Chiang Mai Journal of Science

     A porous membrane-based diffusion scrubber was fabricated to couple with a conductometric detector as a flow-batch system for determining ammonium in turbid surface waters. A gravity flow of DI water as a gas absorbing liquid and a manual sample introduction was employed to develop a cost- effective device without using a conventional pump and an injection valve. The standard calibration graph was linear in the range of 5 – 100 μmol L^-1, with a relative standard deviation of < 5%. The detection limit based on the lowest concentration in the calibration graph of 5 μmol L^-1 can be obtained. The results of ammonium determination using the proposed method agree well with those using the batch-wise indophenol blue as a standard method. The proposed analytical system provides a cost-effective setup and easy operation for ammonium determination in some turbid surface waters samples without requiring a fi ltering process and conventional glassware.