碳纳米管-石墨烯修饰电极测定洋葱中槲皮素的含量

Determination of Quercetin in Onions by MWCNT/RGO Modified GCE

制备了在水中有良好分散性的氧化石墨烯/碳纳米管复合材料,并用紫外-可见光谱法、透射电镜及热重分析等方法对其进行表征。将此材料滴涂于GCE表面,经电化学方法还原制得MWCNT/RGO修饰电极。用循环伏安法和差示脉冲伏安法研究了槲皮素在此修饰电极上的电化学行为。结果表明:此修饰电极对槲皮素的氧化具有良好的电催化活性,能用于槲皮素的灵敏测定。在pH 4.2的乙酸盐缓冲介质中,开路富集150s,50mV·s-1的扫描速率下,槲皮素浓度在0.1~75μmol·L^(-1)范围内与其氧化峰电流呈线性关系,检出限(3S/N)为4.05×10-2μmol·L^(-1)。取粉碎的洋葱样品,用无水乙醇提取10h置于上述缓冲溶液中进行DPV扫描。所得提取液中槲皮素的测定值与高效液相色谱法测定值接近。加标回收率在82.1%~87.4%之间。

A composite of graphene oxide （GO） and MWCNT with high dispersivity in water was prepared and characterized by UV-vis spectrometry, TEM and themogravimetry. The composite was dropping-plated on the surface of GLEE, and the GO were reduced electrochemically to give MWCNT/RGO modified GCE. Electrochemical behavior of quercetin （QCT） at the modified electrode was studied by CV and DPV. Good electrocatalytic activity toward the oxidation of QCT was observed at the modified electrode, thus giving capability of its application as a working electrode in the sensitive DPV determination of QCT. In acetate buffer medium of pH 4. 2, and under the condition of enrichment for 150 s with opencircuit and at scanning rate of 50 mV · s-1 , l.inear relationship between values of anodic peak current and concentration of QCT was obtained in range from 0. 1 to 75 μmol · L-1 , with detection limit （3s/N） of 4. 05 X 10-2 μmol ·L-1. In determination of QCT in onion, the powdered sample were taken and extracted with absolute alcohol for 10 h. The extract were taken and added with the buffer solution and then the DPV determination was operated as described above. The result of QCT in an onion sample was found to be close to the value by HPLC. The recoveries were observed in the range of 82.1-87. 4%.