title: A miniature and field-applicable multipumping flow analyzer for ammonium monitoring in seawater with fluorescence detection.
abstract: In this article, a simple, economic, and miniature flow analyzer for ammonium in seawater based on the solenoid micropumps is presented. A single reagent of sodium tetraborate, ortho-phthaldialdehyde (OPA), and sodium sulfite was used and optimized applying the modified SIMPLEX method. A special-made detection cell for fluorescence detection of the reaction product isoindol-1-sulfonat was made and combined with a commercial photomultiplier tube, a long-pass optical filter, and an UV-LED as excitation light source. A LOD down to 13 nmol/L was achieved. The fabrication and application of a miniature reaction coil heating device for reaction rate enhancement is further described. The system featured an injection frequency of 32 h(-1) at average standard deviation of 3%.
authors.affiliation: Department of Global Change Research. IMEDEA (CSIC-UIB), Institut Mediterráni d'Estudis Avançats, Miquel Marques 21, 07190 Esporles, Spain.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Horstkotte
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Duarte
authors.forename: Víctor
authors.initials: V
authors.lastname: Cerdà
mesh_terms: D004784:Environmental Monitoring / Q000379:methods; D004867:Equipment Design; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods*; D005453:Fluorescence; D057230:Limit of Detection; D008904:Miniaturization; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D015203:Reproducibility of Results; D012623:Seawater / Q000737:chemistry*
chemical_list: D000644:Quaternary Ammonium Compounds