Investigation On Determination Methods Of Several Environmental Contaminants Based On The Nano-materials Modified Electrodes

In the present thesis, we deploy a series of works on the preparation of nano-material modified electrodes and their electrochemical detection toward organophosphates compounds and heavy metal ions. More sensitive, simple and accurate quantitative analysis method for detecting organophosphates compounds and heavy metal ions have been established. The main context of this thesis involves four parts, which are summarized as follows:1. The nano-gold/MWNT modified electrode was fabricated through electrodepositing the nanogold particles on the MWNT modified glassy carbon electrodes. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to investigate electrochemica1 behavior of methyl parathion at the modified electrode. The effects of different facts on the reduction peak current of methyl parathion were discussed, which included the amount of modified MWNT and pH of the supporting electrolyte solution. Under the optimal experimental conditions, the reduction peak currents were linearly dependent on the concentration of methyl parathion from 2.0 to 240.0μg/L, with a LOD of 1.0μg/L. The proposed method was used to detect methyl parathion in the actual samples and satisfactory results were obtained.2. The lead film/MWNT modified electrode was used for the determination of As(III) by simultaneity plating lead on the Multi-wall carbon nanotubes modified glassy carbon electrodes. CV and DPV experiments were carried out for investigating electrochemica1 behavior of As(III) on the lead film/Multi-wall carbon nanotubes modified glassy carbon electrodes. Experimental conditions such as the supporting electrolytes, deposition potential and deposition time were optimized. In order to obtain more sensitivity, square wave voltammetry (SWV) was used for detection of As(III). Under the optimal experimental conditions, SWV peak currents is relationship linearly to the concentration of As(III) from 2.0 to 450.0 ng/L, with a LOD 1.5 ng/L. The proposed method was simple, rapid and good reproducible.3. In the supporting electrolyte of HCl and KCl, the Sb(III) was detected directly using the multi-wall carbon nanotubes modified glassy carbon electrodes (MWNT/GCE). Electrochemica1 behaviors of Sb(III) at MWNT/GCE were investigated by voltammetry. Experimental conditions were optimized, which included the amount of the modified MWNT, deposition potential, the supporting electrolytes and deposition time. Under the optimal experimental conditions, a calibration plot with a wide linear range from 40 to 260μg/L was achieved with a detection limit (S/N=3) of 3.7μg/L, and the mothod has good anti-interference.4. The nanogold modified electrode was fabricated through electrodepositing the nanogold particles on the glassy carbon electrode. Then, the Oligo-nucleotide T4 (thymine) with the thiol anchor group (–SH) were self-assembled on the gold nanoparticles. Using the special interfaction of thymine to Hg²⁺ (T-Hg²⁺-T), the modified electrode for selective response to Hg²⁺ was fabricated. CV and DPV experiments were used to investigate electrochemica1 behavior of Hg²⁺ on the modified electrode. Under the optimal experimental conditions, there is a good relationship linearly between DPV peak currents and the concentration of Hg²⁺ from 1 pmol/L to 10 nmol/L, with a LOD 0.4 pmol/L. The proposed modified electrode effectively minimized the interference from coexisting heavy metal ions without the need of any masking reagents. The present technique shows high sensitivity and high selectivity.