Simultaneous Electrochemical Analysis of Hydrophilic and Lipophilic Antioxidants in Bicontinuous Microemulsion

• Published in: Analytical chemistry (Washington) Vol. 87; no. 3; pp. 1489 - 1493
• Main Authors: Kuraya, Eisuke, Nagatomo, Shota, Sakata, Kouhei, Kato, Dai, Niwa, Osamu, Nishimi, Taisei, Kunitake, Masashi
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.02.2015
• Subjects: alpha-Tocopherol - chemistry; Analytical chemistry; Antioxidants; Antioxidants - chemistry; Ascorbic Acid - chemistry; Biochemistry; Coffee - chemistry; Electrochemical Techniques; Electrodes; Emulsions - chemistry; Extraction; Food Analysis; Hydrophobic and Hydrophilic Interactions; Indium tin oxide; Lipids - chemistry; Metal oxides; Microemulsions; Nanostructure; Olive Oil; Oxidation-Reduction; Plant Oils - chemistry; Polyphenols; Quantitative analysis; Tin Compounds - chemistry
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac5044576

Qualitative and quantitative analyses of hydrophilic and lipophilic antioxidants, such as polyphenols, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), in which water and oil phases coexisted bicontinuously on a microscopic scale. Hydrophilic and lipophilic antioxidants were individually monitored in the same BME solution using a hydrophilic indium tin oxide (ITO) electrode and a lipophilic fluorinated nanocarbon film electrode (F-ECR), respectively. The combination of well-balanced BME and extremely biased electrodes, such as ITO and F-ECR, in terms of hydrophilic–lipophilic balance allowed us to achieve individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without extraction. Furthermore, the antioxidant activities of functional liquid foods, such as coffee and olive oil, were also evaluated by means of electrochemical measurements in BME solutions containing analytes in concentrations of several percent. The technique we propose provides a very simple, rapid, easily serviceable, and highly reproducible analysis and can be extended to a wide range of analytes and media.