title: A bulk liquid membrane-flow injection (BLM-FI) coupled system for the preconcentration and determination of vanadium in saline waters.
abstract: A bulk liquid membrane-flow injection (BLM-FI) system has been developed for the preconcentration and spectrophotometric determination of vanadium in saline waters. The preconcentration step was based on a bulk liquid membrane containing Aliquat 336 (acting as a carrier) dissolved in dodecane/dodecanol. Vanadium species were chemically pumped due to the pH gradient between the sample (pH 3.2) and the receiving solution (pH 9.8). Vanadium transport through the membrane was monitored by a new and sensitive spectrophotometric method based on its reaction with di-2-pyridyl ketone benzoylhydrazone (dPKBH) in an acidic medium. As a consequence of membrane transport, vanadium was recovered in an ammonium solution, where total vanadium concentration was spectrophotometrically determined at 375 nm, as the pentavalent species, by using a flow injection analysis (FIA) system. Under optimal conditions, this FIA system provided a detection limit of 4.7 μg L(-1) (3s(blank)/m) and RSD 2.72%, for vanadium determination in saline samples. Both preconcentration and determination steps were previously optimized by modified simplex methodologies. The proposed coupled method was successfully applied to the determination of vanadium in a certified reference material (TMDA-62) and in two seawater samples.
authors.affiliation: Department of Analytical Chemistry, Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Spain. juanjose.pinto@uca.es
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Pinto
authors.forename: Manuel
authors.initials: M
authors.lastname: García-Vargas
authors.forename: Carlos
authors.initials: C
authors.lastname: Moreno
mesh_terms: D004396:Coloring Agents / Q000737:chemistry; D017022:Flow Injection Analysis; D006835:Hydrazones / Q000737:chemistry; D057230:Limit of Detection; D008567:Membranes, Artificial; D011725:Pyridines / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012623:Seawater / Q000032:analysis*; D014639:Vanadium / Q000032:analysis*
chemical_list: D004396:Coloring Agents; D006835:Hydrazones; D008567:Membranes, Artificial; D011725:Pyridines; D000644:Quaternary Ammonium Compounds; C511463:di-2-pyridyl ketone benzoyl hydrazone; D014639:Vanadium; C037759:trioctylmethylammonium