Preliminary electrochemiluminescence study of allantoin in the presence of tris(2,2'-bipyridine) ruthenium (II).

Electrochemiluminescence (ECL) based on allantoin and tris(2,2'-bipyridine)ruthenium (II) [Ru(bpy)3 (2+)] was studied in aqueous alkaline buffer solution (pH 11.0). In a flowing system, the eluted allantoin was mixed with 1.0 mmol/L Ru(bpy)3 (2+). When the solution passed through a thin layer flow electrolytic cell equipped with a glassy carbon disc electrode (22.1 mm2), both hydroxyl groups of allantoin and Ru(bpy)3 (2+) were oxidized at the potential of +1.50 V (vs. Ag/AgCl). The luminescence with lambdamax 610 nm caused by the reaction of electrolytically formed Ru(bpy)3 (2+) with alkoxide radical to generate the excited state of Ru(bpy)3 (2+*). A possible ECL process of allantoin in Ru(bpy)3 (2+) alkaline solution has been discussed. In addition, the factors affecting the ECL response of allantoin are also investigated.