ABSTRACT:

The rising incidence of sexual assault and the associated misuse of ketamine as a clandestine drug highlight the urgent need for rapid, portable, and reliable detection methods at the point of need. Herein, we report the development of a novel ionogel-based colorimetric sensor for ketamine detection, using the Morris reaction for a selective and visible response. Ionogels, emerging as innovative materials with tuneable chemical and physical properties, were integrated into a paper-based sensor platform, allowing facile fabrication, ease of handling, and on-site applicability. The sensor exhibited a clear colour change from green to purple in the presence of ketamine within 10 min, with a qualitative limit of detection of 4 mg mL⁻¹ and a working range of 4-12 mg mL⁻¹, covering concentrations commonly encountered in adulterated beverages. The device demonstrated satisfactory intra-day and inter-day precision (RSD ≤ 10 %) and could be reused at least once without significant loss of performance, enhancing cost-effectiveness and sustainability. This work represents the first application of ionogel-based sensors for ketamine detection and provides a promising foundation for the development of portable analytical tools aimed at preventing drug-facilitated sexual assault.