Sustainable Paper-Derived Laser-Induced Graphene Electrochemical Platform for Ultra-Sensitive Diazepam Detection in Forensic Investigations
Kasrin Saisahas, Asamee Soleh, Kritsada Samoson, Kiattisak Promsuwan, Jenjira Saichanapan, Sangay Wangchuk, Warakorn Limbut
Abstract
High Resolution Image Download MS PowerPoint Slide The use of benzodiazepines like diazepam (DZ) in drug-facilitated crimes necessitates the development of rapid, sensitive and portable detection methods. This study presents a sustainable, paper-derived laser-induced graphene (paper-LIG) electrochemical platform for ultrasensitive DZ detection in forensic investigations. The sensor was fabricated using a cellulose paper substrate treated with sodium tetraborate to enhance thermal stability, enabling efficient graphene conversion via optimized laser scribing. The physicochemical properties of paper-LIG were characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectrometry, Raman spectroscopy, Fourier-transform infrared spectrometry, and X-ray photoelectron spectroscopy. Additionally, the effects of working and auxiliary electrode sizes on electrochemical performance were evaluated. The resulting paper-LIG electrode exhibited excellent electrochemical performance, enabling direct DZ detection in beverage samples without complex pretreatment. Using an optimized voltammetric technique, the sensor achieved a wide linear range (1–1000 μmol L –1 ) and a low detection limit (0.4 μmol L –1 ). This platform demonstrated high selectivity, reproducibility (RSD 2.2%), and recovery (96.4–102.5%), confirming its reliability for forensic applications. Its low cost, scalability, and eco-friendliness make this sensor a promising tool for rapid on-site drug screening.