期刊
MICROCHEMICAL JOURNAL
卷 169, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.microc.2021.106569
关键词
Sulfite; Ascorbic acid; Carbon paste electrode; Metal-organic frameworks; Voltammetry; Food quality control
资金
- Alexander von Humboldt Foundation (Germany)
- German Academic Exchange Service (DAAD) [57214225]
The carbon paste electrode modified with the MIL-101(Cr) metal-organic framework showed improved charge transfer ability and increased real surface area, resulting in a more intense oxidation peak current of sulfite ions compared to the unmodified electrode. A linear relationship between the oxidation peak current and sulfite concentration was established, with a detection limit of 0.58 μM in the range of 2 μM-70 μM.
A carbon paste electrode modified with the MIL-101(Cr) metal-organic framework (MIL-101(Cr)-CPE) was prepared, characterized and assayed to the voltammetric detection of sulfite ions. Electrochemical impedance spectroscopy and cyclic voltammetry indicated a significant increase in charge transfer ability and real surface area (R-ct = 1.1 k Omega and S = 0.220 cm(2)) of the MIL-101(Cr)-CPE in comparison with the bare CPE (R-ct = 7.8 k Omega and S = 0.031 cm(2)). It was demonstrated by cyclic voltammetry that the oxidation of sulfite ions at the MIL-101 (Cr)-CPE follows an irreversible and diffusion-controlled mechanism. Also, the peak current of sulfite ions was 1.5-fold more intense on MIL-101(Cr)-CPE compared to the unmodified CPE. An analytical method was therefore developed, based on square wave voltammetry: under optimized experimental conditions, the MIL-101(Cr)-CPE electrode displayed a linear relationship between the oxidation peak current and the concentration of sulfite in the concentration range of 2 mu M-70 mu M, with a detection limit of 0.58 mu M (S/N = 3). The sensor was furthermore exploited for the simultaneous determination of sulfite and ascorbic acid, which gave well separated anodic peak at 0.35 V and 0.90 V (vs. Ag/AgCl, 3 M KCl), respectively. The proposed method was further used to determine both analytes in commercial wines, thus establishing its applicability as inexpensive analytical tool for quality control.
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