Single-use dye displacement colorimetry assay based on molecularly imprinted polymers: Towards fast and on-site detection of xylazine in alcoholic beverages

The use of the veterinary tranquilizer xylazine as an adulterant poses a major health problem in the world. Involuntary consumption of this drug (e.g. spiked beverages and suicidal attempts) leads to loss of consciousness and even death. In this work, a probe for the fast, visual detection of xylazine in alcoholic beverages is proposed. The technology is based on xylazine-specific molecularly imprinted polymers that were loaded with methylene blue to generate a dye-displacement assay. The assay displayed high selectivity when evaluated against common compounds present in beverages. Optimal assay conditions were found at pH ≥ 7 and alcohol contents <15 v/v%. Furthermore, the assay was evaluated in a real gin and tonic sample and displayed a linear regime of 1.5–4 mM and a LOD of 1.36 mM. Implementation of the assay in a portable device resulted in a much faster xylazine detection (under 30 s) in a spiked gin & tonic sample.