A novel solid-state electrochemiluminescence detector for capillary electrophoresis based on tris(2,2′-bipyridyl)ruthenium(II) immobilized in Nafion/PTC-NH2 composite film

A new electrochemiluminescence (ECL) detector for capillary electrophoresis (CE) based on tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) immobilized in Nafion/PTC-NH2 (an ammonolysis product of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)) composite film was presented for the first time. The Nafion/PTC-NH2 composite film could effectively immobilize tris(2,2′-bipyridyl)ruthenium(II) via ion-exchange and electrostatic interaction. Cyclic voltammetric and ECL behavior of Nafion/PTC-NH2/Ru composite film was investigated compared to Nafion/Ru composite. The Nafion/PTC-NH2/Ru composite film exhibited good ECL stability and simple operability. Then the CE with solid-state ECL detector system was successfully used to detect sophora - a quinolizidine type - alkaloids as sophoridine (SR) and matrine (MT). The CE-ECL parameters that affected separation and detection were optimized. Under the optimized conditions, the linear range was from 2.5 × 10−8 to 2 × 10−6 mol/L for SR, 1.0 × 10−8 to 1.0 × 10−6 mol/L for MT. The detection limit (S/N = 3) was estimated to be 5 × 10−9 and 10−9 mol/L for SR and MT, respectively. It was shown that the CE coupling with solid-state ECL detector system exhibited satisfying sensitivity of analysis.