Sensor calibration was carried out by using various concentrations
of ammonia gas obtained by mixing nitrogen and
100 ppm synthetic ammonia in nitrogen with mass flow controllers.
The sensor was fitted to the aperture of the optical
scanner head and placed, through an airtight rubber seal, into
a ca. 57.4 cm3 flow cell (4.7 cm×4.7 cm×3.3 cm: L×W×H)
to monitor in real time the sensor responses to changing ammonia
concentration. The data was logged by a PC connected to
the optical scanner