Development of a Smartphone-Integrated Paper-Based Analytical Device for Cost-Effective, Rapid, and Sensitive Detection of Paracetamol in Pharmaceutical Products

The growing demand for rapid, low-cost, and portable analytical tools in pharmaceutical quality control has intensified interest in smartphone-assisted paper-based analytical devices (PADs). In this study, we report a novel PAD integrated with smartphone-based detection for the quantification of paracetamol in pharmaceutical products. The assay is based on a simple colorimetric reaction between paracetamol and sodium nitroprusside, producing a distinct green color with maximum absorbance at 700 nm. The color intensity, which correlates with paracetamol concentration, is quantified using red, green, and blue (RGB) values captured by a smartphone camera. The method demonstrated a linear response over the range of 0.4–3.6 mM, with a detection limit of 0.288 mM. Results showed a strong correlation with conventional UV–vis spectrophotometry, confirming analytical reliability. The device exhibited excellent reproducibility and minimal interference from common pharmaceutical excipients. Recovery studies on various commercial formulations—such as tablets, syrups, droppers, and ampoules—yielded recovery rates ranging from 94% to 109%. To the best of our knowledge, this is the first application of smartphone-based RGB color analysis on a paper-based platform for paracetamol detection. The method offers a robust, user-friendly, and affordable alternative for pharmaceutical quality assessment, particularly suitable for resource-limited and point-of-care settings.