Study On The Electrochemiluminescent Properties Of Rhodamine B

The recent development in the fields of electrochemiluminescence (ECL), potential-resolved electrochemiluminescence were reviewed. We proposed rhodamine B ECL system based on previous reports about dye electrochemiluminescence. In this thesis, a high fluorescence yield of Rhodamine B in aqueous solution and the influence ECL behavior of Rhodamine B by thiourea and H₂O₂ on electrochemiluminescence and it's applications were studied. The main results as follows:1. In aqueous alkaline solutions, the potential-resolved electrochemi luminescent (ECL) behavior of Rhodamine B at a platinum electrode was investigated. Two sharp ECL light emission peak appeared near 0.9 V and -0.45V (vs. Ag/AgCl) under cyclic voltammogram (CV) conditions. In order to obtain a better understanding of the light emission, we investigated the effects of supporting electrolytes, the pH value, the presence of O2 or N2, and the concentration of Rhodamine B. A possible mechanism for the behavior of Rhodamine B in this system was also proposed.2. The electrochemiluminescence intensity of rhodamine B in the alkaline solution can be enhanced significantly by thiourea at -0.45V, and the enhanced luminescence intensity and thiourea showed a good linear relationship. It's speculate that caused by thiourea series of changes, ultimately resulting dimer radical cations of thiourea. RhB* was produced on the electrode surface resulting RhB- reaction, RhB* returning to ground state produce luminescence.3. The impact ECL of rhodamine B by H₂O₂ was studied in neutral aqueous solution. It's found that H₂O₂ Rhodamine B can significantly enhance the luminescence intensity at around 0.9V. When the H₂O₂ concentration was 1.0mM, the Rhodamine B emission intensity was the strongest in the 0.9V. At this point in the range of Rhodamine B concentration showed a good linear relationship. Explaining the mechanism may be due to H₂O₂ produced a large number of O2 at high potentials, the electrolysis process is accompanied by nascent oxygen [O] formation, a large number of [O] can oxidate Rhodamine B and then generated luminescence. When we add a small amount of ascorbic acid to the solution, we found that the luminescence signal of rhodamine B significantly reduced, indicating ascorbic acid consumption of the [O], so the amount of [O] reaction with Rhodamine B was decreased, then the light signal reduced.As rhodamine B is widely used fluorescent dye and the biological study based on the above, it will be very important to the determination of organic compounds and DNA.