title: A novel amperometric sensor for ascorbic acid based on poly(Nile blue A) and functionalised multi-walled carbon nanotube modified electrodes.
abstract: A new type of modified electrode sensor for ascorbic acid has been prepared by deposition of multi-walled carbon nanotubes (MWCNT) and poly(Nile blue A) on the surface of glassy carbon electrodes. Nile blue A was electropolymerised either beneath (directly on glassy carbon) or onto the MWCNT layer by potential cycling in phosphate buffer solution at pH 6.0. Characterisation of the modified electrodes was carried out by cyclic voltammetry and electrochemical impedance spectroscopy. Quantitative determination of ascorbate was achieved by cyclic voltammetry and fixed potential amperometry in phosphate buffer solution at pH 5.3. The modified electrodes exhibited good sensitivity, wide linear range, a detection limit of 1.6 μM and good stability, showing that they can be used as sensors for ascorbic acid. There is no interference from compounds commonly found in clinical and pharmaceutical samples and the determination of ascorbic acid in commercial tablet samples was successfully performed.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
authors.forename: Dilek
authors.initials: D
authors.lastname: Kul
authors.forename: M Emilia
authors.initials: ME
authors.lastname: Ghica
authors.forename: Rasa
authors.initials: R
authors.lastname: Pauliukaite
authors.forename: Christopher M A
authors.initials: CM
authors.lastname: Brett
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis* / Q000737:chemistry; D002138:Calibration; D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods*; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010078:Oxazines / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D015203:Reproducibility of Results; D013499:Surface Properties; D013607:Tablets / Q000032:analysis / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D010078:Oxazines; D011108:Polymers; D013607:Tablets; C008619:Nile Blue; D001205:Ascorbic Acid