Table of Contents

Abstract: Differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) at a hanging mercury drop electrode (HMDE) was used for the determination of trace amounts of carcinogenic nitrobiphenyls, namely 2-nitrobiphenyl (2-NBP), 3-nitrobiphenyl (3-NBP) and 4-nitrobiphenyl (4-NBP) within the concentration range from 2.10^-8 to 1.10^-5 mol⋅L^-1 for DPV and from 2.10^-9 to 1.10^-7 mol⋅L^-1 for AdSV using a Britton-Robinson buffer – methanol (1:1) mixture with resulting pH 12 as a base electrolyte. The practical applicability of newly developed methods was verified using model samples of drinking and river water and liquid-liquid extraction for a preliminary separation and preconcentration.

Abstract: 2-Mercaptoethanol self-assembled monolayer (ME/Au SAMs) was prepared on a gold electrode. The ME/Au SAMs was characterized by using ATR-FTIR and dynamic contact angle measurements. The electrochemical behaviors of noradrenaline (NE) on the ME/Au SAMs were studied in BR buffer solution. The modified electrode accelerated electron transfer rate of the redox of NE and showed an excellent eletrocatalytic activity. The diffusion coefficient (D) of NE was obtained to be 4.3×10^-8 cm² s^-1. The catalytic current increased linearly with the concentration of NE in the range of 2.0×10^-6 -1.0×10^-3 M by square wave voltammetry response. The modified electrode could eliminate the interference of ascorbic acid (AA) at 40-fold concentration of NE and could be satisfactorily used for the determination of NE in the drug injection.

Abstract: A wireless sensor network is presented for in-situ monitoring of atmospheric hydrogen concentration. The hydrogen sensor network consists of multiple sensor nodes, equipped with titania nanotube hydrogen sensors, distributed throughout the area of interest; each node is both sensor, and data-relay station that enables extended wide area monitoring without a consequent increase of node power and thus node size. The hydrogen sensor is fabricated from a sheet of highly ordered titania nanotubes, made by anodization of a titanium thick film, to which platinum electrodes are connected. The electrical resistance of the hydrogen sensor varies from 245 Ω at 500 ppm hydrogen, to 10.23 kΩ at 0 ppm hydrogen (pure nitrogen environment). The measured resistance is converted to voltage, 0.049 V at 500 ppm to 2.046 V at 0 ppm, by interface circuitry. The microcontroller of the sensor node digitizes the voltage and transmits the digital information, using intermediate nodes as relays, to a host node that downloads measurement data to a computer for display. This paper describes the design and operation of the sensor network, the titania nanotube hydrogen sensors with an apparent low level resolution of approximately 0.05 ppm, and their integration in one widely useful device.