Determination Of Hypochlorite, Adenine And Ascorbic Acid By Fluorescence Spectrophotometry

Recently, growing concern has been paid to environment, health, pharmaceutical because of its crucial roles in our daily life. Therefore, it was necessary to perform a simple, sensitive and rapid method for determination of hypochlorite, adenine, and ascorbic acid from environment pollution, DNA and drug respectively. In this work, the hypochlorite, adenine, ascorbic acid were selected as the study objects. The redoxreaction between hypochlorite and Nile blue A in the solution of surfactant, interactions of L-tryptophan- Cu2+ complex and adnine, thiamine-K3[Fe(CN)6] and ascorbic acid were researched. The optimal conditions, mechanism of reactions, fluorescence quenching and enhancement, the spectral properties of fluorescence and absorption also were investigated. Accordingly, a novel spectrofluorometry method for detection of hypochlorite, adenine, and ascorbic acid has been established. Additionally, the method was successful applied for detect in real samples with satisfied. The main work of contents was as followed: 1. A selective fluorescence quenching method for the determination of trace hypochlorite in water samples with Nile Blue ARecently, growing concern has been paid to the sensitive and selective determination hypochlorite because of its crucial roles in our daily life. In this paper, a simple, sensitive, selective spectrofluorimetric method was applied to detect the hypochlorite. Upon reaction of the probe with ClO-, a fluorescence quenching was observed. The method was shown to be highly selective for ClO-, and exhibited real time response as well as linear relationship to ClOconcentration, and hypochlorite could be detected at low micromolar levels in aqueous solution. The linear response range of hypochlorite(R2=0.9994) was from 0.13 to 25 μmol L-1. The detection limit(3σ/k) was 0.04 μmol L-1, which lower than that of previous mentioned. The accuracy and reliability of the method was further ensured by recovery studies via a standard-addition method, with percentage recoveries in the ranges of 95.0% to 104.8%, 96.3% to 102.6% and 97.8% to 102.5, respectively. Additionally, the quenching mechanism was discussed. Judging from temperature, fluorescence lifetime, UV-visible absorbance spectra, quenching mechanism was proved static quenching. This method was finally used to detect the hypochlorite in local water samples. 2. Determination of adenine based on the fluorescence recovery of the L-tryptophan- Cu2+ complexA simple and sensitive method for determination of adenine was developed based on fluorescence quenching and recovery of L-Tryptophan(L-Trp). The fluorescence of L-Trp could efficiently quenched by copper ion compared with other common metal ions. Upon addition of adenine(Ade) in L-Trp- Cu(Ⅱ) system, the fluorescence was reoccurred. Under the optimum conditions, the recovery fluorescence intensity was linearly correlated with the concentration of adenine in the range from(0.34-25.0) μmol L-1, with a correlation coefficient(R2) of 0.9994. The detection limit(3σ/k) was 0.046 μmol L-1, indicating that this method could applied to detect trace adenine. In this study, amino acids including L-Trp, D-Trp, L-Tyr, D-Tyr, L-Phe, D-Phe were investigated and only L-Trp could well chelated copper ion. Additionally, the mechanism of quench and recovery also were discussed and the method was successfully applied to detect the adenine in DNA with satisfactory results. 3. A novel spectrofluorometry method for determination of ascorbic acid utilizing thiamine- K3[Fe(CN)6] systema simple and sensitive spectrofluorometry method for detection of ascorbic acid was performed. In alkaline medium, the non fluorescent thiamine could be oxidized by K3[Fe(CN)6] and formed the blue fluorescent thiochrome with an excitation peak of 367 nm and an emission peak of 441 nm. However, the fluorescence intensity gradually decreased with adding ascorbic acid in system. Under the optimum conditions, the decreased fluorescence intensity was linearly correlated with the concentration of ascorbic acid in the range from(0.086- 1.5) μmol L-1, with a correlation coefficient(R2) of 0.9996. The detection limit was 0.026 μmol L-1, which was lower than many other methods. Additionally, the mechanism of enhance and quenching were discussed and the method was used to detect the ascorbic acid in actual samples with satisfying results.