Design and Optimization of Colorimetric Paper-Based Analytical Device for Rapid Detection of Allopurinol in Herbal Medicine

Figure 4

Design of paper-based analytical device: (a) support base, (b) Whatman filter paper content Folin-Ciocalteu reagent, (c) Whatman filter paper content p-DAB reagent, (d) Whatman filter paper content Tollens reagent.