A FLUORESCENCE-BASED SENSOR FOR AMMONIUM AND NITRATE

Measurement of nitrite and nitrate in rain samples was performed using a fluorescence based sensor. Nitrite and nitrate were reduced to ammo nia using Devarda's alloy, and the gas was then passed through a membr ane and reacted with o-phthalaldehyde. A linear relationship between t he nitrate concentration and the luminescence intensity was observed o ver the concentration range of 1 - 5 mg/l, with a relative standard de viation (RSD) of 2.3% at a nitrate concentration of 1 mg/l (n = 5). Th e system did not show any response toward sulfate or chloride. Results obtained from the measurement of river water samples using the sensor showed goad agreement with those obtained using a conventional method .