title: A chronoamperometric screen printed carbon biosensor based on alkaline phosphatase inhibition for W(IV) determination in water, using 2-phospho-L-ascorbic acid trisodium salt as a substrate.
abstract: This paper presents a chronoamperometric method to determine tungsten in water using screen-printed carbon electrodes modified with gold nanoparticles and cross linked alkaline phosphatase immobilized in the working electrode. Enzymatic activity over 2-phospho-l-ascorbic acid trisodium salt, used as substrate, was affected by tungsten ions, which resulted in a decrease of chronoamperometric current, when a potential of 200 mV was applied on 10 mM of substrate in a Tris HCl buffer pH 8.00 and 0.36 M of KCl. Calibration curves for the electrochemical method validation, give a reproducibility of 5.2% (n = 3), a repeatability of 9.4% (n = 3) and a detection limit of 0.29 ± 0.01 µM. Enriched tap water, purified laboratory water and bottled drinking water, with a certified tungsten reference solution traceable to NIST, gave a recovery of 97.1%, 99.1% and 99.1% respectively (n = 4 in each case) and a dynamic range from 0.6 to 30 µM. This study was performed by means of a Lineweaver-Burk plot, showing a mixed kinetic inhibition.
authors.affiliation: School of Chemistry & CELEQ, University of Costa Rica, San Pedro de Montes de Oca, 11500-2060 San José, Costa Rica. ana.alvaradogamez@ucr.ac.cr.
authors.forename: Ana Lorena
authors.initials: AL
authors.lastname: Alvarado-Gámez
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain. malomillo@ubu.es.
authors.forename: María Asunción
authors.initials: MA
authors.lastname: Alonso-Lomillo
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain. olgado@ubu.es.
authors.forename: Olga
authors.initials: O
authors.lastname: Domínguez-Renedo
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain. jarcos@ubu.es.
authors.forename: María Julia
authors.initials: MJ
authors.lastname: Arcos-Martínez
mesh_terms: D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000737:chemistry; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D015374:Biosensing Techniques; D002244:Carbon / Q000737:chemistry; D004800:Enzymes, Immobilized; D006046:Gold / Q000737:chemistry; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D014414:Tungsten / Q000737:chemistry / Q000302:isolation & purification*; D014867:Water / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D012996:Solutions; D014867:Water; C011669:ascorbate-2-phosphate; D002244:Carbon; D006046:Gold; D000469:Alkaline Phosphatase; D001205:Ascorbic Acid; D014414:Tungsten