Studies Of Electrochemical Behavior Of Metribuzine And The Interaction Between Metribuzine And DNA

Endocrine-disrupting chemicals(EDCs) have been received more and more attention for their serious effects to human and other mammals. Some kinds of pesticides are known as endocrine-disrupting chemicals, just like the metribuzine in this paper. There are many detection technology for pesticides residues including gas chromatography(GC), high performance liquid chromatography(HPLC), gas chromatography-mass spectrometry, supercritical liquid chromatography (SFC), immunosensor analytical technology, enzyme linked immuno-sorbent assay(ELISA), chemiluminescence analysis(CL), high performance liquid chromatography-mass spectrometry(HPLC/MS) ect. But these method' s determination time is longer and instruments are more expensive. Electrochemical method that can give high sensitivity and satisfactory selectivity is simple, fast and accurate. Differential-pulse voltammetry has been used to study the voltammeteric property of metribuzin at glass carbon electrode and Nafion modified electrode, which is a kind of herbside. The binding of metribuzin with calf thymus DNA has been investigated by voltammetry, UV-Vis spectra fluorescence spectrophotometry and viscosity measurements. The thesis is composed of four chapters. Chapter 1:PrefaceIn the first part of this thesis, the progress of the determination method for pesticides is reviewed. Put forward the adventage whichelectrochemistry action plays in the analyzing of pesticide residue.Chapter 2: Study and determination of metribuzin by differential-pulse stripping voltammetryMetribuzin is reduced at a glass carbon electrode bydifferential-pulse stripping voltammetry in BR buffer(pH=2. 0). The peak potential is at about -0.52V (VS. SCE) . The linear range is 1 XKT—IXKTW/L, and the detection limit is 3. OX 10~7mol/L. The voltammetric behavior and reaction mechanism have been studied. It shows that it' s an unreversible process with two electron and two proton transfered at glass carbon electrode.Chapter 3: Study and determination of metribuzin at nafion modified electrode by differential-pulse stripping voltammetryAfter modified the glass carbon electrode by nafion, metribuzin has been studied by differential-pulse stripping voltammetry at modified electrode. The linear range is 5X 10"7~7X lO^mol/L. The detection limit is 2.6X10~*mol/L, it is one quantity grade lower than at bare electrode. The determination of metribuzin of lowerconcentration has been done and the results is satisfactory. Chapter 4: Study of the interaction between metribuzin and DNA The interaction of metribuzin with calf thymus DNA has beeninvestigated by voltammetry. It has been found that adding DNA to the solution of metribuzin cause decreasing of peak currents. The binding mode has also been studied with the assistance of UV-Vis spectra fluorescence spectrophotometry and viscosity measurements. It shows that metribuzin binds with DNA probably by intercalation.