A reagentless amperometric carbon paste based sensor for NADH

Carbon paste electrodes, based on zirconium phosphate with immobilized N-me thylphenazonium or Nile blue, were prepared. The electrodes show anodic cur rent response to NADH at an operating potential ranging from - 0.05 to 0.30 V (vs. SCE). The sensitivity of electrodes to NADH was shown to increase w ith increasing operation potential. It was shown that the concentration dep endences for electrodes, obtained at different operating potentials. follow Michaelis-Menten scheme. confirming an electrodcatalytic mechanism for ele ctrooxidation of NADH with a precursor complex formation. The detection lim it for NADH was found to be ca. 2 mu M for both types of sensors.