title: Determination of chlorogenic acid in coffee using a biomimetic sensor based on a new tetranuclear copper(II) complex.
abstract: A new tetranuclear copper(II) complex which mimics the active site of catechol oxidase was synthesized and characterized by IR, CHN, electronic spectroscopic and (1)H NMR methods. The title complex [Cu(2)(mu-OH)(bpbpmp-NO(2))](2)[ClO(4)](2) was employed in the construction of a novel biomimetic sensor and used in the determination of chlorogenic acid by square wave voltammetry. The performance and optimization of the resulting biomimetic sensor were studied in detail. The best response of this sensor was obtained for 75:15:10% (w/w/w) ratio of the graphite powder:nujol:Cu(II) complex, 0.1 mol L(-1) phosphate buffer solution (pH 7.0), with frequency, pulse amplitude, and scan increment at 30 Hz, 100 mV, and 3.0 mV, respectively. The chlorogenic acid concentration was linear in the range of 5.0x10(-6) to 1.45x10(-4)mol L(-1) (r=0.9985) with a detection limit of 8.0x10(-7)mol L(-1). This biomimetic sensor demonstrated long-term stability (250 days; 640 determinations) and reproducibility, with a relative standard deviation of 10.0%. The recovery study of chlorogenic acid in coffee samples gave values from 93.2% to 106.1% and the concentrations determined showed good agreement when compared with those obtained using capillary electrophoresis at the 95% confidence level.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, CEP 88040-900 Florianópolis, SC, Brazil.
authors.forename: Mirella Lucas
authors.initials: ML
authors.lastname: de Carvalho
authors.forename: Murilo
authors.initials: M
authors.lastname: Santhiago
authors.forename: Rosely A
authors.initials: RA
authors.lastname: Peralta
authors.forename: Ademir
authors.initials: A
authors.lastname: Neves
authors.forename: Gustavo Amadeu
authors.initials: GA
authors.lastname: Micke
authors.forename: Iolanda Cruz
authors.initials: IC
authors.lastname: Vieira
mesh_terms: D040761:Biomimetic Materials / Q000032:analysis* / Q000737:chemistry*; D002021:Buffers; D002726:Chlorogenic Acid / Q000032:analysis*; D003069:Coffee / Q000737:chemistry*; D003300:Copper / Q000032:analysis* / Q000737:chemistry*; D004563:Electrochemistry; D019075:Electrophoresis, Capillary; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010710:Phosphates; D015203:Reproducibility of Results
chemical_list: D002021:Buffers; D003069:Coffee; D010710:Phosphates; D002726:Chlorogenic Acid; D003300:Copper