Pervaporation-flow injection determination of ammonia in the presence of surfactants Original Research Article

A pervaporation flow-injection method is described for the analysis of ammonia in complex matrices (e.g. in the presence of surfactants, solid particles). The donor solution is 1.0 mol l−1 NaOH while the acceptor solution contains mixed acid–base indicators cresol red and thymol blue. The color change resulting from the ammonia entering the acceptor stream in the pervaporation unit is monitored photometrically at 590 nm. The method is characterized by a linear calibration range between 0.2 and 20 mg l−1, sampling frequency of 11 h−1 and detection limit of 0.1 mg l−1. The presence of surfactants in high concentrations (1000 mg l−1) does not affect the analytical determination. The method was applied successfully to industrial effluents containing ammonia in the presence of surfactants, other organics and suspended solids.