| Flow injection chemiluminescence(FI-CL) has made great progresses in analytical chemistry for its high sensitivity, wide linear dynamic range, rapidity, simplicity, and being appropriate for on-line analysis. It has been successfully applied in different fields such as environmental monitoring, drug analysis, clinical testing and antioxidant analysis research.This thesis focused on the new applications of FI-CL and anti-oxidantion research of some compounds. The contents consist of the following four parts:Part I Determination of hydroxyurea using an inhibitory FI-CL methodHydroxyurea is an anti-neoplastic. It can inhibit ribonucleoside reductase and DNA replication. This study found that hydroxyurea can significantly inhibit the chemiluminescence which generated by luminol and pyrogallol in alkaline solutions. Accordingly, a novel flow-injection chemiluminescence method for the determination of hydroxyurea was developed. Under the optimum conditions, the inhibitory rate(Y)was linear with the concentration of hydroxyurea(C) in the range of 5×10-6-5×10-4 mol/l, the regression equation was Y = 42.84lgC (μmol/l)+ 229.7 (r=0.9980). A detection limit of 5.1×10-7 mol/l, along with relative standard deviation of 0.63% (n=11) for 5×10-6 mol/l hydroxyurea, were obtained respectively. This method not only can be used for the determination of hydroxyurea in medicament, but also expects to be applied in other clinical and medical researches associated with hydroxyurea.Part II Determination of hydrazine using an enhanced FI-CL/ SI-CL methodAs the the raw materials of various polymers, pesticides, chemical products and drugs, hydrazine is widely used in industry, agriculture, explosives and other fields. Meanwhile, it has been identified as mutagens and animal carcinogens. Therefore, it is very important to establish a sensitive method for determing hydrazine in environmental samples. In this paper, highly sensitive FI-CL and sequence-injection chemiluminescence (SI-CL) methods for the determination of trace amount hydrazine in water have been developed. The procedure was based on the chemiluminescent reaction of luminol with hydrogen peroxide in alkaline solution, where hydrazine acted as a catalyst and strongly enhanced the CL intensity. Under the optimum condition, when utilizing the FI-CL method, the CL intensity was linear with the concentration of hydrazine in the range of 1.6×10-8-1.6×10-4 mol/l, the regression equation wasΔI=0.8225C (mol/l) + 8.086 (r=0.9954). A detection limit of 5.1×10-9 mol/l, along with relative standard deviation of 5.4% and 0.82% (n=11) for 1.6×10-8 mol/l and 1.6×10-6 mol/l hydrazine, were obtained respectively. An ion-exchange column combined in the system could remove the interferences of foreign ions potentially coexisting in water. The method was simple, rapid, and has been successfully applied in the determination of hydrazine in water with recoveries of 85.4%- 99.5%. For SI-CL method, CL intensity was linear with theconcentration of hydrazine in the range of 3.2×10-10-3.2×10-4 mol/l. A detection limit of 6.7×10-11 mol/l, along with relative standard deviation of 3.14% (n=11) for 3.2×10-8 mol/l hydrazine, were obtained respectively. Compared with other chemiluminescence methods for hydrazine, the present one possesses better performance for its wide linear dynamic range, rapidity and simplicity. These properties make the method play a role in online monitoring of trace hydrazine in the environmental samples and evaluating the efficiency of hydrazine decomposition catalysts.Part III A sequential injection electrochemiluminescence method for studying the anti-oxidative properties of tea polyphenolsTea polyphenols is a class of favorable nature antioxidant. In this paper, a novel sequential-injection electrochemiluminescence system for studying the anti-oxidative properties of tea polyphenols has been established. Under the optimal conditions, the IC50 of tea polyphenols was 13μg/ml, the inhibitory rate (Y) was linear with the concentration of tea polyphenols(C) in the range of 2.5 - 25μg/ml, regression equation was Y = 2.774C (μg/ml) + 10.06 (r=0.9909). The results provide a new technique for evaluating the antioxidants.Part IV Study on the antioxidant activity of chitooligosaccharides (COS) by SI-ECL/ FI-CL methodChitooligosaccharides (COS) is derivative of chitosan and can be prepared by either chemical or enzymatic hydrolysis of chitosan. Compared with chitosan, COS possess additional functional properties such as antifungal, antimicrobial, antitumor, immuno-enhancing, and weight-losing effects. Moreover, they have lower viscosities, lower molecular weights, shorter chain lengths and better water-solubility. These characteristics make COS get increasing attention in various fields, especially in the functional food and medicine industries. In the present study, the aforementioned FI-CL and SI-ECL systems were used for anti-oxidative research of COS, emphasised on the determination of the scavenging ability on superoxide anion, hydroxide radical, hydrogen peroxide and lipid hydroperoxides. The results not only showed that the established systems possess extensive applicability in antioxidive research, but also confirmed that COS is a long-acting natural antioxidant comparing with Vc and tea polyphenols. |
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