title: Carbon nanotubes for voltammetric determination of sulphite in some beverages.
abstract: In this work, a square-wave voltammetric method based on sulphite electrochemical reduction was developed for quantification of this preservative in commercial beverages. A carbon-paste electrode chemically modified with multiwalled carbon nanotubes was used as the working electrode. Under the optimised experimental conditions, a linear response to sulphite concentrations from 1.6 to 32 mg SO2 L(-1) (25-500 μmol L(-1) of sulphite), with a limit of detection of 1.0 mg SO2 L(-1) (16 μmol L(-1) of sulphite), was obtained. This method does not suffer interference from other common beverage additives such as ascorbic acid, fructose, and sucrose, and it enables fast and reliable sulphite determination in beverages, with minimal sample pretreatment. Despite its selectivity, the method is not applicable to red grape juice or red wine samples, because some of their components produce a cathodic peak at almost the same potential as that of sulphite reduction.
authors.affiliation: Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, Rua 20, 1600 Bairro Tupã, Ituiutaba, Minas Gerais CEP 38304402, Brazil. Electronic address: moreira_erika@hotmail.com.
authors.forename: Erika M
authors.initials: EM
authors.lastname: Silva
authors.affiliation: Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, Rua 20, 1600 Bairro Tupã, Ituiutaba, Minas Gerais CEP 38304402, Brazil. Electronic address: takeuchi@pontal.ufu.br.
authors.forename: Regina M
authors.initials: RM
authors.lastname: Takeuchi
authors.affiliation: Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, Rua 20, 1600 Bairro Tupã, Ituiutaba, Minas Gerais CEP 38304402, Brazil. Electronic address: alsantos@pontal.ufu.br.
authors.forename: André L
authors.initials: AL
authors.lastname: Santos
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry; D001628:Beverages / Q000032:analysis*; D055664:Electrochemical Techniques; D004566:Electrodes; D005632:Fructose / Q000737:chemistry; D057230:Limit of Detection; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013395:Sucrose / Q000737:chemistry; D013447:Sulfites / Q000032:analysis*; D027843:Vitis / Q000737:chemistry; D014920:Wine / Q000032:analysis
chemical_list: D037742:Nanotubes, Carbon; D013447:Sulfites; D005632:Fructose; D013395:Sucrose; D001205:Ascorbic Acid
keywords: Carbon-paste electrode; Coconut water; Fruit juice; Square-wave voltammetry; Sulphite reduction; White wine