Sustainable stencil-printed unmodified graphite–rosin electrode for electrochemical detection of ketamine in forensic samples

ABSTRACT Ketamine (KET) is a clinically used anesthetic with a high potential for abuse. Recreational and improper use of this substance pose significant health risks, including psychological, cardiovascular, neurotoxic, and dependency-related effects. However, there is currently no official and reliable method for its preliminary detection. Therefore, the development of rapid, selective, and simple analytical methods for KET detection is of great interest in both clinical and forensic contexts. In this study, we present an unprecedented application of rosin ‒ a natural, eco-friendly resin derived from Pinus species ‒ as a green binding additive in graphite-based conductive formulations for the fabrication of stencil-printed electrodes (graphite-pine rosin composite stencil electrode, GPC-SE). The GPC-SE fabrication process was optimized, and ideal conditions for reversibility and performance were established with a composition of 45% rosin, 55% graphite, and 5 mL of solvent. The resulting sensor was characterized by Raman spectroscopy, scanning electron microscopy, and electrochemical techniques. The GPC-SE combined with square-wave voltammetry exhibited wide linear range (50-500 μmol L −1 ) in Britton-Robinson buffer solution (pH 8, 50 mmol L −1 ), high sensitivity and low limits of detection (3.3 μmol L −1 ) and quantification (10.1 μmol L −1 ). The developed GPC-SE provided satisfactory reproducibility (RSDs <1.0% for Eₚ and <7% for Iₚ) and accuracy based on addition-recovery experiments on seized samples, beverages, and spiked biological samples. These findings demonstrate the applicability of the method in both forensic and clinical scenarios as rapid, reliable, and sustainable strategy for on-site identification of KET.