A novel hydrogen peroxide biosensor has been constructed based on the characteristics of the carbon nanotube. The multiwall carbon nanotube (MWNT) was used as a coimmobilization matrix to incorporate horseradish peroxidase (HRP) and electron transfer mediator methylene blue (MB) onto a glassy carbon electrode surface. Cyclic voltammetry and amperometric measurements were employed to demonstrate the feasibility of methylene blue as an electron carrier between the immobilized peroxidase and the surface of glassy carbon electrode. The amperometric response of this resulting biosensor to H 2 O 2 shows a linear relation in the range from 4 mM to 2 mM. The detection limit was 1 mM when the signal to noise ratio is 3. The presence of dopamine and ascorbic acid hardly affects the sensitive determination of H 2 O 2 . This biosensor also possesses very good stability and reproducibility.

A new method was developed for the speciation of inorganic arsenic in coal samples by liquid chromatography coupled to hydride generation atomic fluorescence spectrometry after microwave-assisted extraction. Effective extract of As(III), As(V) in coal sample was achieved by 1.0molL-1 H3PO4 and 0.1 molL-1ascorbic acid. Under the optimized conditions, the limits of detection were 0.01 ugL-1and 0.02 ugL-1for As(III), As(V). The relative standard deviation were 2.4 %, 3.3 % (c= 20.0 gL-1, n=7). The proposed method was successfully applied for the determination of speciation of inorganic arsenic in coal samples and GBW11117.