Sensitive and selective determination of GSH based on the ECL quenching of Ru(II) 1,10-phenanthroline-5,6-dione complex

Electrochemiluminescence (ECL) material Ru-dpq (Ru(bpy)2dpq(2+), dpq=1,10-phenanthroline-5,6-dione; bpy=2,2'-bipyridine) is found to be produced strong and stable anodic ECL signal, which could be quenched by reduced glutathione (GSH) and exhibits high sensitivity and selectivity simultaneously. According to the mass spectra of Ru-SG (product of Ru-dpq reacted with GSH), and single crystal structure of the final oxidized product Ru-dcbpy ((Ru(bpy)2dcbpy(2+), dcbpy=3,3-dicarboxy-2,2-bipyridine), we propose a new interacted mechanism between Ru-dpq and GSH. A good linear relation is estimated to be from 0.1 pM to 50 μM in the presence of calcium ion and the detection limit is as low as 0.087 pM (with the signal-to-noise ratio of 3). The relative standard deviation is 2.3% (for three repeated measurements). Furthermore, the ECL signal of Ru-dpq under a constant potential (1.2V) is extremely stable and the intensity could be maintained over 600 s, which promotes us to determine the concentration of GSH via chronoamperometry.