Catalysis and Materials Laboratory, Department of Chemistry, National Institute of Technology Karnataka, Surathkal, Mangalore, Karnataka, 575025, India.
Mikrochim Acta. 2019 Aug 26;186(9):646. doi: 10.1007/s00604-019-3745-6.
Amino-functionalized graphene quantum dots (NH-GQD) are described for the amperometric determination of oxalic acid. The NH-GQD were synthesized via a hydrothermal method using hexamethylenetetramine as the source for nitrogen. The average particle size of the GQD is ∼30 nm, which is also supported by TEM. Electrochemical analysis of the NH-GQD-GO composite on a glassy carbon electrode at pH 7.4 showed a faint reduction peak at -0.6 V vs. SCE, which was enhanced in the presence of oxalic acid. This variation in cathodic current density is an interesting deviation from the usually studied anodic current density for the electrochemical sensors. This is also supported by cyclic voltammetry and time-based amperometric measurements. The electrode has a linear response in the 0.5-2.0 mM and 2.0-55 mM oxalate concentration ranges and a 50 μM detection limit (at S/N = 3). The electrode was successfully applied to the determination of oxalate in spiked urine samples. Graphical abstract Schematic representation of the fabrication of amino-functionalized graphene quantum dots and graphene oxide composite coated on glassy carbon electrode for utilizing the electro-reduction peak in cyclic voltammetry at around -0.6 V for the quantitative determination of oxalic acid.
氨基功能化石墨烯量子点（NH-GQD）可用于测定草酸的电流测定法。NH-GQD 通过水热法合成，使用六亚甲基四胺作为氮源。GQD 的平均粒径约为 30nm，这也得到 TEM 的支持。在 pH 7.4 下，在玻碳电极上对 NH-GQD-GO 复合材料进行电化学分析，在相对于 SCE 的-0.6V 处显示出微弱的还原峰，在存在草酸的情况下增强。这种阴极电流密度的变化与通常研究的电化学传感器的阳极电流密度有很大的不同。这也得到了循环伏安法和基于时间的安培测量的支持。该电极在 0.5-2.0mM 和 2.0-55mM 草酸盐浓度范围内具有线性响应，检测限为 50μM（S/N=3）。该电极成功应用于测定加标尿样中的草酸盐。
