Electrochemiluminescence determination of codeine or morphine with an organically modified silicate film immobilizing Ru(bpy) 3 2+

An ECL approach was developed for the determination of codeine or morphine based on tris(2,2′‐bipyridine)ruthenium(II) (Ru(bpy) 3 2+ ) immobilized in organically modified silicates (ORMOSILs). Tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMe‐DiMOS) were selected as co‐precursors for ORMOSILs, which were then immobilized on a surface of glassy carbon electrode (GCE) by a dip‐coating process. Ru(bpy) 3 2+ was immobilized in the ORMOSIL film via ion‐association with poly( p ‐styrenesulphonate). The ORMOSIL‐modified GCE presented good electrochemical and photochemical activities. In a flow system, the eluted codeine or morphine was oxidized on the modified GCE and reacted with immobilized Ru(bpy) 3 2+ at a potential of +1.20 V (vs. Ag/AgCl). The modified electrode was used for the ECL determination of codeine or morphine and showed high sensitivity. The calibration curves were linear in the range 2 × 10 −8 –5 × 10 −5 mol/L for codeine and 1 × 10 −7 –3 × 10 −4 mol/L for morphine. The detection limit was 5 × 10 −9 mol/L for codeine and 3 × 10 −8 mol/L for morphine, at signal:noise ratio (S:N) = 3. Both codeine and morphine showed reproducibility with RSD values <2.5% at 1.0 × 10 −6 mol/L. Furthermore, the modified electrode immobilized Ru(bpy) 3 2+ was applied to the ECL determination of codeine or morphine in incitant samples. Copyright © 2007 John Wiley & Sons, Ltd.