title: Determination of thiodicarb using a biosensor based on alfalfa sprout peroxidase immobilized in self-assembled monolayers.
abstract: A biosensor based on alfalfa sprout (Medicago sativa) homogenate as a source of peroxidase is proposed for the determination of thiodicarb by square-wave voltammetry. This enzyme was immobilized in self-assembled monolayers of l-cysteine on a gold electrode. Several parameters were investigated to evaluate the optimum conditions for operation of the biosensor. The analytical curve was linear for thiodicarb concentrations of 2.27 x 10(-6) to 4.40 x 10(-5) mol L(-1) with a detection limit of 5.75 x 10(-7) mol L(-1). The lifetime of the Au-alfalfa sprout-SAMs was 20 days (at least 220 determinations). The average recovery of thiodicarb from samples of vegetable extracts ranged from 99.02 to 101.04%. The results obtained for thiodicarb in vegetable extracts using the proposed method are in close agreement with those using a high performance liquid chromatography procedure at the 95% confidence level.
authors.affiliation: Departamento de Química, Laboratório de Biossensores, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC, Brazil. sallykm@gmail.com
authors.forename: Sally K
authors.initials: SK
authors.lastname: Moccelini
authors.forename: Iolanda C
authors.initials: IC
authors.lastname: Vieira
authors.forename: Fábio
authors.initials: F
authors.lastname: de Lima
authors.forename: Bruno G
authors.initials: BG
authors.lastname: Lucca
authors.forename: Antônio M J
authors.initials: AM
authors.lastname: Barbosa
authors.forename: Valdir S
authors.initials: VS
authors.lastname: Ferreira
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones / Q000032:analysis; D000455:Medicago sativa / Q000201:enzymology*; D008958:Models, Molecular; D010544:Peroxidases / Q000737:chemistry* / Q000378:metabolism; D010573:Pesticide Residues / Q000032:analysis*; D019800:Phenol / Q000737:chemistry; D011487:Protein Conformation; D015203:Reproducibility of Results; D013859:Thiocarbamates / Q000032:analysis*
chemical_list: D004800:Enzymes, Immobilized; D006873:Hydroquinones; D010573:Pesticide Residues; D013859:Thiocarbamates; D019800:Phenol; D006046:Gold; D010544:Peroxidases; C027971:thiodicarb; C031927:hydroquinone