Electrogenerated Chemiluminescence of Tris(2,2′-bipyridyl)ruthenium(II) Immobilized in Humic Acid-Silica-Poly(vinyl alcohol) Composite Films

Abstract In this paper, we report the first attempt to use humic acid (HA) as modifiers to prepare the organic‐inorganic hybrid modified glassy carbon electrodes based on HA‐silica‐PVA (poly(vinyl alcohol)) sol‐gel composite. Electroactive species of tris(2,2′‐bipyridyl)ruthenium(II) (Ru(bpy) $\rm{ {_{3}^{2+}}}$ ) can easily incorporate into the HA‐silica‐PVA films to form Ru(bpy) $\rm{ {_{3}^{2+}}}$ modified electrodes. The amount of Ru(bpy) $\rm{ {_{3}^{2+}}}$ incorporated in the composite films strongly depends on the amount of HA in the hybrid sol. Electrochemical and electrogenerated chemiluminescence (ECL) of Ru(bpy) $\rm{ {_{3}^{2+}}}$ immobilized in HA‐silica composite films coated on a glassy carbon electrode have been studied with tripropylamine (TPA) as the coreactant. The analytical performance of this modified electrode was evaluated in a flow injection analysis (FIA) system with a homemade flow cell. The as‐prepared electrode showed good stability and high sensitivity. The detection limits ( S / N =3) were 0.050 μmol L −1 for TPA and 0.20 μmol L −1 for oxalate, and the linear ranges were from 0.10 μmol L −1 to 1.0 mmol L −1 for TPA and from 1.0 μmol L −1 to 1.0 mmol L −1 for oxalate, respectively. The resulting electrodes were stable over two months.