Appendix XI G. Complete Extraction of Alkaloids

Complete extraction is indicated by the following tests.

Extraction with an aqueous or alcoholic liquid

After extracting at least three times with the liquid, add to 0.1 to 0.2 mL of the next portion, after acidifying with 2m hydrochloric acid if necessary, 0.05 mL of potassium tetraiodomercurate solution or, for solanaceous alkaloids, 0.05 mL of potassium iodobismuthate solution R1. No precipitate or turbidity is produced.

Extraction with an immiscible solvent

After extracting at least three times with the solvent, add to 1 to 2 mL of the next portion 1 to 2 mL of 0.1m hydrochloric acid, remove the organic solvent by evaporation, transfer the aqueous residue to a test tube and add 0.05 mL of potassium tetraiodomercurate solution or, for solanaceous alkaloids, 0.05 mL of potassium iodobismuthate solution R1 or, for emetine, 0.05 mL of iodinated potassium iodide solution. Not more than a very faint opalescence is produced.

Continuous extraction

After percolating for at least 2 hours, collect 1 to 2 mL of the effluent and carry out the procedure described under ‘Extraction with an aqueous or alcoholic liquid’ or ‘Extraction with an immiscible solvent’, as appropriate.