Département de chimie moléculaire

An interdigitated conductimetric electrode system using a combination of peroxidase/catalase has been developed to det. nitrite in water samples. A peroxidase (HRP) was located in the inner layer while the outer contained catalase. Catalase catalyzed the breakdown of H2O2 into H2O and O2 thus consuming totally H2O2, the substrate of HRP. The latter, in presence of H2O2, generates a conductometric signal due to the redn. of H2O2. Nitrite was selected as an inhibitor of catalase. In the presence of H2O2, the nitrite addn. blocked the H2O2 consumption by catalase. Since nitrite had no effect on HRP activity, its inhibitive effect on catalase leads to an increase in the conductometric signal. The bienzyme sensor exhibits an increase in conductometric response for nitrite concn., leading to high values of cond. In both cases, the detection limit of nitrite is 0.3 $μ$M and for bienzyme sensor the dynamic range is from 0.3 $μ$M to 446 $μ$M. [on SciFinder(R)]