Electrochemiluminescence of Ru(bpy)₃²⁺/Oxamic Hydrazide and its Application for Selective Detection of 4-Nitrobenzaldehyde

Oxamic hydrazide (OHA) was utilized as an efficient coreactant of Ru(bpy)₃²⁺ for the first time, which can dramatically increase the electrochemiluminescence (ECL) intensity of Ru(bpy)₃²⁺ on glassy carbon electrode (GCE). 4-nitrobenzaldehyde (4-NBA), a nitroaromatic compound, has mutagenic and carcinogenic toxicity on humans′ genome and causes a serious impact on the environment. Hence, the detection of its level in biological and environmental samples is of great significance. Interestingly, 4-NBA was found to induce a dramatic quenching for the ECL intensity of the developed Ru(bpy)₃²⁺/OHA system owing to the formation of hydrazone product through the nucleophilic addition reaction with OHA. Under optimal conditions, the ECL decreasing value of Ru(bpy)₃²⁺/OHA in the presence of 4-NBA is linear in the range of 20 μM to 800 μM with a limit of detection (LOD) of 1.09 μM (signal-to-noise 3 : 1). Finally, this strategy enabled the detection of 4-NBA in tap water with satisfactory recoveries from 97.84 % to 103.56 %.