Facile nano-free electrochemiluminescence biosensor for detection of sulphamethoxazole via tris(2,2'-bipyridyl)ruthenium(II) and N-methyl pyrrolidone recognition

The electrochemiluminescence (ECL) system based on the ruthenium complex has become a powerful tool in the field of analytical chemistry. However, the non-aqueous ECL luminescence system, which does not involve complex nano-modification, has not been widely used for the determination of analytes. In this study, N-methyl pyrrolidone was selected as the solvent, and it could also act as a co-reactant of [inline-formula removed]. Based on this, a simple ECL system without nanomaterials was established. Strong ECL was generated. Furthermore, a quenching effect between the excited state of [inline-formula removed] and sulphamethoxazole (SMZ) was observed. Based on this, a sensitive ECL sensor for detecting SMZ is constructed. A linear relationship between ECL signal quenching intensity (ΔI) and the logarithm of SMZ concentration (log C) in the concentration range of 1 × 10^-7-1 × 10^-5 mol/l is obtained. The limit of detection is as low as 3.33 × 10^-9 mol/l. The method has been applied to the detection of SMZ in tap water samples with different concentration levels with satisfactory results, and the recovery was 95.3-102.6%.

Detection of 1,3-dihydroxyacetone by tris(2,2'-bipyridine)ruthenium(II) electrochemiluminescence

1,3-Dihydroxyacetone, a common cosmetic material and food additive, has been successfully explored as an efficient electrochemiluminescence coreactant of Ru(bpy)₃²⁺ for the first time. It is about 25 times more effective than the well-known coreactant sodium oxalate. The high electrochemiluminescence efficiency allows sensitive detection of 1,3-dihydroxyacetone without any derivatization. The electrochemiluminescence method shows two linear electrochemiluminescence responses over the range of 5.0-500 μM and 500 μM-6.0 mM with a detection limit of 1.79 μM. The proposed method is at least two orders of magnitude more sensitive than other reported methods. Graphical abstract ECL intensity-potential profile of 1,3-dihydroxyacetone (DHA) and oxalate.