Letter: Detection of reaction intermediates by flow injection electrospray ionization mass spectrometry: reaction of chemiluminescent N-sulfonylacridinium-9-carboxamides with hydrogen peroxide

Flow injection electrospray mass spectrometry was used to detect the intermediates and products formed during the reaction of chemiluminescent acridinium salts under the conditions necessary for light emission. A stream of aqueous alkaline hydrogen peroxide was mixed with an aqueous solution of N-sulfonylacridinium-9-carboxamide salt immediately prior to entering the ESI-MS interface. The resulting negative-ion mass spectra corresponded to the expected 9-hydroperoxide adduct, the acridone end product normally seen in the chemiluminescent reaction, and unreacted acridinium salt, with no indication of the postulated spirodioxetanone intermediate or competing pseudobase.