Development of a novel chemiluminescence detection system in ion chromatography

Novel sensitive chemiluminescence (CL) systems were developed and it was applied for detection in ion chromatography (IC). It was difficult to combine CL detection with IC because considerable differences exist in the optimum operating condition for each system. eluent, BaCl2, for both luminol (Lm)/H2O2/KOH-CL and IC was, however found. was possible to detect Co(II) selectively with 1.0 pg ml(-1) detection limit (DL), Similarly, combination of CL and ion exclusion mode IC was examined to determine weak acid anions like silicate. Millimolar concentrations of HClO4 was effective as eluent and also resulted in their elution of the anions in their unionized molecular acid form. The molecular acids cause Cb, by acting as a catalyst in the oxidation of Lm by H2O2 and dissolved oxygen. However, there is considerable background CL emission generated by Lm and H2O2 in the absence of any analyte. It was found that this background CL was dramatically reduced by eliminating H2O2, and the weak acids also causes CL even in the absence of H2O2. Lower DL of 0.10 ng ml(-1) Si(IV) was obtained under this condition. Moreover, when Lm itself was eliminated from the CL reagent leaving only KOH in the reagent, faint CL emission generated by the neutralization of HNO3 and KOH was obtained. When IC was conducted with a KOH eluent and HNO3 was mixed with the column effluent continuously in a post column reaction mode, the CL was quenched quantitatively by anions eluted from IC. Halide and oxo-anions were detected at ng ml(-1) levels with enough separation to give no interference each other. These results appeared that these CL methods were useful to determine inorganic ions, especially anions.