Structural insight on thiourea doped graphene: An efficient electrochemical sensor for voltammetric detection of morphine in alcoholic and non-alcoholic beverages

Morphine (MO), a prime constituent of opium, is highly toxic and can alter various immune functions as well as disruption in the central nervous system. In this context, the present work focuses on the development of an electrochemical sensor based on thiourea (N and S atom) doped graphene for MO detection. The doping of nitrogen and sulphur (N and S) atoms effectively increases the active sites on graphene surface along with an increase in the electroactive surface area, causing faster electron transfer process. Various spectroscopic and microscopic characterization techniques such as Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy-energy dispersive X-ray (FESEM-EDX) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) endorsed the successful formation of N and S doped graphene (NSG). The electrochemical features of NSG modified glassy carbon electrode (NSG 4/GCE) were investigated through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Further, differential pulse voltammetry (DPV) measurements of NSG 4/GCE in the presence of MO were carried out to record the concentration dependent change in the redox current responses. The constructed sensor exhibited a dose dependent increase in DPV anodic peak current with a dynamic concentration range of 0.57 ​μgmL⁻¹ to 294 ​μgmL⁻¹ (at a potential of 0.37 ​V) and a detection limit of 0.26 ​μgmL⁻¹. Finally, the practical ability of the proposed electrochemical sensor for the determination of trace amount of morphine were evaluated in real samples such as soft and hard drinks. Therefore, the present electrochemical sensor based on NSG material as electrochemical interfaces could be a potential candidate for morphine detection in clinical settings and for forensic purpose.