Efficient Electrogenerated Chemiluminescence of Tris(2,2'-bipyridine)ruthenium(II) with N-Hydroxysulfosuccinimide as a Coreactant for Selective and Sensitive Detection of l-Proline and Mercury(II).

Developing rapid, specific, and low-cost electrogenerated chemiluminescence (ECL) systems remains a compelling goal for many applications including environmental analysis, clinical diagnostics, and food safety. In this study, N-hydroxysuccinimide (NHS) esters, especially N-hydroxysulfosuccinimide (NHSS), was exploited for the first time as an efficient coreactant for anodic Ru(bpy)32+ ECL in neutral medium. Among the three tested NHS esters (NHS, NHSS, NHPI), the NHSS exhibited much higher ECL intensity and stability than the sulfonate-free esters, suggesting the essential role of both the N-hydroxy (NOH) and sulfonate (SO3H) moieties in the developed Ru(bpy)32+ ECL system. The ECL generation process is rather straightforward, not requiring time-consuming fabrication/modification steps of electrodes. The anodic Ru(bpy)32+-NHSS system achieved ECL detections with high selectivity and sensitivity toward l-proline (LOD = 50 nM) and Hg2+ (LOD = 10 nM), with a linear range of 0.5-200 μM and 0.1-25 μM, respectively. The method showed good recoveries (95.2-104.8%) for l-proline and Hg2+ detection in real samples. This study is a successful step toward the development of new coreactants and may open new avenues for the applications of N-hydroxy compounds in ECL sensing.