title: Speciation of chromium using chronoamperometric biosensors based on screen-printed electrodes.
abstract: Chronoamperometric assays based on tyrosinase and glucose oxidase (GOx) inactivation have been developed for the monitoring of Cr(III) and Cr(VI). Tyrosinase was immobilized by crosslinking on screen-printed carbon electrodes (SPCEs) containing tetrathiafulvalene (TTF) as electron transfer mediator. The tyrosinase/SPC(TTF)E response to pyrocatechol is inhibited by Cr(III). This process, that is not affected by Cr(VI), allows the determination of Cr(III) with a capability of detection of 2.0±0.2 μM and a reproducibility of 5.5%. GOx modified screen-printed carbon platinised electrodes (SPCPtEs) were developed for the selective determination of Cr(VI) using ferricyanide as redox mediator. The biosensor was able to discriminate two different oxidation states of chromium being able to reject Cr(III) and to detect the toxic species Cr(VI). Chronoamperometric response of the biosensor towards glucose decreases with the presence of Cr(VI), with a capability of detection of 90.5±7.6 nM and a reproducibility of 6.2%. A bipotentiostatic chronoamperometric biosensor was finally developed using a tyrosinase/SPC(TTF)E and a GOx/SPC(Pt)E connected in array mode for the simultaneous determination of Cr(III) and Cr(VI) in spiked tap water and in waste water from a tannery factory samples.
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, Burgos 09001, Spain. Electronic address: anacp@ubu.es.
authors.forename: Ana
authors.initials: A
authors.lastname: Calvo-Pérez
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, Burgos 09001, Spain. Electronic address: 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, Burgos 09001, Spain. Electronic address: malomillo@ubu.es.
authors.forename: M Asunción
authors.initials: MA
authors.lastname: Alonso-Lomillo
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, Burgos 09001, Spain. Electronic address: jarcos@ubu.es.
authors.forename: M Julia
authors.initials: MJ
authors.lastname: Arcos-Martínez
mesh_terms: D015374:Biosensing Techniques; D002857:Chromium / Q000032:analysis / Q000145:classification*; D055664:Electrochemical Techniques; D004566:Electrodes
chemical_list: D002857:Chromium
keywords: Biosensor; Chromium speciation; Enzymatic inhibition; Glucose oxidase; Screen-printed electrodes; Tyrosinase