Application Of Disposable Electrochemical Sensors Based On Nanomaterials In The Environmental Monitoring

Three sensitive, rapid, facile and portable electrochemical sensors were developed by using screen printed technique, nanotechnology and electrochemical technique for the determination of pollutants in water.The disposable screen-printed electrodes modified with mercury nano-droplets and capable of sensing heavy metal ions were fabricated. They were prepared by coating electrodes with a mixture of multi-walled carbon nanotubes and chitosan, this followed by adsorption of mercury. It is shown that square wave anodic stripping voltammetry enables simultaneous determination of cadmium (Ⅱ), lead (Ⅱ) and copper (Ⅱ), for which detection limits of 12,23 and 20 nmol/L, respectively, are found. Relative standard deviations for ten determinations at 0.6μmol/L concentrations of these ions are in the range of 3.0 to 5.7%.Reduced graphene oxide (RGO) was dispersed in water through non-covalent functionalization with a water-soluble dye, Alizarin Red S (ARS). A thin film of ARS-RGO nano-composite was successfully deposited onto the surface of screen printed electrode by electro-polymerization. The modified electrode was utilized to determinate phenolic compounds in water. The ARS-RGO modified SPE had obvious electrocatalytic activity for the redox reactions of hydroquinone, catechol and dopamine. By using differential pulse voltammetry, the phenolic compounds can be determined sensitively. For hydroquinone, catechol and dopamine, the oxidation peak currents are linear to the concentrations at the range of 8.00×10-6～5.00×10-4 mol/L,8.00×10-6～5.00×10-4 mol/L and 5.00×10-6～5.00×10-4 mol/L, with the detection limits of 4.34×10-6 mol/L,3.42×10-6mol/L and 1.23×10-6 mol/LA highly efficient enzyme-based screen printed electrode was obtained by using covalent attachment between 1-pyrenebutanoic acid, succinimidyl ester adsorbing on the graphene oxide sheets and amines of tyrosinase-protected gold nanoparticles. The fabricated disposable biosensor exhibited a rapid amperometric response with a high sensitivity and good storage stability for monitoring catechol. This method shows a good linearity in the range from 8.3×10-8 to 2.3×10-5 mol/L for catechol with a detection limit of 2.4×10-8 mol/L.