ABSTRACT
The paper-based analytical device (PAD) was applied in this study to analyze the antioxidant activity of Danhong injection and its intermediates. First polycaprolactone was printed on the surface of a filter paper with a 3D printing device. The modified filter paper was then prepared using polycaprolactone and solid paraffin as the modifiers. The PAD was prepared after adding DPPH ethanol solution to the modified filter paper. Ascorbic acid solutions with different concentrations were used as the positive drug on PAD. After the occurrence of color reactions, the PAD was dried, and the data of color were collected by a cell phone. The color component G and grayscale were selected as the potential indices for measurement according to the values of determination coefficients, detection limits, and effective number of digits. Qualitative and quantitative analysis of Danhong injection and the concentrate of aqueous extract were realized with the PAD. Because no significant differences were observed between the results obtained using the two potential indices, the average values of these two were used for analysis, and the antioxidant activity of Danhong injection and the concentrate of aqueous extract was equivalent to ascorbic acid solutions of 3.7, 46 g·L⁻¹, respectively. The PAD method presented in this work can be a simple method to determine biological activities of Chinese medicines and their intermediates.
ABSTRACT
In this work, two algorithms (overlapping method and the probability-based method) for design space calculation were compared by using the data collected from extraction process of Codonopsis Radix as an example. In the probability-based method, experimental error was simulated to calculate the probability of reaching the standard. The effects of several parameters on the calculated design space were studied, including simulation number, step length, and the acceptable probability threshold. For the extraction process of Codonopsis Radix, 10 000 times of simulation and 0.02 for the calculation step length can lead to a satisfactory design space. In general, the overlapping method is easy to understand, and can be realized by several kinds of commercial software without coding programs, but the reliability of the process evaluation indexes when operating in the design space is not indicated. Probability-based method is complex in calculation, but can provide the reliability to ensure that the process indexes can reach the standard within the acceptable probability threshold. In addition, there is no probability mutation in the edge of design space by probability-based method. Therefore, probability-based method is recommended for design space calculation.