Research on the Clarity of Xiaoshi Oral Liquid - 1 --- The digestion oral solution is prepared using 12g forsythia, 12g hawthorn, Divine Comedy (6g), Magnolia (8g), dried tangerine peel (8g), and Radish Seed (1.2g). These ingredients are boiled and then subjected to alcohol precipitation, yielding per ml a legal system of traditional Chinese medicine oral liquid containing 1g of active ingredients. This oral liquid is primarily used for poor appetite and loss of appetite due to embolism. After heat sterilization at 13 liquid degrees, cloudiness and even flocculent precipitates often appear. A reference method to adjust the pH was employed to improve the clarity of the liquid herbal product; reagents used were of analytical grade; herbs were identified by the Quality Supervision and Inspection Division of Xi’an Medical Pharmaceutical Factory.
2.2.1 Preliminary Analysis of Oral Liquid Sediment: After heat sterilization, the opacity of the products in the sediment was filtered, dried at 60°C, and weighed. Results showed that each 10ml of liquid contained 0.1~0.2g of precipitate (n=10). Samples were taken into five test tubes, each with 0.5g of dried sediment added to 10ml of water, shaken, and adjusted with sodium hydroxide or hydrochloric acid to pH values of 2, 4.6, 8, and 10, respectively. Results indicated that when the pH was greater than 6, as the pH increased, the precipitate dissolved faster, and the solution color changed from yellow to brown to reddish-brown. When the pH was 6 or less, as the pH decreased, the solubility of the sediment also decreased, suggesting that the sediments contain acidic substances.
2.2 Oral Solution Changes During Placement: The stock solution of the digestion oral liquid (pH about 3.9) was placed and then had its pH adjusted using sodium hydroxide. The changes in the pH of the liquid over time are shown in Table 1.
2.3 Moist Heat Sterilization Effects on Oral Liquid pH: For one liquid sample (950 417), chlorine oxide and sodium were added to adjust the pH to 7.21. After 24 hours of placement, the pH was measured at 6.21. After potting and 100°C sterilization, the pH decreased by 1.38. For another liquid sample (950 423), the pH was adjusted to 8.79. After 24 hours of placement, the pH was 7.73. After 100°C 30-minute sterilization, the pH dropped to 5.11, indicating bacterial removal caused the pH value to decrease by 2.62. This suggests that heat sterilization affects the pH value of the oral solution.
2.4 Impact of Moist Heat Sterilization on Oral Solution Clarity: The pH values of the oral solutions were regulated to 4.0, 5.0, 6.0, 7.0, and 8.0. After 24 hours of placement, the pH values were re-measured. Sodium hydroxide and hydrochloric acid were used to adjust the original pH values back to their initial states, followed by 100°C 60-minute sterilization. Observations showed that above pH 6, the clarity improved; below pH 5, as the pH value decreased gradually, turbid flocculent precipitates formed.
2.5 Stability Experiments of Oral Liquid: Digestion oral liquid (pH adjusted to 8.52) was placed for 24 hours and then adjusted to pH 6.10, 7.0, and 8.08, respectively. Each was filled into 10ml ampoules and sterilized at 100°C for 60 minutes. Post-sterilization, the pH values were 4.82, 5.15, and 5.43, respectively. After sterilization, lamp inspections confirmed required clarity. Then, the samples were placed at 37°C and 0°C for three months, and upon re-examination, they remained clear.
3 Discussion and Conclusions: Regulating the pH of the digestion oral solution between 6 and 8 improves the product's clarity. The Xiaoshi Oral Liquid extract has a complex composition of traditional Chinese medicine. Further study is needed regarding why the pH decreases after placement or heat sterilization.