NO(2) Sensor which uses immobilized nitrite oxidizing bacteria

A biosensor consisting of immobilized nitrite oxidizing bacteria and an oxygen electrode has been developed for the amperometric determination of NO(2) (nitrogen dioxide) gas. The response time for the determination of NO(2) was within 3 min. A linear relationship was observed between the current decrease and the NO(2) concentration below 255 ppm. The minimum concentration for the determination of NO(2) was 0.51 ppm. The current decrease was reproducible within +/-4% of the relative error. The selectivity of the microbial sensor for NO(2) was satisfactory. The current output of the sensor was almost constant for more than 24 days and 400 assays.