Electrochemiluminescent behaviors of alkaloids and tris(2,2′-bipyridine) ruthenium in organically modified silicate film

Electrogenerated chemiluminescences (ECLs) of alkaloids, such as berberine, trigonelline, allantoin and betaine, were studied in an aqueous alkaline buffer solution (pH 9.5), based on tris(2,2′-bipyridine)ruthenium(II) [Ru(bpy)32+] immobilized in organically modified silicates (ORMOSILs) film on a glassy carbon electrode (GCE). The immobilized Ru(bpy)32+ showed good electrochemical and photochemical activities. In a flow system, the eluted alkaloids were oxidized on the modified GCE, and reacted with immobilized Ru(bpy)32+ at the potential of +1.50 V (versus Ag/AgCl). The luminescence with λmax 610 nm was caused by a reaction of electrolytically formed Ru(bpy)33+ with an oxidized amine group to generate Ru(bpy)32+*. The determination limit was 5 × 10−6 mol L−1, 8 × 10−6 mol L−1, 2.0 × 10−5 mol L−1 and 5.0 × 10−5 mol L−1 for berberine, trigonelline, allantoin and betaine at S/N 3, respectively. In addition, the factors affecting the determination of the four alkaloids were also studied.