NEAR-INFRARED REAGENTS FOR FIBEROPTIC AMMONIA SENSORS

Representatives of three types of near-infrared dyes, i.e., Cu(II) com plex of 5-(N'-diethylamino-phenylimino)quinoline (D1), MR acid-base in dicator thylamino-phenyl]-divinylene-carbenium-perchlorate (D2) and sq uaraine dye (D3), have been tested as reagents for fibre-optic ammonia sensors. Both D1 and D2 show reversible response to ammonia and are t hus suitable for the monitoring of gas ammonia. D1 has low stability a nd hence cannot be easily incorporated into a polymer matrix or silica matrix prepared by the sol-gel method. D2 can be incorporated into th e silica matrix. D3 is also sensitive to ammonia, but the sensitivity is solvent dependent and the response is irreversible.