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Abstract: A new and simple method for fabricating controllable insulated nanometer-sized platinum electrodes is presented. Electrochemical etching of platinum wire is employed, and then a repeated process of cycle voltammetric deposition of electrophoretic paint and heat curing for shrink film follows which effectively controls the size of the nanoelectrodes, which is different from previous DC electrolysis deposition. This technique allows complete insulation of the whole body of the etched platinum wire, except for the very tip with the shrink film during heat curing of the film, leaving an electrochemical active area with effective diameters of nanometers. The process overcomes the pinhole formation resulting from the electrophoretic paint deposition process. The size of the platinum electrodes and the thickness of the deposed paint for insulation can be properly controlled and reproduced. The fabricated electrodes show ideal steady-state voltammetric behaviors from which the effective areas of the nanoelectrodes are measured. The effective radius of the prepared nanoelectrodes ranges from 3.1nm to hundreds of nanometers. [Copyright &y& Elsevier]

Abstract: Sequential injection lab-on-valve (LOV) was first proposed for analyzing ultra-trace amounts of Pb using differential pulse anodic stripping voltammetry (DPASV) with a miniaturized electrochemical flow cell fabricated in the LOV unit. Deposition and stripping processes took place between the renewable mercury film carbon paste electrode and sample solution, the peak current was employed as the basis of quantification. The mercury film displayed a long-term stability and reproducibility for at least 50 cycles before next renewal, the properties of integrated miniature LOV unit not only enhanced the automation of the analysis procedure but also declined sample/reagent consumption. Potential factors that affect the present procedure were investigated in detail, i.e., deposition potential, deposition time, electrode renewable procedure and the volume of sample solution. The practical applicability of the present procedure was demonstrated by determination of Pb in environmental water samples. [Copyright &y& Elsevier]

Abstract: Nonelectroactive acetochlor can be indirectly determined through the photocatalytical degradation of acetochlor. A derivative visible light photoelectrochemical sensor for indirect detection of the herbicide acetochlor using TiO2–poly(3-hexylthiophene)–ionic liquid nanocomposite is constructed. Poly(3-hexylthiophene) (P3HT) was synthesized via chemical oxidative polymerization with anhydrous FeCl3 as oxidant, 3-hexylthiophene as monomer, chloroform as solvent, and the functional TiO2 nanoparticles were facilely prepared by blending TiO2 nanoparticles and P3HT at room temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate solution. Operational parameters, including the photolysis time, ratios of TiO2 to P3HT, bias voltage and pH of buffer solution have been optimized. Under optimal conditions, the proposed photoelectrochemical method could detect acetochlor ranging from 0.5 to 20μmolL−1 with a detection limit of 0.2nmolL−1 at a signal-to-noise ratio of 3. The assay results of acetochlor in water samples with the proposed method were in acceptable agreement with those of the gas chromatograph–mass spectrometer (GC–MS) method. The promising sensor opens a new opportunity for fast, portable, and sensitive analysis of acetochlor in environmental samples. [Copyright &y& Elsevier]

Abstract: A Fe3O4/multiwall carbon nanotubes/β-cyclodextrin (Fe3O4/MWCNTs/β-CD) modified electrode, for highly sensitive and automated hypoxanthine measurements, was developed in a sequential injection lab-on-valve system. The electrochemical oxidation behavior of hypoxanthine was investigated in phosphate buffer solution by cyclic voltammetry and linear sweep voltammetry. The Fe3O4/MWCNTs/β-CD modified electrode exhibits preferably analytical characteristics in electrocatalytic activity towards the oxidation of hypoxanthine. Under optimized conditions, the log oxidation peak current intensity was proportional to log hypoxanthine concentration covering the range from 5.0×10−8 to 1.0×10−5 molL−1 with a correlation coefficient of 0.9965. A detection limit of 0.3×10–8 molL−1 was achieved along with a sampling frequency of 20h−1. This hyphenated system offers some advantages in terms of rapidness, sensitivity and ease of manipulation. Its further applications were utilized for the determination of hypoxanthine in meat samples. [Copyright &y& Elsevier]