2+-Trimellitate complexes.