Electrochemical Sensors Based On Ionic Liquids/Nano Materials Composite And Their Applications For The Determination Of Environmental Hormone

Environmental endocrine are chemicals that interfere with endocrine （orhormone system） in animals, including humans. These disruptions can causecancerous tumors, birth defects, and other developmental disorders. Specifically, theyare known to cause learning disabilities, severe attention deficit disorder, cognitiveand brain development problems, deformations of the body; sexual developmentproblems, feminizing of males or masculine effects on females, etc. Therefore justifyefforts for developing novel methods for the detect of environmental endocrine arevery important.Acetylene black （AB）, a quasi-nano-material, is a special type of carbon blackformed by an exothermic decomposition of acetylene, its nano-particles were arrangedwith chain-like structures, and the surface of particles is composed of graphite-likecrystal, therefore acetylene black has good conductivity and large specific surface area.Hydrotalcite is a layered double hydroxide of general formula whose name isderived from its resemblance with talc and its high water content. It is dimorphouswith and often intermixed with manasseite. Hydrotalcite has good exchangecapabilities. Ionic liquids （ILs）, comprising of organic cations and various anions, aresalts with melting points around room temperature. They possess many favorableproperties, such as negligible vapor pressure, non-flammability, good chemicalstability and extractive capability. Hence, they are very useful in organic synthesis,separation field, etc. Recently, they attract much attention in electroanalysis, probablydue to their good electric conductivity and large electrochemical windows.In this paper, several electrochemical sensors based on ionic liquids, hydrotalciteand cetylene black have been developed, and are successfully applied to thedetermination of environmental endocrine. This paper mainly includes:1) a ionic liquid of1-butyl-3-methylimidazolium hexafluorophosphate was usedas modifier to make a ionic liquid-acetylene black modified electrode, which wasfurther characterized by electrochemical methods. The fabricated IL-AB modifiedelectrode showed good electrocatalytic behaviors towards the oxidation ofractopamine with the enhancement of the peak current. The electrochemical behaviorsof ractopamine on the IL-AB modified electrode were carefully studied and theelectrochemical parameters were calculated. Based on the electrocatalytic reaction, a new electrochemical method for the ractopamine determination was established in theconcentration range from8.0×10^-8to3.0×10^-5mol/L by linear voltammetry with thedetection limit estimated to be7×10^-9mol/L （3σ）. The established method wassuccessfully applied to the detection of ractopamine in pork samples with goodrecovery.2) An ionic liquid （i.e.1-butyl-3-methylimidazolium hexafluorophosphate）–magnesium aluminum hydrotalcite modified glassy carbon electrode （IL–MAH/GCE）has been fabricated. The electrode shows good electro-catalysis to the oxidationoftrifluralin and trifluralin can accumulate effectively on it. Thus, trifluralin can producea sensitive anodic peak on the IL–MAH/GCE/GCE. Parameters influencing thevoltammetric response of trifluralin are optimized for trifluralin determination. Underthe selected experimental conditions, the peak current is linear to trifluralinconcentration over the range of8.0×10^-8to1.0×10^-5mol/L. The detection limit is2×10^-8mol/L. This electrode has been applied to the determination of trifluralin inreal samples.3) In this chapter, a nickel aluminum hydrotalcite-ionic liquid modified electrodefor the determination of diethylstilbestrol was developed. The hydroxyapatite whichcombines with ionic liquid plays an important role in remarkable electrochemicalresponses of diethylstilbestrol. Trace analysis of the diethylstilbestrol was performedby anodic stripping voltammetry. The oxidation of diethylstilbestrol yieldedwell-defined peak currents. The peak currents at about0.47V for diethylstilbestrolwere measured. The affecting factors containing supporting electrolyte, pH of solution,accumulation time, deposition potential and possible interferences were investigated.The sensor exhibited good linear behavior in the range of9.0×10^-8mol/L to1.8×10^-5mol/L for diethylstilbestrol with detection limits of1.0×10^-8mol/L. This electrodehas been applied to the determination of diethylstilbestrol in real samples.