A paper-based sensor with distance readout for rapid on-site screening of promethazine hydrochloride in beverages

The recreational abuse of promethazine hydrochloride, particularly when mixed with soft drinks, has raised significant public concern. Although well-established chromatographic methods are available for the analysis of promethazine hydrochloride, their reliance on sophisticated instrumentation limits rapid on-site screening in resource-limited settings. To address the public safety concerns arising from promethazine hydrochloride abuse, this study aims to develop an instrument-free paper-based sensor suitable for on-site rapid visual screening of promethazine hydrochloride in soft drinks.

Herein, we constructed a novel paper-based sensor with distance-readout mechanism. By functionalizing an aminated mesoporous silica nanoparticles nanolayer and a potassium persulfate sensing layer onto the paper channel, quantitative analysis was achieved via the migration distance of the pink band generated from the oxidation of promethazine hydrochloride. The results demonstrate that the sensor exhibits a good linear relationship within the promethazine hydrochloride concentration range of 100-700 mg/L, with a limit of detection (LOD) as low as 33 mg/L. The proposed method is successfully applied for the detection of promethazine hydrochloride in beverage samples, exhibiting excellent reproducibility, good selectivity, and stable storage at 4 °C for 45 days. Moreover, the detection results for real samples showed good consistency with those obtained by liquid chromatography.

Compared with other methods, our approach requires no complex equipment, enabling quantification using only a ruler. It offers significant advantages, including low cost, low sample consumption, and simple operation, thus providing a powerful and practical tool for on-site forensic screening and the monitoring of promethazine abuse in resource-limited settings.