THE DERIVATIVE ADSORPTION CHRONOPOTENTIOMETRY OF FLAVIN ADENINE-DINUCLEOTIDE

The flavin adenine dinucleotide (FAD), leucoflavin adenine dinucleotid e (FADH(2)) couple was studied by derivative adsorption chronopotentio metry al a HMDE. The theory of an EE mechanism for adsorption chronopo tentiometry was developed and the semiquinone formation constant deter mined. Constant current stripping results at pH 7.0 were consistent wi th previous reports that adsorbed FAD was reduced via a stable semiqui none intermediate in two reversible one-electron transfers (EE mechani sm). Potentiometric stripping analysis was also carried out in which t he FAD was accumulated as FADH(2) on the HMDE at a reducing potential. The FADH(2) was subsequently oxidized by dissolved oxygen. This react ion was also found to fit the EE model.