1 place 30 g of ground black pepper in a extraction thimble thimble and extracted with 300 mL 95% ethanol in a Soxhlet extractor for 2 h
2 the solution is concentrated to a volume of 10-15 mL by simple distillation or by use of a rotary evaporator
3 To 10 mL of a 10% solution of KOH in 95% ethanol contained in a 125 mL erlenmeyer flask add the concentrated pepper extract.
4 Heat the resulting solution and add water dropwise. A yellow precipitate forms, add water until no more solid appears to from and then allow the mixture to stand at least overnight