| Chemiluminescence (CL) is a powerful analytical technique that has high sensitivity, wide linear range, and requires relatively simple and inexpensive instrumentation. It has been exploited in a wide range of applications in different fields, such as chemistry, biology and environmental chemistry. The association of instantaneousness of the CL with short life-time of reactive oxygen species (ROS) radicals has a potential research prospect. Peroxymonocarbonate ion (HCO4-) is a highly reactive oxidant, and chemiluminescence can arise from its decomposition. In this work, we studied the chemiluminescent mechanism of peroxymonocarbonate decomposition and its reaction with nanoparticles. Moreover, the analytical applications of these new HCO4- CL systems were investigated. The contents were summarized as follows: 1. The concept of chemiluminescence, the kinds, formation and detection method of ROS, and the production, significance and application of chemiluminescence about peroxide, including hydrogen peroxide, peroxynitrite acid, peroxymonosulfate and peroxymonocarbonate are reviewed. Applications of nanoparticles in chemiluminescent system, especially the quantum dots (QDs) are focused.2. Quantum dots has attracted much attention due to the unique size-dependent optical and electronic properties, and has been widely used in recent years. In alkaline medium, bicarbonate reacts with hydrogen peroxide to form peroxymonocarbonate ion (HCO4-), which is an unstable compound. During the decomposition of HCO4-, a weak CL was observed. A series of aqueous colloidal CdTe QDs capped with mercaptoacetic acid were synthesized and applied to the hydrogen peroxide-sodium hydrogen carbonate CL system. The CL emission intensity was significantly enhanced by different sizes of CdTe QDs. The effects of pH, concentrations and particle size of QDs on CL intensity have been investigated. The mechanism was discussed based on the CL emission spectra, electron spin resonance (ESR) spectra, UV-Vis absorption spectra and fluorescence spectra.3. Quantum dots prepared at normal conditions often has many surface traps. The surface structure of QDs plays a key role in determining the properties of the particles. Unpassivated surface atoms can form electronic traps for electrons and holes that affect their optical and electronic properties. Thus, it is very important to passivate the surface traps of QDs in order to obtain a highly efficient luminescence with a narrow emission line width. This passivation can be acccomplished by capping the particle surface with an organic agent or shell of a larger band gap semiconductor. Core-shell structure quantum dots of CdSe/CdS QDs capped with mercaptoacetic acid was synthesized in aqueous solution. It was applied in the hydrogen peroxide-sodium hydrogen carbonate CL system. Effect of different physicochemical parameter on the CL emission was investigated and the CL mechanism was discussed. Superoxide ion radical (·O2-) and hydroxide radical (·OH) were generated during the reaction of NaHCO3 and H2O2, which were the key intermediates for the production of hole, electron-injected CdSe/CdS QDs and the CL emission. L-ascorbic acid can inhibit this enhanced CL signal, and the CL intensity is dependent on L-ascorbic acid concentration. Based on this phenomenon, a new, simple, sensitive and selective flow injection analysis method is proposed for the determination of L-ascorbic acid. It has been successfully used to detect L-ascorbic acid in human serum with satisfactory results compared with other reported method.4. Carbon micro-and nanospheres are a kind of spherical carbon materials. They have good chemical stability and thermal stability, and high electric conductivity and thermal conductivity. Nanostructured spherical carbon materials have become an interesting research object for many researchers in recent years owing to their broad prospect of applications. Carbon nanospheres prepared by hydrothermal synthesis from glucose has good monodispersity. Due to the unique surface properties, carbon nanospheres can be coated with noble-metal nanoparticles, oxide nanoparticles, or semiconductor quantum dots to obtain specific catalytic, magnetic, electronic, optical, or optoelectronic properties. In this work, carbon nanospheres have been prepared from aqueous glucose solution by hydrothermal synthesis. The structure and surface functional groups of carbon nanospheres were characterized. A significant enhancing effect was obtained in NaHCO3-H2O2-carbon nanospheres CL system. The possible mechanism of reaction was discussed. The new chemiluminescence system with NaHCO3-H2O2 and carbon nanospheres as reagents was optimized and applied to detect hydrogen peroxide in tap water and snow water by flow injection analysis method. Experimental results compared with other CL system, showed that it was a sensitive and selective method for hydrogen peroxide detection.5. Potassium permanganate is a strong oxidant. Very sensitive CL emission can be generated by potassium permanganate in acidic medium. We studied the chemiluminescent mechanism of HCO3--H2O2 CL system in the presence of potassium permanganate. Our purpose is to investigate the formation and decomposition mechanism of HCO4- existing in high oxidant solution, and simultaneously to improve the CL mechanism of KMnO4 in alkaline medium. We found the CL intensity of HCO3--H2O2 system was significantly enhanced when potassium permanganate was added. Effects of different surfactant and radical scavengers contributed to the understanding of the NaHCO3-H2O2-KMnO4 CL system mechanism. The mechanism involving oxygen and carbon dioxide dimmer was proposed. The CL spectrum for NaHCO3-H2O2-KMnO4 system showed two peak bands at 440 nm and 634 nm, respectively. Energy-transfer process existed between NaHCO3-H2O2-KMnO4 system and rhodamine B or uranine based on fluorescence spectra, UV-Vis absorption spectra and CL spectra.
|
PDF Full Text Request