Carbohydrate and Lipid assays are routinely performed in many research and clinical fields. In this research, we used paper-based carbohydrate and lipid assays for screening the levels of carbohydrates in wine and soft drink samples and total lipids in dairy products. The carbohydrate was measured using Anthrone-sulfuric acid colorimetric assay on paper platform and the total lipid was measured using Sulpho-phospho vanillin colorimetric assay on paper platform. Paper device contained a test zone where reaction was allowed by adding standard/sample and reagent. Smartphone was used to capture an image of paper after reaction and the image was analyzed using ImageJ to measure the intensity and ultimately find the concentration of analyte. We measured total carbohydrates in 19 Nepali wines and 24 soft drinks sample. Similarly total lipids were measured in 13 dairy samples collected from local marts in Kathmandu valley. The total carbohydrate in wines and soft drinks and total lipids in dairy samples ranged from 0.36 to 78.67 mg/ml (mean=28.32±26.20 mg/ml), 0.25 mg/ml to 253.12 mg/ml (mean=167.86±63.85 mg/ml) and 2.11 mg/ml to 15.68 mg/ml (mean=6.56±5.08 mg/ml), respectively. We compared the measured value with the results obtained using conventional (spectrophotometric) method. We found that the two methods had very strong positive correlation (r2 > 0.8). The Bland and Altman Analysis of carbohydrate results in wines and soft drinks showed a negative bias of paper device with spectrophotometer (-24.51 mg/ml; 95% limits of agreement, -48.93 to -0.09; n=19 and -18.63 mg/ml; 95% limits of agreement, -39.69 to 2.43; n=24, respectively) and that of lipid results showed a good agreement with a positive bias of paper device with spectrophotometer (0.69 mg/ml; 95% limits of agreement, -0.93 to 2.31; n=13). The results of the assay (B&A analysis and p<0.05) provides evidence for the potential of paper devices for quantitative analyses. We demonstrate that these paper-based assays may provide inexpensive alternative to quantify carbohydrates and lipids as it does not require expensive equipment, trained personnel, and require very less (in µl) volume of reagent/sample.
