Laboratory of Analytical Chemistry, Faculty of Science, The University of Yaounde 1, P.O. Box 812, Yaounde, Cameroon.
Laboratory of Analytical Chemistry, Faculty of Science, The University of Yaounde 1, P.O. Box 812, Yaounde, Cameroon; Department of Chemistry, University of Douala, P.O. Box 24157, Douala, Cameroon.
Talanta. 2021 Jan 15;222:121550. doi: 10.1016/j.talanta.2020.121550. Epub 2020 Aug 29.
The present work reports the development of a low-cost and reliable differential pulse adsorptive stripping voltammetric procedure for the detection of diquat (DQ) in water, using a glassy carbon electrode (GCE) modified with β-cyclodextrin (β-CD)/Natural hydroxyapatite (NHAP) composite material. The structural characterization of the natural hydroxyapatite and its modified counterpart was achieved using several techniques including X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Thermal Analysis. By comparing the physico-chemical characteristics of hydroxyapatite material before and after reaction with β-CD, all of these techniques have demonstrated the successful grafting process of β-CD on the surface hydroxyl groups of hydroxyapatite, using citric acid (CA) as cross linker. The electrochemical features and permeability properties of the obtained materials, coated as thin film onto the GCE surface were characterized using ion exchange multisweep cyclic voltammetry. The β-cyclodextrin modified hydroxyapatite (NHAP-CA-β-CD) was evaluated as electrode modifier for DQ sensing. The electroanalytical procedure followed two steps: the chemical preconcentration of DQ under open-circuit conditions, and the differential pulse voltammetric detection of the preconcentrated pesticide. Various experimental parameters likely to influence the sensibility of electrode were fully investigated and optimized. A linear calibration curve for DQ in the concentration range of 5 × 10 - 4.5 × 10 mol L was obtained at GCE/NHAP-CA-β-CD, with a detection limit of 4.66 × 10 mol L (DL = 3S/M). The proposed method was successfully applied to the determination of DQ in spring water.
本工作报道了一种使用玻碳电极（GCE）修饰的β-环糊精（β-CD）/天然羟基磷灰石（NHAP）复合材料，发展了一种用于检测水中二噁烷（DQ）的低成本、可靠的差分脉冲吸附溶出伏安法。通过 X 射线衍射、傅里叶变换红外光谱和热分析等多种技术对天然羟基磷灰石及其修饰物的结构特征进行了表征。通过比较羟基磷灰石材料在与β-CD 反应前后的物理化学特性，所有这些技术都证明了β-CD 成功地接枝到羟基磷灰石表面的羟基上，使用柠檬酸（CA）作为交联剂。采用离子交换多扫循环伏安法对涂覆在 GCE 表面的所得材料的电化学特性和渗透性进行了表征。用β-环糊精修饰的羟基磷灰石（NHAP-CA-β-CD）作为电极修饰剂用于 DQ 传感。电分析程序分为两步：在开路条件下对 DQ 进行化学预浓缩，以及对预浓缩的农药进行差分脉冲伏安检测。充分研究和优化了可能影响电极灵敏度的各种实验参数。在 GCE/NHAP-CA-β-CD 上，DQ 在 5×10 - 4.5×10 - 4 mol L 的浓度范围内得到线性校准曲线，检测限为 4.66×10 - 4 mol L（DL=3S/M）。该方法成功应用于测定泉水样品中的 DQ。
