Development of Ru(bpy)₃ ²⁺-amisulpride electrogenerated chemiluminescence system for ultrasensitive and selective detection of amisulpride in pharmaceuticals and real plasma

In this study, a new electrogenerated chemiluminescence (ECL) reaction is presented through an oxidative-reductive pathway for amisulpride (AMS) as a new coreactant and Ru(bpy)₃ ²⁺ luminophore for the first time. The unique chemical structure of AMS through the presence of electroactive tertiary amino group in combination with the presence bulky electron donating group attached to α‑carbon of its amino group demonstrates the dramatic increase in ECL intensity of luminophore. Upon electrochemical oxidation of both the AMS and Ru(bpy)₃ ²⁺, the electrogenerated AMS⁺ undergoes spontaneous deprotonation to produce strong reductant that is reacted with electrogenerated Ru(bpy)₃ ³⁺ for excited state production. The developed method presented highly sensitive, selective, rapid, simple and cost-effective ECL approach for AMS detection. Under optimized parameters, the ECL-concentration plot showed a good linear relationship between ECL intensity and AMS concentrations in presence of 1.0 mM Ru(bpy)₃ ²⁺ over the concentration range of (5.0 × 10⁻¹⁰–2.0 × 10⁻⁷ M) with a lower detection limit of 7.6 × 10⁻⁹ M and a lower quantification limit of 2.51 × 10⁻⁸ M. The developed ECL method is successfully utilized for the determination of AMS in Amipride tablets and real human plasma.