University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Xing-Zheng Wu

Abbrev:
Wu, X.Z.
Other Names:
Address:
Department of Materials Science and Engineering, Faculty of Engineering, Fukui University, 3-9-1, Bunkyo, Fukui-shi 910-8507, Japan
Phone:
+81-776-27-8610
Fax:
+81-776-27-8767

Citations 6

"New Approaches To Sample Preparation For Capillary Electrophoresis"
Trends Anal. Chem. 2003 Volume 22, Issue 1 Pages 48-58
Xing-Zheng Wu

Abstract: Recent developments in sample preparation for capillary electrophoresis (CE) are discussed. In particular, on-line chemical or chromatographic sample clean-up concentration methods, on-line electrophoretic concentration methods, and on-line sample filtration and clean-up with a semi-permeable membrane for various CE modes are described.

"Chemiluminescence Study Of Active Oxygen Species Produced By TiO 2 Photocatalytic Reaction"
Luminescence 2005 Volume 20, Issue 1 Pages 36-40
Xing-Zheng Wu*, Min Lingyue, Keiko Akiyama

Abstract: Two chemiluminescence approaches have been used for study of active oxygen species produced by the TiO2 photocatalytic reaction. One is based on flow injection analysis (FIA)-luminol chemiluminescence (CL); another is a time-resolved CL method. In the FIA-CL experiment, an UV-illuminated TiO 2 suspension and water were passed into a mixing cell by two separate flow lines. Luminol solution was injected into the water flow line at different times. The injected luminol reacted with active oxygen species generated by the TiO2 photocatalytic reaction in a mixing coil and produced CL. It was found that the maximum CL was detected at the first injection of luminol. CL intensity decreased with time of injection. When the luminol was injected after 5 min, the CL intensity was almost unchanged. Addition of scavengers of active oxygen species indicated that the CL produced early in the 5 min was caused by O2- and H2O2, while CL after 5 min was only from H2O2. In the time-resolved CL, the third harmonic wavelength of Nd:YAG laser (355 nm) was used as a UV light source, and CL was detected by a PMT and recorded in a millisecond time scale using a digital oscilloscope. It was found that CL induced by the photocatalytic reaction increased with concentration of the TiO2 suspension. Scavengers of active oxygen species of .OH, O2- and H2O2 were added to study the involvement of the active oxygen species.

"A Novel Chemical Measurement Method Based On Reaction-heat-induced Optical Beam Deflection"
Bunseki Kagaku 1996 Volume 45, Issue 1 Pages 55-64
Wu, X.Z.

Abstract: The heat evolved in a reaction induces the formation of an RI gradient near the interface of a two-phase system and thereby deflects a laser beam travelling initially along the interface. The deflected beam is attenuated by a knife-edge, or the deflection is measured directly with a position-sensitive detector. Batch and FIA experimental systems based on this effect are illustrated. The magnitude of the effect is proportional to the amount of a reactant.

"Several Factors Affecting The Detection Sensitivity Of The Reaction Heat-induced Optical Beam Deflection Method"
Bull. Chem. Soc. Jpn. 1996 Volume 69, Issue 12 Pages 3423-3428
Xing-Zheng Wu*, Hideki Kitatani, Katsumi Uchiyama, and Toshiyuki Hobo

Abstract: In order to improve the detection sensitivity of the reaction heat-induced optical beam deflection method, the experimental factors that affect the detection sensitivity were investigated in detail. Firstly, different types of deflection detectors were compared. The experimental results showed that the bi-cell photodiode detector is most sensitive to the deflection signal. Secondly, the effect of the size of the reaction cell on the detection sensitivity was investigated. A small reaction cell gave a stable baseline and small noise in flow injection experiments, and thus gave a high detection sensitivity. Thirdly, the effects of the optical arrangements on the detection sensitivity were investigated. Focusing the probe beam close to the gold film/CCl4 interface enhanced the detection sensitivity. Also, refocusing the deflected probe beam improved the sensitivity. Under the selected experimental conditions, the detection of the neutralization reaction between HCl and NaOH at sub-nanomol level became possible. Further improvements are also discussed. 26 References
Hydrochloric acid Sodium hydroxide Spectrometry Flowcell Optimization Photodiode

"Detection Method Based On A Surface Plasmon Resonance And Its Application To Flow Injection Analysis And Liquid Chromatography"
Bull. Chem. Soc. Jpn. 1996 Volume 69, Issue 7 Pages 1969-1974
Xing-Zheng Wu*, Masamitsu Nakagawa, Chiaki Nagamori, Katsumi Uchiyama, and Toshiyuki Hobo

Abstract: The surface plasmon resonance (SPR) detector described consists essentially of a hemicylindrical prism (1 cm diameter x 2 cm) having its flat face coated with a 50 nm film of Ag, and a 3.5 µL flow cell formed by a slit (7 mm x 1 mm) in a piece of 0.5 mm thick PTFE sheet held against the silvered face by a brass holder (diagram given) mounted on a rotating stage so that the angle of incidence could be varied. The generation of SPR in water in the flow cell is demonstrated. SPR detection based on change in the coupling angle and in the reflectivity at a fixed angle were investigated both experimentally and theoretically, and the latter mode is shown by simulation and experiment to be much the more sensitive for the system described. A calibration graph (illustrated) of the reflectivity change vs. propan-2-ol concentration in 20 µL aqueous samples injected into a stream of water in a flow injection system was roughly linear for 0.1-1% of propan-2-ol. Also, a chromatogram obtained by monitoring the reflectivity change is shown for ethanol and propan-2-ol separated on an ODS column.
Ethanol 2-Propanol HPLC Detector Instrumentation

"Thermo-optical Flow Injection Determination For Hydrogen Peroxide Based On An Enzymic Reaction Heat-induced Optical Beam Deflection"
Anal. Chim. Acta 1995 Volume 299, Issue 3 Pages 333-336
Xing-Zheng Wu*, Hiroaki Shindoh and Toshiyuki Hobo

Abstract: A reaction cell was fabricated from a 6 mm i.d. glass tube having a thin Au film carrying immobilized catalase mounted at one end. The cell was immersed in a CCl4 phase, having a water phase above to prevent evaporation, and a probe beam from a He-Ne laser at 632.8 nm was passed 1 mm from the Au film. Sodium phosphate buffer (0.01M) of pH 7.4 was pumped through the cell at 1.6 ml/min and H2O2 solution was introduced using a 40 µL injector. The heat of the decomposition reaction catalyzed by the enzyme induced a deflection in the probe beam which was measured by a knife-edge and a photodiode detection system. The immobilization of catalase by crosslinking with BSA was optimized to obtain a maximum deflection signal. This signal was linear over the concentration range 0.025-0.5 M of peroxide and the detection limit was 0.025M. The RSD for 0.5 M H2O2 solution (n = 20) was 0.93% and the enzyme activity was stable for at least two weeks.
Hydrogen peroxide Spectrometry Apparatus Immobilized enzyme Catalysis Photodiode