Tris(2,2′-bipyridyl)ruthenium(II)–Zirconia–Nafion composite modified electrode applied as solid-state electrochemiluminescence detector on electrophoretic microchip for detection of pharmaceuticals of tramadol, lidocaine and ofloxacin

Tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+)–Zirconia–Nafion composite modified glassy carbon disk electrode as a solid-state electrochemiluminescence (ECL) detector is successfully applied to an electrophoretic microchip system with a wall-jet configuration. Pharmaceuticals such as tramadol, lidocaine and ofloxacin were selected to characterize the performance of this microchip capillary electrophoresis (CE)–ECL detection system. Voltammetric and ECL behaviors of immobilized Ru(bpy)32+ were investigated in lidocaine system. Influences of the separation electric field to cyclic voltammograms (CVs) of the immobilized Ru(bpy)32+ were also investigated. Tramadol, lidocaine and ofloxacin can be baseline separated without any additives. The detection limits (S/N = 3) were 2.5 × 10−5 mol L−1 for tramadol, 5.0 × 10−6 mol L−1 for lidocaine, 1.0 × 10−5 mol L−1 for ofloxacin under the sample injection of picoliters, and the linear ranges were from 5.0 × 10−5 to 2.5 × 10−3 mol L−1 for tramadol, 1.0 × 10−5 to 1.0 × 10−3 mol L−1 for lidocaine, and 1.0 × 10−5 to 2.5 × 10−3 mol L−1 for ofloxacin, respectively.