[Optimization of drying process for Scrophulariae Radix by multivariate statistical analysis]

To establish the suitable modern drying processing parameters for Scrophulariae Radix (SR). With reference to the traditional drying processing method of SR and the characteristics of modern drying equipment, the drying process for SR was simulated as the following three stages: temperature-controlled drying-tempering-temperature-controlled drying. Eighteen batches of SR samples were obtained by the drying methods after the orthogonal design experiment with seven factors namely temperature, wind speed, and target moisture for the first stage, tempering time and temperature, as well as temperature and wind speed for the second stage. UPLC-TQ-MS was applied for determination of nine target compounds including catalpol, harpagide, verbascoside, ferulic acid, angroside-C, aucubin, harpagoside, cinnamic acid and ursolic acid in those dried samples and another 19 batches of SR samples collected from genuine producing area. Principal Component Analysis (PCA) was performed, and total energy consumption was also taken into consideration for analysis and evaluation. Results showed that the optimal drying processing method for SR was as follows: drying temperature of 60 ℃, drying wind speed of 50 Hz, and 50% for target moisture in the first stage; 24 h for tempering time and temperature of 20 ℃ in the second stage; drying temperature of 60 ℃, and drying wind speed of 30 Hz in the third stage. The medicinal materials with optimized modern drying processing method were extremely similar to those collected from genuine producing area in the aspect of both external properties and target compounds, and they were in line with the 2015 version of "Chinese Pharmacopoeia" requirements. In addition, they could help to shorten the drying time and increase the efficiency of primary processing, and thus promote the normalization and standardization of primary drying processing for SR.