Detection of malachite green and leucomalachite green based on electrochemiluminescence of mono- and bimetallic ruthenium tris-bipyridyl complexes at an Au electrode

Electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) and bimetallic ruthenium tris-bipyridyl complex [(bpy)(2)Ru(bpy)(CH2)(8)(bpy)Ru(bpy)(2)](4+) (1) at a gold electrode has been employed for the determination of malachite green (MG) in this paper. For Ru(bpy)(3)(2+), a linear response (R-2 = 0.9992) was obtained over a MG concentration range of 1.0 x 10(-8) to 1.0 x 10(-5) M, with a remarkable detection limit of 1.0 x 10(-8) M in a pH 10 borate buffer. The detection limit was further decreased to 1.0 x 10(-12) M for the bimetallic ruthenium complex 1. Meanwhile, leucomalachite green (LMG) was detected and the same detection limit was reached. Which is much lower compared to the other detection methods. To check its applicability, the proposed method was employed in the determination of MG/LMG added into a fishpond water sample, and good reproducibility and stability were achieved. These results show that it will be possible to develop an ECL detection method for MG/LMG.