title: Biosensor based on multi-walled carbon nanotubes paste electrode modified with laccase for pirimicarb pesticide quantification.
abstract: This study focused on the development of a sensitive enzymatic biosensor for the determination of pirimicarb pesticide based on the immobilization of laccase on composite carbon paste electrodes. Multi-walled carbon nanotubes (MWCNTs) paste electrode modified by dispersion of laccase (3%, w/w) within the optimum composite matrix (60:40%, w/w, MWCNTs and paraffin binder) showed the best performance, with excellent electron transfer kinetic and catalytic effects related to the redox process of the substrate 4-aminophenol. No metal or anti-interference membrane was added. Based on the inhibition of laccase activity, pirimicarb can be determined in the range 9.90 × 10(-7) to 1.15 × 10(-5) mol L(-1) using 4-aminophenol as substrate at the optimum pH of 5.0, with acceptable repeatability and reproducibility (relative standard deviations lower than 5%). The limit of detection obtained was 1.8 × 10(-7) mol L(-1) (0.04 mg kg(-1) on a fresh weight vegetable basis). The high activity and catalytic properties of the laccase-based biosensor are retained during ca. one month. The optimized electroanalytical protocol coupled to the QuEChERS methodology were applied to tomato and lettuce samples spiked at three levels; recoveries ranging from 91.0 ± 0.1% to 101.0 ± 0.3% were attained. No significant effects in the pirimicarb electroanalysis were observed by the presence of pro-vitamin A, vitamins B1 and C, and glucose in the vegetable extracts. The proposed biosensor-based pesticide residue methodology fulfills all requisites to be used in implementation of food safety programs.
authors.affiliation: REQUIMTE, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. Bernardino de Almeida 431, 4200-072 Porto, Portugal.
authors.forename: Thiago M B F
authors.initials: TM
authors.lastname: Oliveira
authors.forename: M
authors.initials: M
authors.lastname: Fátima Barroso
authors.forename: Simone
authors.initials: S
authors.lastname: Morais
authors.forename: Pedro
authors.initials: P
authors.lastname: de Lima-Neto
authors.forename: Adriana N
authors.initials: AN
authors.lastname: Correia
authors.forename: Maria B P P
authors.initials: MB
authors.lastname: Oliveira
authors.forename: Cristina
authors.initials: C
authors.lastname: Delerue-Matos
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D002219:Carbamates / Q000032:analysis*; D055664:Electrochemical Techniques; D004566:Electrodes; D005504:Food Analysis / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D059022:Food Safety; D006801:Humans; D007306:Insecticides / Q000032:analysis*; D042845:Laccase / Q000737:chemistry*; D018545:Lactuca / Q000737:chemistry; D057230:Limit of Detection; D018551:Solanum lycopersicum / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry; D011743:Pyrimidines / Q000032:analysis*; D015203:Reproducibility of Results; D013379:Substrate Specificity
chemical_list: D002219:Carbamates; D007306:Insecticides; D037742:Nanotubes, Carbon; D011743:Pyrimidines; C011994:pirimicarb; D042845:Laccase