Investigation On Luminol Chemiluminescence Catalyzed By Nanoparticles Containing Cobalt Or Iron And Analytical Applications

Chemilumineseence (CL) analysis method has been applied in kinds of fields owing to its advantages such as simple instrument, no additional light source, high sensitivity and wide calibration range. In recent years, CL has been expanded with the development of nanotechnology and nanoparticles. In this dissertation, the history of CL, the research and application of nanoparticles in CL and the latest developments were review. And in the present work, nanoparticles containing cobalt or iron were chosen as catalysts for the luminol system and the application were investigated. The research work contained the following main aspects:1. It was found that Fe3O4 magnetic nanoparticles (Fe3O4 MNPs), as a kind of mimetic enzyme of peroxidase, could catalyze the CL reaction of luminol and H2O2. And the CL system of luminol-H2O2-Fe3O4 MNPs was established combined with the flow injection technique for H2O2. The optimum reaction conditions and the effects of pH and temperature on the mimetic enzyme Fe3O4 MNPs were investigated. The linear range for H2O2 was 1.0×10-7～1.0×10-5 mol/L with a detection limit of 2.9×10-8 mol/L. The selectivity of the proposed method was evaluated. Finally, the possible mechanism was proposed. The proposed method was used to H2O2 determination in rainwater samples with satisfactory results.2. It was found that CoFe2O4 magnetic nanoparticles (CoFe2O4 MNPs) could catalyze the CL reaction of alkaline luminol and dissolved oxygen. On the basis of investigations of the kinetic characteristics curves, the CL spectrum and the UV-vis spectrum of the CL system, the possible catalytic mechanism was proposed. Two points are concerned on the practical applications of the studied CL system as follows:(1) Some reducing organic compounds mainly containing -NH2 and -OH were observed to inhibit the CL signal of the luminol-O2-CoFe2O4 MNPs reaction, in which the inhibition of catechol to the CL system was most intense. Thus, catechol was chosen as a model compound to demonstrate the analytical application of the proposed CL system combined with the flow injection analysis. The inhibitory kinetic characters of catechol with different concentrations in the CL system were studied and the optimum experimental conditions were established. Under the optimal conditions, the inhibitory CL intensity and the logarithm of the catechol concentration was linear in the range of 5.0×10-10～1.0×10-7 g/mL and the limit of detection low to 6.4×10-11 g/mL. The proposed method was employed to determine catechol in synthetic water samples, and the recoveries of catechol of different concentrations in the spiked water samples were from 84% to 105%.(2) The CL intensity of luminol-O2-CoFe2O4 MNPs reaction was decreased significantly when nitrite was introduced into the CL system. The inhibitory kinetic character curves were investigated with the flow injection analysis. Under the optimum conditions, the inhibitory CL intensity and the negative logarithm of the nitrite concentration was linear in the range of 2.0×10-7～1.0×10-3 mol/L with the detection limit of 7.9×10-8 mol/L. The proposed method was used to determine nitrite in water samples, and the recoveries of nitrite in the spiked water samples were from 90% to 103%.3. The supported Co/SiO2 nanoparticles could be served as a kind of new catalysis for the luminol-H2O2 CL reaction and the CL intensity was enhanced remarkably. On this basis, we conducted the following works.(1) The kinetic characteristics curves, the CL spectrum and the UV-vis spectrum of the luminol-H2O2 CL system in the present of supported Co/SiO2 nanoparticles were investigated. And then the CL system of luminol-H2O2-supported Co/SiO2 nanoparticles was explored for H2O2 analysis. Under the optimum experimental conditions, the CL intensity and the concentration of H2O2 was linear in the range of 3.0×10-9～5.0×10-6 mol/L with the detection limit of 1.1×10-9 mol/L. The proposed method was used for H2O2 concentration in rain water samples and the recoveries were between 89% and 105%.(2) A new chemiluminescence method was developed for ascorbic acid based its inhibition effect on strong chemiluminescence emission produced from luminol-H2O2-supported Co/SiO2 system. Under optimum conditions, the linear range for ascorbic acid was 4.0×10-9-1.0×10-7 g/mL with a detection limit of 4.2×10-10 g/mL. The proposed method has been successfully applied to the determination of ascorbic acid in tables with satisfactory results.