Acid value 401 —Dissolve about 1 g of the purified Storax, accurately weighed, in 50 mL of neutralized alcohol, add 0.5 mL of phenolphthalein TS, and titrate with 0.5 N sodium hydroxide VS: the acid value is between 50 and 85 for Levant Storax and between 36 and 85 for American Storax.

Saponification value 401 —Place about 2 g of the purified Storax, accurately weighed, in a 250-mL flask, mix it with 50 mL of solvent hexane, add 25.0 mL of 0.5 N alcoholic potassium hydroxide VS, and allow the mixture to stand for 24 hours with frequent agitation. Then add 0.5 mL of phenolphthalein TS, and titrate the excess alkali with 0.5 N hydrochloric acid VS: the saponification value thus determined is between 160 and 200.

Cinnamic acid— Add about 2 g of the purified Storax, accurately weighed, to 25 mL of 0.5 N alcoholic potassium hydroxide, and boil the mixture for 1 hour under a reflux condenser. Add 0.5 mL of phenolphthalein TS, neutralize with 0.5 N sulfuric acid, and evaporate the alcohol on a steam bath. Dissolve the residue in 50 mL of water, and shake the solution with 20 mL of ether. Shake the separated ether with 5 mL of water, adding the washing to the water solution, and reject the ether extract. Add to the water solution 10 mL of diluted sulfuric acid, and shake with four 20-mL portions of ether. Wash the combined ether extracts with 5 mL of water, rejecting the water washing, transfer to a flask, and distill off the ether. Add to the residue 100 mL of water, and boil the mixture vigorously for 15 minutes under a reflux condenser. Filter while hot, and allow the filtrate to cool to about 25: white crystals of cinnamic acid separate. Collect and dry the cinnamic acid by vacuum filtration. Repeat the extraction of the residue twice by boiling each time under a reflux condenser, as previously described, with the filtrate from the preceding crystallization, and collect the additional cinnamic acid in the same crucible. Finally wash the cinnamic acid with two 10-mL portions of ice-cold water, dry at 80, and weigh. The weight of the cinnamic acid so obtained is not less than 25.0% of the weight of purified Storax taken. A portion of the acid recrystallized from hot water melts between 134 and 135.

(Official January 1, 2007)