Indirect fluorometric detection for non-suppressed ion chromatographic separation of analyte anions using ruthenium(II) complex as ion-interaction reagent

Abstract

Factors affecting the use of Ru(phen)3(ClO4)2 as an ion-interaction reagent for indirect fluorometric detection of simple analyte anions separated by non-suppressed ion chromatography were investigated with an aim to obtain a sensitive method for detection at ng ml-1 level. The intense UV π-π(*) transition band at 261 nm and the ligand-metal charge transition at 447 nm for excitation were compared at different eluent and chloride concentrations. The excitation wavelength of 447 nm was selected as it gave a higher sensitivity and a longer working range. Ru(phen)3(ClO4)2 was chosen as the eluent at 0.01 mM which gave the best signal to noise ratio. Detection limits (peak = 2 σ) much lower than those reported in the literature using similar indirect photometric or fluorometric detection were obtained for F-, Cl-, Br- and NO3 - at concentration (total amount) of 3 ng ml-1 (0.06 ng), 2 ng ml-1 (0.04 ng), 5 ng ml-1 (0.1 ng), and 5 ng ml-1 (0.1 ng) respectively. This will provide a non-suppressed ion chromatography procedure with sufficient sensitivity to meet the demand for trace anion analysis for environmental, industrial and other applications requiring detection limits at ng ml-1 concentration.