title: Continuous flow method for the simultaneous determination of phosphate/arsenate based on their different kinetic characteristics.
abstract: This paper proposes a new automated spectrophotometric method for the simultaneous determination of phosphate and arsenate without pre-treatment, which is faster, simpler, less expensive and hazardous than other well-known methods used with water samples. Such method is based on the different kinetic characteristics of complex formation of phosphate and arsenate with ammonium molybdate. A flow system was used in order to achieve good mixing and to provide precise time control. All the measurements were performed at the isosbestic point wavelength (885 nm). Chemical variables were optimized by factorial design (ammonium molybdate 0.015 mol L(-1), potassium antimony tartrate 1×10(-4) mol L(-1), and sulphuric acid 0.7 mol L(-1)). An appropriate linear range for both analytes (0.50-8.00μmolL(-1)), good inter-day reproducibility (4.9% [P] and 3.3% [P+As]) and a sample throughput of 6h(-1) were obtained. The detection limits are 0.4 μmol L(-1) P and 0.19 μmol (-1) [P+As] (3.3S y/x). The method was validated.
authors.affiliation: CICTERRA, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: Borgnino
authors.forename: Valeria
authors.initials: V
authors.lastname: Pfaffen
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Depetris
authors.forename: Miriam
authors.initials: M
authors.lastname: Palomeque
mesh_terms: D001149:Arsenates / Q000032:analysis* / Q000737:chemistry; D060766:Drinking Water / Q000032:analysis* / Q000737:chemistry; D017022:Flow Injection Analysis / Q000379:methods; D006801:Humans; D007700:Kinetics; D008982:Molybdenum; D010710:Phosphates / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results; D013053:Spectrophotometry / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D001149:Arsenates; D060766:Drinking Water; D010710:Phosphates; D014874:Water Pollutants, Chemical; D008982:Molybdenum; C022175:ammonium molybdate