Vitamin B12 incorporated with multiwalled carbon nanotube composite film for the determination of hydrazine

Electrochemically active composite film containing multiwalled carbon nanotubes (MWCNTs) and vitamin B-12 was synthesized on glassy carbon, gold, and indium tin oxide electrodes by the potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-B-12) modified electrode mediates vitamin B-12's redox reaction, whereas vitamin B-12's redox reaction does not occur at bare electrode. The electrochemical impedance spectroscopy studies reveal that MWCNTs present in MWCNT-B-12 film enhance electron shuttling between the reactant and electrode surface. The surface morphology of bare electrode, MWCNT film. and MWCNT-B-12 composite film was studied using atomic force microscopy, which reveals vitamin B-12 incorporated with MWCNTs. The MWCNT-B-12 composite film exhibits promising enhanced electrocatalysis toward hydrazine. The electrocatalysis response of hydrazine at MWCNT film and MWCNT-B-12 composite film was measured using cyclic voltammetry and amperometric current-time (i-t) curve techniques. The linear concentration range of hydrazine obtained at MWCNT-B-12 composite film using the i-t curve technique is 2.0 mu M-1.95 mM. Similarly, the sensitivity of MWCNT-B-12 composite film for hydrazine determination using the i-t curve technique is 1.32 mA mM(-1) cm(-2), and the hydrazine's limit of detection at MWCNT-B-12 composite film is 0.7 mu M. (c) 2010 Elsevier Inc. All rights reserved.