Development of Electrochemiluminecence Sensor for Verapamil Hydrochloride Based on TiO₂ sol/ZnO@Ag/Silica sol-Ru(bpy)₃²⁺ Modified Pyrolytic Graphite Electrode (Supporting Information)

<p>A sensitive solid-state electrochemiluminesence (ECL) sensor for verapamil hydrochloride (VpCl) was fabricated based on the film formability of TiO₂ sol and electrocatalysis of ZnO@Ag. The immobilization of tris(2, 2′-bipyridine) ruthenium (II) (Ru(bpy)₃²⁺) by using TiO₂ sol/ZnO@Ag/silica sol composite exhibited stable ECL behaviors, and a sensitive and selective method was developed for VpCl determination. Under the optimal conditions, the ECL response of the sensor showed a linear correlation to the concentration of VpCl in the range of 1.0 × 10⁻⁷–1.0 × 10⁻⁴ mol L⁻¹ (<i>R</i>² = 0.9832) with a detection limit of 7.00 × 10⁻⁹ mol L⁻¹ (<i>S</i>/<i>N</i> = 3). The RSD of ECL response was 2.07 % for 1.0 × 10⁻⁵ mol L⁻¹ VpCl under 10 continuous cyclic scans. The spiked recovery was 97.90–104.50 % for determination of real VpCl sample. The proposed method exhibited selectivity and sensitivity for VpCl, and improved efficiency of Ru(bpy)₃²⁺.</p>