Development of a conductometric nitrate biosensor based on Methyl viologen/Nafion (R) composite film
Résumé
A conductometric biosensor for nitrate analytical determination was developed using nitrate reductase (NR) from Aspergillus niger immobilized oil a thin-film electrode by cross-linking with bovine scrum albumin in the presence of glutaraldehyde, Nafion (R) cation-exchange polymer and methyl viologen mediator. The process parameters for the fabrication of the enzyme electrode and various experimental variables were investigated with regard to their influence oil sensitivity, limit of detection, dynamic range, operational and storage stability. The biosensor call reach 95% of steady-state conductance value in about 13 s. Linear calibration in the range of 0.02 and 0.25 mM with detection limits of 0.005 mM nitrate was obtained with a signal-to-noise ratio of 3. When stored in 5 mM phosphate buffer (pH 7.5) at 4 degrees C, the sensor showed good stability over two weeks. The electrode is suitable for use ill real samples.