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) 3 2+ 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 (SO 3 H) moieties in the developed Ru(bpy) 3 2+ ECL system. The ECL generation process is rather straightforward, not requiring time-consuming fabrication/modification steps of electrodes. The anodic Ru(bpy) 3 2+ –NHSS system achieved ECL detections with high selectivity and sensitivity toward l -proline (LOD = 50 nM) and Hg 2+ (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 Hg 2+ 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.