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

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 x 10(-13)-10(-7) mol l(-1) range.