Oxytocin extraction: Take 100g of dried *Pterocarya stenoptera* powder and 30g of quartz powder, place them in a ball mill, add distilled water, and extract four times using the same method. The amount of distilled water added is 1.4L twice and 1.3L twice. Each extraction lasts 45 minutes, followed by centrifugation. Collect the liquid, and extract the residue again. Combine the four extracts to obtain the oxytocin solution. That is: dried *Pterocarya stenoptera* powder [water, ball mill] → oxytocin extract (chromatographic separation).
Add 1500g of pre-treated synthetic zeolite to 20L of 0.25% acetic acid solution, stir, and pour into an exchange column. When the acetic acid solution drops to 2-3cm above the zeolite surface, add the extract. Collect the white turbid liquid (mainly containing oxytocin, due to its pI 7.7, while vasopressin has a pI 10.9, making it easily adsorbed as a positive ion) at an appropriate flow rate. When the extract level drops to the zeolite surface, immediately add distilled water and continue collecting the turbid liquid until all the liquid has flowed out. The turbid solution was adjusted to pH 3.5 with glacial acetic acid, rapidly heated to 95°C in a water bath and held for 3 minutes, then rapidly cooled and refrigerated overnight. The process was: oxytocin extract [HAc, synthetic zeolite column] → turbid solution [HAc, heated] → separation solution (adsorption, elution). The next day, the refrigerated solution was filtered, and 10% bentonite slurry (3 mL per 100 mL) was added to the filtrate with stirring. Adsorption was carried out for 1 hour, followed by centrifugation. The supernatant was checked with sulfosalicylic acid test solution; no precipitation indicated complete adsorption. If incomplete adsorption occurred, the adsorption was repeated, and the two bentonite slurry precipitations were combined. The bentonite was eluted four times with 1% acetic acid (1.6 L, 1.4 L, 1.2 L, and 0.8 L respectively). Each eluent was heated to 80°C, chlorobutanol was added, and the temperature was further increased to 95°C, then rapidly cooled to 25°C. The eluents were filtered or centrifuged, and the four filtrates were combined to determine the potency and vasopressin limit. That is, the preparation of refrigerated liquid [filtration] → filtrate [soap clay slurry] → adsorbent [1% HAc] → eluent oxytocin injection.
