title: Iron speciation in natural waters by sequential injection analysis with a hexadentate 3-hydroxy-4-pyridinone chelator as chromogenic agent.
abstract: A sequential injection method for iron speciation in various types of natural waters was developed using a synthesised hexadentate 3-hydroxy-4-pyridinone chelator (CP256). The denticity of the ligand that allow formation of the corresponding iron(III) complex in a 1:1 stoichiometry proved to be highly advantageous, in comparison with parent bidentate, hydroxy-4-piridinone chelators, with a two fold increase of reaction sensitivity and over 65% decrease of the LOD. A solid phase extraction approach was employed to attain matrix elimination, facilitating iron(III) determination and application to high salinity waters. The combination with the total iron determination obtained by the direct reaction of the ligand resulted in iron speciation. Two detection spectrophotometric cells were tested, a conventional flow cell (CFC) and a liquid waveguide capillary cell (LWCC). The dynamic concentration ranges were 0.1-2 mg/L with the CFC detection and 0.005-0.1 mg/L with the LWCC, with limit of detection of 30 µg/L and 6 µg/L, respectively. The developed method was successfully applied to a variety of natural waters.
authors.affiliation: CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: Joana L A
authors.initials: JL
authors.lastname: Miranda
authors.affiliation: CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal; Laboratório de Hidrobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal. Electronic address: rmesquita@porto.ucp.pt.
authors.forename: Raquel B R
authors.initials: RB
authors.lastname: Mesquita
authors.affiliation: REQUIMTE, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Rua de Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Nunes
authors.affiliation: REQUIMTE, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Rua de Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal.
authors.forename: Maria
authors.initials: M
authors.lastname: Rangel
authors.affiliation: CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: António O S S
authors.initials: AO
authors.lastname: Rangel
mesh_terms: D017022:Flow Injection Analysis / Q000379:methods; D005618:Fresh Water / Q000032:analysis*; D007501:Iron / Q000032:analysis*; D007502:Iron Chelating Agents / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*
chemical_list: D007502:Iron Chelating Agents; D011728:Pyridones; C020366:3-hydroxy-4-pyridone; D007501:Iron
keywords: Fresh and saline water samples; Hexadentate 3,4-hydroxypiridinone ligand; Iron speciation; Solid phase extraction