Electrogenerated chemiluminescence quenching of Ru(bpy)3 2+ (bpy=2,2′-bipyridine) in the presence of acetaminophen, salicylic acid and their metabolites

Quenching of Ru(bpy) 32+ (bpy=2,2′-bipyridine) coreactant electrogenerated chemiluminescence (ECL) has been observed in the presence of acetaminophen, salicylic acid and related complexes. However, no quenching is observed with the acetylsalicylic acid. In most instances, quenching is observed with 100-fold excess of quencher (compared to ECL luminophore) with complete quenching observed between 10,000 and 100,000 fold excess. Fluorescence and UV–vis experiments coupled with bulk electrolysis support the formation of benzoquinone products upon electrochemical oxidation. The mechanism of quenching may involve the interaction of the electrochemically generated benzoquinone species with (i) the ⁎Ru(bpy)32+ excited state or (ii) highly energetic coreactant radicals.