ONLINE LINEAR SWEEP VOLTAMMETRY ELECTROSPRAY MASS-SPECTROMETRY

A three-electrode electrochemical cell coupled to an electrospray (ES) mass spectrometer has been developed and employed for on-line linear sweep voltammetry-ES mass spectrometry and electrochemical reaction st udies. Generated in this type of electrochemistry/mass spectrometry (E C/MS) experiment are ion abundance vs potential profiles that provide molecular weight and structural information pertaining to intermediate s and products of anodic oxidation of diphenyl sulfide, anodic pyridat ion of 9,10-diphenylanthracene, and reduction of nitrobenzene, Anodic oxidation of diphenyl sulfide in methylene chloride media at the plati num electrode yielded diphenyl sulfoxide and pseudodimer sulfonium ion along with products of further oxidation. The obtained ion abundance vs potential profiles offer additional evidence to corroborate previou sly proposed reaction mechanisms for pseudodimer sulfonium ion generat ion from diphenyl sulfide, as well as pyridine addition to DPA radical cation also in methylene chloride at the platinum electrode. From the latter experiment, a newly found reaction product, [DPA(py)-H](+), is reported. Despite the inherent tendency of ES devices to induce oxida tion processes in the positive ion mode, intermediates and products of nitrobenzene reduction in nonaqueous and organic/water media were det ected in both negative and positive ES modes.