Ammonium acetate

Apatinib (purity >98.0%) was purchased from Nanjing Chemlin chemical industry co., LTD. (Nanjing, China). Verapamil (purity >98.0%) was obtained from Raw material medicine reagent co., LTD. (Nanjing, China), which was used as internal standard (IS). The acetonitrile and methanol were HPLC grade and purchased from Fisher Scientific (United States). Ultra-pure water was acquired from Watsons (Hongkong, China). Formic acid (FA) was purchased from DaMao chemical reagent factory (Tianjin, China). Ammonium acetate was obtained from Tianjin Guangfu Technology Development Co., LTD. (Tianjin, China). Other reagents and chemicals were analytical grade. Drug-free heparinized rat plasma was freshly collected from Sprague-Dawley (SD) rats in our laboratory and stored at −20°C before use.

The poplar (air-dry density 0.48 g/cm³), Paulownia (air-dry density 0.32 g/cm³), Chinese fir (air-dry density 0.47 g/cm³), and larch (air-dry density 0.40 g/cm³) were provided by Heilongjiang Yabuli Wood Industry Co., Ltd. The moisture content of the wood specimen was 4%. The butyl titanate, glacial acetic acid, acetylacetone and ammonium acetate were purchased from the Tianjin Guangfu Fine Chemical Research Institute.