The dried roots of Inula racemosa were pulverized and sieved with 100 ~ 200 mesh. The herb powder was placed into a glass bottle. Ultrasound-assisted extraction was carried out in an ultrasonic cleaner RK102H (Bandelin sonorex, Germany). The powder of Inula racemosa was extracted three times under the following conditions: the ratio of material to solvent was 10:1, undergoing ultrasonic treatment 30 minutes at 25 °C, 100 kHz /450 W.31 Before large extraction, a small-scale extraction experiments were carried out: 95% ethanol and ethyl acetate as the extractive solutions was investigated, respectively. The extraction efficiency was evaluated according to the percent content of AL and IS contained in the dried roots of Inula racemosa and calculated …show more content…
The silver ion TLC was prepared through the following procedure: Silver nitrate was dissolved in 10 ml of distilled water. This aqueous solution of silver nitrate was absolutely mixed with 9 g of silica gel (10 ~ 40 μm particles). Then, a 10 × 5 cm TLC plate was coated with the above slurry and activated for 1 h at 90 °C before use. They were immediately transferred into a desiccator in dark for storage after cooling. 32 100 μL of afore-prepared sample solution and the mixed reference standard were diluted 100 times with ethyl acetate. 50 μL of these dilution solutions were separated on the TLC plate coated with SNISG. The plate was developed with petroleum ether: ethyl acetate (4:1) and the movement of solvent was usually controlled at 1 cm from the upper edge. After completion, the plate was dried until no solvent smell remained. It was sprayed with an ethanol solution containing 10% sulfuric acid, and heated at an infra-red drier until obvious color came up, as shown in Fig.2 (B.ab). Simultaneously, the amount of silver nitrate in the impact of isolative effect was investigated with the sample procedure, as shown in Fig.2