*2.1. Chemicals and Reagents*

The standard products, including gelsemine (CAS#: 1803-14-9, purity: 99.28%), koumine (CAS#: 1807-14-8, purity: 99.84%) and humantenmine (CAS#: 2106-30-8, purity: 99.63%), were purchased from Must (Chengdu, China). A PRS cation exchange column (500 mg, 3 mL) was purchased from Welch (Shanghai, China). A Waters Oasis HLB column (3 cc, 60 mg, 30 μm) was purchased from Waters (Shanghai, China). Methanol and acetonitrile of HPLC grade were purchased from Merck Co. (Darmstadt, Germany). Ammonium dihydrogen phosphate, phosphoric acid and ammonia were purchased from Kemiou (Tianjin, China). Ultra-pure water with a resistivity of <18.2 MΩ cm was prepared from a Milli-Q water purification system (Millipore, Bedford, MA, USA). The blank honey sample was purchased from various supermarkets. Thirty honey samples were collected from farmers' markets in Hunan, Guizhou, Yunnan and Fujian Provinces from January 2022 to May 2022.
