title: Enzymatic biosensors based on ingá-cipó peroxidase immobilised on sepiolite for TBHQ quantification.
abstract: Sepiolite clay mineral was used as a support for the immobilisation of the peroxidase enzyme from ingá-cipó (Inga edulis Mart.) and was used with graphite powder, multi-walled carbon nanotubes (CNTs), mineral oil, and nafion 0.5% (v/v) in the development of a new biosensor for the determination of the antioxidant tert-butylhydroquinone (TBHQ) by square-wave voltammetry (SWV). For the optimisation and application of the biosensor, several parameters were investigated to determine the optimum experimental conditions using SWV. The best performance was obtained using a 0.1 mol L(-1) phosphate buffer solution (pH 7.0), 4.0 × 10(-4) mol L(-1) hydrogen peroxide, a frequency of 50 Hz, a pulse amplitude of 60 mV, and a scan increment of 6 mV. The biosensor showed good repeatability and reproducibility and remained stable for a period of 20 weeks. The analytical curve revealed a linear response range of 1.65 to 9.82 mg L(-1) (r = 0.994) with detection and quantification limits of 0.41 and 1.25 mg L(-1). A recovery study of TBHQ in salad dressing samples yielded values from 99.6-104.8%. The proposed biosensor was successfully used for the determination of TBHQ in commercial salad dressing samples, giving a relative error of 5.4% in relation to the comparative method (chromatographic).
authors.affiliation: Departamento de Química, Grupo de Eletroquímica e Novos Materiais, Universidade Federal de Mato Grosso, 78060-900, Cuiabá, MT, Brazil. sallykm@gmail.com.
authors.forename: Tássia
authors.initials: T
authors.lastname: Regina de Oliveira
authors.forename: Gregory Ferreira
authors.initials: GF
authors.lastname: Grawe
authors.forename: Sally Katiuce
authors.initials: SK
authors.lastname: Moccelini
authors.forename: Ailton J
authors.initials: AJ
authors.lastname: Terezo
authors.forename: Marilza
authors.initials: M
authors.lastname: Castilho
mesh_terms: D015374:Biosensing Techniques; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006873:Hydroquinones / Q000737:chemistry*; D017633:Magnesium Silicates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010544:Peroxidases / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D006873:Hydroquinones; D017633:Magnesium Silicates; C018855:2-tert-butylhydroquinone; C001671:magnesium trisilicate; D010544:Peroxidases