Objective To establish a method for the rapid determination of total flavonoids in tartary buckwheat by cerium dioxide/multi-walled carbon nanotubes/acetylene black (CeO2/MWCNTs/AB) nano-electrochemical sensor. Methods The modified material and these nanoelectrochemical sensors were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behavior of rutin on the electrode surface was systematically investigated via CV. Critical parameters were optimized, including electrolyte type, pH, modifier ratio, coating volume, accumulation time and scan rate. Results One pair of well- defined redox peaks were observed at the potential of 0.54 V and 0.57 V, which indicated that the electrochemical oxidation and reduction reaction of flavonoid was reversible. The experimental conditions were optimized, the results as follows: B-R solution with pH 2.0 as the electrolyte solution, VCeO2/MWCNTs:Vacetylene black as 1:3, amounts of modified material, 12 μL, enrichment time as 9 min. At these conditions, the oxidation peak current of flavonoid linearly increased with its concentration, Ip=0.793C+3.508 (r2=0.998), and the limit of detection was 6.5×10-8 mol/L. The developed method was used to determinate total flavonoids content of tartary buckwheat, the recoveries were in the range of 99.46%-102.15%, the results were superior to ultraviolet-visible spectrophotometry. Conclusion The method is feasible for the rapid and accurate determination of total flavonoids in food with the advantages such as simple pretreatment time saving and convenience, low detection cost, high sensitivity and good accuracy.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |