| Electrochemical method is one of the most favorable techniques for the determination of heavy metal ions, because of its low eost, easy operation, high sensitivity and the ability of analyzing element speciation. In previous works, most study commonly combined with mercury film electrodes. However, due to the dramatic toxicity of mercury, numerous attempts have been made to replace it with new mercury-free and reliable electrode. Bismuth electrodes have been successfully used in anodic stripping analysis since2000due to their stripping behaviors similar to those of mercury electrodes and the environmentally friendly nature of bismuth. Such electrodes display high sensitivity, well-defined and reproducible response, good resolution, large cathodic potential range and insensitivity to dissolved oxygen. A new promising type of metal-film electrode, the antimony-film electrode (SbFE), has been reported and has been claimed to perform on a par with MFEs and BiFEs in ASV. Also, there are many other chemically modified electrodes, such as complex film modified electrodes and doping carbon paste electrodes. We fabricated some chemically modified electrodes to detecte metal ions and small biomolecules. The main researches are as follows:1. Study on bismuth-antimony film electrode and its application for determination of cadmium(Ⅱ)A bismuth-antimony film electrode was prepared in situ on a glassy carbon electrode and employed in combination with square wave anodic stripping voltammetry in hydrochloric acid solution (pH2.0). Under the optimum conditions, the sensor revealed highly linear behavior in the examined concentration range from1.0to220.0μg L-1, with the detection limit of0.15μg L-1for Cd(Ⅱ), offering good reproducibility. Compared with the bismuth-film electrode and antimony-film electrode, the bismuth-antimony film electrode displayed higher stripping current response. 2. Study on antimony/poly(p-aminobenzene sulfonic acid) film electrode and its application for measurement of lead (Ⅱ)A novel sensor was developed for detection of Pb(Ⅱ), based on the square wave anodic stripping voltammetry at an antimony/poly(p-aminobenzene sulfonic acid) film electrode in nondeaerated model solutions of hydrochloric acid (pH2). This new electrode was prepared by in situ depositing Sb(Ⅲ) and target metal ion on the poly(p-ABSA) coated glassy carbon electrode (GCE). Under the optimum conditions, a linear response was observed for Pb(Ⅱ) in the range from0.50to150.00(xg L-1. The detection limit of Pb(Ⅱ) was0.10μg L-1. Compared with the antimony film electrode (SbFE) and poly(p-aminobenzene sulfonic acid) film electrode (poly(p-ABSA)FE), the Sb/poly(p-ABSA)FE can yield a larger stripping signal for Pb(Ⅱ). And it was applied to the determination of Pb(Ⅱ) in water samples.3. Study on bismuth-modified graphene oxide doped carbon paste electrode and its application for measurement of lead (Ⅱ) and cadmium (Ⅱ)A bismuth film modified graphene oxide doped carbon paste electrode (Bi/GO/CPE) was employed for the determination of trace Pb(Ⅱ) and Cd(Ⅱ). The simultaneous determination of Pb(Ⅱ) and Cd(Ⅱ) was performed by square wave anodic stripping voltammetry. Under the optimized condition, the Bi/GO/CPE presented well-defined, reproducible and sharp stripping signals. The peak current response increased linearly with the metal concentration in a range of1.0-40.0μg/L. The limit of detection was0.65μg/L for Pb(II) and0.54μg/L for Cd(II). And it was applied to the simultaneous determination of Pb(II) and Cd(Ⅱ) in water samples.4. Study on graphene modified glassy carbon electrode and its application for determination of uric acidA highly selective and sensitive graphene-modified glass carbon electrode has been used to detecte uric acid (UA) by differential pulse voltammetry. The results showed that this new electrochemical sensor exhibits excellent electrochemical activity. For the direct determination of uric acid, a linear calibration curve is obtained over the8.0-600.0μM range in0.1M pH6.5PBS solution, the detection limit is3.95μM. Furthermore, the practical analytical utility is illustrated by selective measurements of uric acid in human urine without any preliminary treatment and got satisfactory results. It’s a new electrochemical method for the detection of uric acid. |
PDF Full Text Request