title: A gas diffusion technique coupled with flow injection systems. Optimization of the process in its application to the fluorimetric determination of ammonium in water samples.
abstract: A novel flow injection-gas-diffusion (GD-FI) system has been developed for the on-line analysis of ammonium ion in waters with fluorimetric detection, using an acceptor solution containing the Eosin-Bluish (EB) acid-base indicator. This, together with optimization of the process of gas transfer through the membrane, increases the sensitivity of the method to a considerable extent. Under optimum conditions, it is possible to determine the analyte within the 0.02-1.5 mg l(-1) range, with a limit of detection of 5 microg l(-1) and relative standard deviations (n = 12, [NH (4) (+) ] = 50 microg l(-1) and 0.05 microg l(-1)) of 3.4% and 3.0% respectively. The determination rate was 15 samples per hour.
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, University of Salamanca, Plaza de la Merced s/n, Salamanca, 37008, Spain. almendral@usal.es
authors.forename: María-Jesús
authors.initials: MJ
authors.lastname: Almendral-Parra
authors.forename: Angel
authors.initials: A
authors.lastname: Alonso-Mateos
authors.forename: María-Socorro
authors.initials: MS
authors.lastname: Fuentes-Prieto
mesh_terms: D002138:Calibration; D004058:Diffusion; D017022:Flow Injection Analysis / Q000379:methods*; D005470:Fluorometry / Q000379:methods*; D005740:Gases / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008567:Membranes, Artificial; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D005740:Gases; D008567:Membranes, Artificial; D000644:Quaternary Ammonium Compounds; D014867:Water