Smartphone based colorimetric method for determination of memantine via schiff's base reaction with ascorbic acid

The smartphone-based colorimetric approach has emerged as a powerful analytical tool with broad applications, enabling fast and cost-effective measurements, eco-friendly operation with low energy demand, and reasonable analytical performance. In this work, a simple and eco-friendly colorimetric method was developed for the determination of memantine (MEM) in pharmaceutical dosage forms. In this approach, MEM reacts with ascorbic acid to produce a pink-colored product exhibiting two absorption maxima (λ_max) at 386 nm and 530 nm. The color response was captured using a smartphone camera and analyzed digitally with ImageJ software, where the extracted color intensity values were correlated with MEM concentration. A conventional spectrophotometric method relying on the absorbance at 386 nm was also established. Both methods exhibited excellent linearity over the concentration range of 5.0-50.0 µg/mL. The smartphone-based method showed a limit of detection (LOD) of 0.45 µg/mL and limit of quantitation (LOQ) of 1.36 µg/mL, while the spectrophotometric method exhibited a LOD of 0.0615 µg/mL and LOQ of 0.19 µg/mL. The greenness of the methods was evaluated using the newly introduced EPPI tool, a comprehensive metric that assesses greenness, applicability, and analytical performance. The results are presented as pie charts and numerical scores. The total scores for the smartphone and colorimetric approaches were 84.4 and 82.4, respectively, indicating the superiority of the smartphone-based method in terms of sustainability and practical applicability.