Noroozifar Meissam, Khorasani-Motlagh Mozhgan, Tavakkoli Hamed
Analytical Research Laboratory, Department of Chemistry, University of Sistan & Baluchestan, Zahedan, P. O. Box 98155-147, Iran.
Anal Sci. 2011;27(9):929-35. doi: 10.2116/analsci.27.929.
The present work describes the construction of a new modified graphite-multiwall carbon nanotube paste electrode by casting the appropriate mixture of tetraheptylammonium iodide-iodine as a new modifier. The modified paste electrode was used for the determination of ascorbic acid (AA) in a phosphate buffer solution (pH 2.0). When compared to activated carbon, a graphite and multiwall carbon nanotube paste electrode containing a new modifier, the proposed modified paste electrode not only shifted the oxidation potential of AA towards a less-positive potential but also enhanced its oxidation peak current. Further, the oxidation of AA was highly stable at the modified paste electrode. The optimum analytical conditions were sought. The current response of AA increases linearly while increasing its concentration from 5.6 × 10(-5) to 1.2 × 10(-2) M with a correlation coefficient of 0.9991; the detection limit (3σ) was found to be of 3.6 × 10(-5) M. The present modified paste electrode was also successfully used for the determination of AA in the presence of common interference compounds. The present modified electrode was successfully demonstrated towards the determination of AA in pharmaceutical and food samples.
本工作描述了通过浇铸四庚基碘化铵 - 碘的适当混合物作为新型改性剂来构建新型改性石墨 - 多壁碳纳米管糊电极。该改性糊电极用于测定磷酸盐缓冲溶液（pH 2.0）中的抗坏血酸（AA）。与活性炭、含有新型改性剂的石墨和多壁碳纳米管糊电极相比，所提出的改性糊电极不仅将AA的氧化电位向更正电位移动，还增强了其氧化峰电流。此外，AA在改性糊电极上的氧化高度稳定。寻求了最佳分析条件。当AA的浓度从5.6×10⁻⁵增加到1.2×10⁻² M时，其电流响应呈线性增加，相关系数为0.9991；检测限（3σ）为3.6×10⁻⁵ M。本改性糊电极还成功用于在常见干扰化合物存在下测定AA。本改性电极成功用于测定药物和食品样品中的AA。
