Carbon dioxide-enhanced luminol chemiluminescence in the absence of added oxidant

Abstract

Carbon dioxide significantly enhances the chemiluminescence of 5-amino-2,3-dihydrophthalazine-1,4-dione (luminol) in the absence of added oxidant. The effect in presence of a variety of rate modifiers (e.g., metal ions and some metal ion complexes) is described in detail. A postulation of the species responsible for enhancement, the role of dissolved oxygen, the influence of the form in which the rate modifier is present and a possible mechanism to explain the enhancement by CO₂(g), are also presented. The potential analytical applications of this effect are mentioned and illustrated with the analytical figures of merit for the chemiluminescence determination of Co^II in the 5 × 10^–13–10^–7 mol l^–1 range.