Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry.
Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry.
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DOI：
10.3762/bjnano.3.45
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发表时间：
2012
影响因子：
3.1
通讯作者：
Vicente-Beckett V
中科院分区：
文献类型：
--
作者：
Kumar S;Vicente-Beckett V
多壁碳纳米管用于修饰玻碳电极的表面以增强其电活性。 Nafion 用于将碳纳米管固定在电极表面上。使用修饰电极开发了一种通过方波伏安法 (SWV) 分析抗坏血酸 (AA) 的分析方法。抗坏血酸在改性玻碳电极上的氧化显示出 315 mV 的峰值电位，比在裸露（未改性）电极上观察到的低约 80 mV。峰值电流大约是裸电极响应的三倍。峰值电流的重复测量显示出良好的精度（3% rsd）。峰值电流随着抗坏血酸浓度的增加而增加（动态范围 = 0.0047–5.0 mmol/L），并表现出良好的线性（R2 = 0.994）。检测限为1.4 μmol/L AA，定量限为4.7 μmol/L AA。将该修饰电极应用于四种品牌市售橙汁产品中抗坏血酸含量的测定。所有测试品牌的测量含量与产品标签声明非常吻合 (96–104%)。对加标橙汁样品的回收率测试显示出良好的回收率 (99–104%)。通过基于吸光度检测的高效液相色谱 (HPLC) 进行平行实验，验证了 SWV 方法的可靠性。对两种方法获得的市售橙汁样品的平均AA含量进行统计比较，发现没有显着差异（P = 0.05）。
Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA) by square-wave voltammetry (SWV). The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified) electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd). Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047–5.0 mmol/L) and displayed good linearity (R2 = 0.994). The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96–104%) with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99–104%). The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC) with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05).
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