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An amperometric glucose biosensor based on multi-walled carbon nanotube (MWCNT) modified glassy carbon electrode has been developed. MWCNT-modified glassy carbon electrode was obtained by casting the electrode surface with multi-walled carbon nanotube materials. Glucose oxidase was co-immobilized on the MWCNT-modified glassy carbon surface by electrochemical deposition of poly(o-phenylenediamine) film. Enhanced catalytic electroreduction behavior of oxygen at MWCNT-modified electrode surface was observed at a potential of À 0.40 V (vs. Ag j AgCl) in neutral medium. The steady-state amperometric response to glucose was determined at a selected potential of À 0.30 V by means of the reduction of dissolved oxygen consumed by the enzymatic reaction. Common interferents such as ascorbic acid, 4-acetamidophenol, and uric acid did not interfere in the glucose determination. The linear range for glucose determination extended to 2.0 mM and the detection limit was estimated to be about 0.03 mM.

Hydrazine compounds, including hydrazine (HZ), phenylhydrazine (PHZ), sernicarbazide (SCZ) and isoniazid (INZ) were separated and determined by capillary electrophoresis (CE) with a poly(glutamic acid) modified microdisk carbon fiber electrode. The modified electrode exhibited highly catalytic activity for hydrazines and has good stability. Linear responses for hydrazines over 2-3 orders of magnitude were obtained. The detection limits for HZ, PHZ, SCE and INZ were 7.8, 8.0, 14.0 and 11.0 fmol, respectively.3343

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