Electrode modified with reduced graphene oxide decorated with gold nanoparticles co-induced by laser for electrochemical alprazolam sensor

Abstract

A facile one-step laser-assisted approach to the co-induction of gold nanoparticles (AuNP) and reduced graphene oxide (rGO) is proposed. The resulting laser-induced (LI)-AuNP-rGO composite was drop-casted on a glassy carbon electrode (GCE). The fabricated LI-AuNP-rGO/GCE was developed for an electrochemical sensor to detect and quantify alprazolam, specifically in beverage samples. The LI-AuNP-rGO was morphologically characterised by scanning electron microscopy (SEM). The presence and content of gold was investigated via energy dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy. Comparative studies involved a pristine GO/GCE, a LI-rGO/GCE and a LI-AuNP-rGO/GCE. The electrochemical properties and behaviours of the modified electrode were characterised using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse-adsorptive cathodic striping voltammetry (DPAdCSV) was optimised and applied with the developed sensor, demonstrating good analytical performances in the adsorption of alprazolam and detection of the reduction current response. The response of developed sensor towards alprazolam under an optimal deposition potential of −100 mV vs. Ag/AgCl, and time for 200 s showed linearity in the concentration ranges of 1 µg L−1 to 0.10 mg L−1 and 0.10 to 8.0 mg L−1. The limit of detection was 0.3 µg-L−1 and the limit of quantification 0.9 µg-L−1. The developed sensor exhibited good and practical interference tolerance, excellent repeatability (<0.52 % RSD, n = 20) and reproducibility (<1.90 % RSD, n = 6). A spike and recovery study of alprazolam in beverage samples produced good results and demonstrated reliability to determine alprazolam in forensics applications. The easy preparation of the electrode modifying material could be used to prepare other electrochemical sensor materials.