A microfluidic paper-based device for on-site colorimetric detection of scopolamine in beverages, pharmaceuticals,...

Drug-facilitated sexual assault is a major public health and forensic concern, frequently involving central nervous system depressants such as scopolamine. This tropane alkaloid is especially hazardous due to its strong amnestic, sedative, and hallucinogenic effects, combined with its lack of color, odor, and taste. Despite its toxicological importance, there are still few methods available for the rapid on-site detection of scopolamine. Therefore, portable, low-cost analytical tools capable of detecting scopolamine in a variety of matrices at the point-of-need are still lacking. Here, we developed an autonomous microfluidic paper-based analytical device for the rapid detection of scopolamine in pharmaceuticals, plant extracts, and beverages. The device is based on Scott's colorimetric reaction, in which Cobalt(II) thiocyanate forms a visible pink-to-blue complex with scopolamine under acidic conditions. The system consists of a cellulose substrate sandwiched between hydrophilic and hydrophobic pressure-sensitive adhesive layers and a poly(methyl methacrylate) cover, enabling capillary-driven fluid transport and direct visual readout. Calibration studies demonstrated a concentration-dependent color change, achieving limits of detection of 0.13 mg mL^-1 for pure scopolamine and 0.11 mg mL^-1 for commercial formulations such as Buscapina®. The device was tested in a wide range of alcoholic and non-alcoholic beverages and produced a clear response in extracts of Datura stramonium and Atropa belladonna. This microfluidic paper-based device provides a fast, reliable, and easy-to-use approach for the on-site detection of scopolamine and related compounds. Its low cost, portability, and visual readout make it particularly suitable for forensic screening and public health protection. The platform represents a significant advancement toward practical point-of-need detection of drug-facilitated assault agents.