Graphene quantum dot/Ag-based metal-organic framework nanocomposite modified carbon paste electrode for determination of diazepam in real samples

This research describes a nanocomposite comprising graphene quantum dot (GQD) and silver-based metal-organic framework (Ag-MOF), GQD-Ag-MOF, which was utilized as modifier in order to introduce of a new electrochemical sensor for quantification of diazepam. The GQD-Ag-MOF nanocomposite was characterized using FTIR, XRD, DLS, FESEM and TEM, and was applied to make a modified carbon paste electrode (CPE). Based on the cyclic voltammetry (CV) results, it was confirmed that the GQD-Ag-MOFznanocomposite modified CPE (GQD-Ag-MOF/CPE) has well electrocatalytic activity towards the diazepam oxidation. Also, the catalytic electron transfer rate constant (k') and electron transfer coefficient (a) for the diazepam oxidation at the surface of GQD-Ag-MOF/CPE were investigated. The species diffusion coefficient and studying analytical performance of the proposed sensor were also evaluated using chronoamperometry. By the square wave voltammetry (SWV), the linear response range of ۱.۰-۰.۱۱.۱ μM of diazepam and a limit of detection of ۱.۱. μM were obtained. Eventually, the introduced sensor was satisfactorily utilized for quantification of these substances in medicinal and biological samples.

Keywords:

Diazepam , Silver-based Metal-organic frameworks , Graphene quantum dots.