The effects of solvent preoxidation on inhibited chemiluminescence of pyrogallol oxidation in flow injection analysis and liquid chromatography

Abstract

A new extension of chemiluminescence technique using pre-oxidation of a carrier solvent before the conventional inhibited chemiluminescence detection is presented in this study. The method is based on the modification of the oxidation chemistry of pyrogallol upon contact with a flow stream consisting of an organic solvent in mixture with an aqueous solution of a soft oxidant. The final response was found to depend on the kind of solvent and the oxidant/pre-oxidant mixture employed for the oxidation of pyrogallol and the solvent, respectively. By selecting the appropriate combination two detection modalities with increased sensitivity can be achieved. The first is based on the enhancement of the analytes signal through intensification of their scavenging effect on pyrogallol oxidation and the second on the enhancement of signal above the emission induced during the pyrogallol oxidation. Various combinations of organic solvents, oxidizing and pre-oxidizing mixtures were examined for their response in inhibited chemiluminescence measurements yielding very interesting results. The analytical utility of this new technique to the improvement of previous analytical methods as well as to the development of new procedures employing flow injection analysis is demonstrated. Furthermore, the application of the proposed method in combination with liquid chromatographic analysis is also presented.