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New method research of chemiluminescence analysis

Chemiluminescence research of carbon and oxygen, nitrogen and oxygen, sulfur and oxygen and other reactive oxide   

        The oxidation reaction is a very important reaction in the chemical reactions, the O-O bond cleavage oxygen transfer plays an important role in organic chemistry. The process was considerd as the most likely mechanism of oxidation in biological systems. Even if the oxide oxygen atom transfer mechanism is not understood, but it is well-known that some oxidizing reagents, such as hydrogen peroxide (HOOH), peroxy nitrate (HOONO2), peroxy carbonate (HOOCO2-), the peroxygen sulfate (HOOSO3-) and an organic hydroperoxide, all belong to this oxidation reaction. Aerobic transfer involved in an oxidation reaction, hydrogen peroxide and its isomers are often regarded as a reaction intermediate product, their activity is given considerable attention. 

        Oxidizing reagent, such as HOOH, HOONO2, HOOCO2-, and HOOSO3-, their chemical activity is mainly reflected in the aqueous solution, particularly the solvent effect has a great influence on their stability in the peroxide. Over the past decade, two theories of solvent effect have been developed: continuous model and the discrete solvent model. Solute molecules in a continuous model is assumed to be in a hole, the solvent effect is regarded as the solute molecules are distributed in a dielectric medium having a uniform nature. In a discrete model, the solvent is considered to be molecules, considering the interaction of the solvent molecules and solute, because this effect is often derived contributions by many different configurations of the weakly interacting entangled body.

        Our research group has been engaged in the active oxygen, carbon and oxygen reactive oxides, nitrogen and reactive oxides, sulfur and oxygen activity oxide and hydrogen peroxide chemiluminescence, a series of practical value chemiluminescence reaction system were established.

Preparation and Chemiluminescence behavior of Fluorescent Carbon Quantum Dots   

        Carbon dots with fluorescence (FL) are an exciting new class of carbonaceous nanoparticles with higher photoactivity, lower toxicity and cheaper cost compared with heavy-metal containing quantum dots. Carbon dots were prepared by facile and economic microwave treatment with serine as the carbon source, PEG 1500 and glycerine as the co-reactant. The microwave treatment firstly caused the dehydration and pyrolysis of the source materials, and then made them broken into small luminescent carbon dots. The emission shifts as the excitation wavelength increases, which indicates a distribution of the different surface energy traps of the carbon dots. The quantum yield (λex = 360 nm) for the carbon dots is 12%, obtained by using quinine sulfate as the reference. Fluorescent carbon dots were first demonstrated to have the ability of CL in the presence of ONOOH, which was formed by online mixing of acidified H2O2 and NaNO2. A linear relationship between the nitrite for the formation of ONOOH and the CL signal produced from the carbon dots-NaNO2-H2O2 system was found. It can be concluded that carbon dots are the main emitters in the CL system. The CL mechanism of the carbon dots-NaNO2-H2O2 system can be mainly explained by radiative electron-hole annihilation between hole-injected and electron-injected carbon dots (R.+ and R.-). With the advantage of the CL of carbon dots in the presence ofONOOH, we have developed a sensitive, simple, and straightforward flow-injection CL method for nitrite. The established method has been successfully applied to the determination of nitrite in pond water, river water, and milk with good recovery and high reproducibility. The research results were published in Anal. Chem. and Chem. Commun.