Pervaporation-flow injection determination of ammonia in the presence of surfactants

A pervaporation flow-injection method is described for the analysis of ammo nia in complex matrices (e.g. in the presence of surfactants, solid particl es). The donor solution is 1.0 mol l(-1) NaOH while the acceptor solution c ontains mixed acid-base indicators cresol red and thymol blue. The color ch ange resulting from the ammonia entering the acceptor stream in the pervapo ration unit is monitored photometrically at 590 nm. The method is character ized by a linear calibration range between 0.2 and 20 mg l(-1), sampling fr equency of 11 h(-1) and detection limit of 0.1 mg l(-1). The presence of su rfactants in high concentrations (1000 mg l(-1)) does not affect the analyt ical determination. The method was applied successfully to industrial efflu ents containing ammonia in the presence of surfactants, other organics and suspended solids. (C) 2000 Elsevier Science B.V. All rights reserved.