Belladonna Assay

Belladonna Assay

Assay of Belladonna Leaves.—" Belladonna Leaves, in No. 60 powder, ten grammes, Chloroform, Ether, Normal Sulphuric Acid V.S., Ammonia Water, Distilled Water, Tenth-normal Sulphuric Acid V.S., Fiftieth-normal Potassium Hydroxide V.S., Cochineal T.S., or lodeosin T.S., each, a sufficient quantity. Place the Belladonna Leaves in an Erlenmeyer flask, and add 50 Cc. of a mixture of chloroform 1 part and ether 4 parts (both by volume). After inserting the stopper securely allow the flask to stand ten minutes, then add 2 Cc. of ammonia water mixed with 3 Cc. of distilled water, and shake the flask well at frequent intervals during one hour. Then transfer as much as possible of the contents of the flask to a small percolator which has been provided with a pledget of cotton packed firmly in the neck and inserted in a separator containing 6 Cc. of normal sulphuric acid V.S. diluted with 20 Cc. of distilled water. When the liquid has passed through the cotton, pack the Belladonna Leaves firmly in the percolator with the aid of a glass rod, and having rinsed the flask with 10 Cc. of the chloroform-ether mixture, transfer the remaining contents of the flask to the percolator, by the aid of several portions (5 Cc.) of the chloroform-ether mixture, and continue the percolation with successive small portions of the same liquid (using in all 50 Cc.). Next, shake the separator well for one minute, after securely inserting the stopper, and when the liquids have completely separated, draw oft the acid solution into another separator. Add to the • chloroform-ether mixture 10 Cc. of sulphuric acid mixture of the same strength as that previously used, agitate well, and again draw off the acid solution into the second separator; repeat this operation once more, drawing off the acid solution as before; introduce into the acid solutions contained in the second separator a small piece of red litmus paper, then add ammonia water until the liquid is distinctly alkaline, and shake out with three successive portions of chloroform 15, 15, and 5 Cc.; collect the chloroform solutions in a beaker, place it on a waterbath containing warm water, and allow the chloroform to entirely evaporate. Dissolve the residue in 3 Cc. of ether, and let this also evaporate completely. To the alkaloidal residue add 3 Cc. of tenth-normal sulphuric acid V.S. and 5 drops of cochineal T.S. (or iodeosin T.S.), then titrate the excess of acid with fiftieth-normal potassium hydroxide V.S. Divide the number of cubic centimeters of fiftieth-normal potassium hydroxide V.S. used, by 5, subtract the quotient from 3 (the 3 Cc. of tenth-normal sulphuric acid V.S. taken), and multiply the remainder by 0.0287
and this product by 10 j the result will be' the percentage of total mydriatic alkaloids contained in the Belladonna Leaves." U. S.

Assay of Belladonna Root.—" The method to be employed is identical with that given under Belladonna Leaves, using ten grammes of Belladonna Root in No. 60 powder." U.S. W. Will published (A. Phys.) in 1888 the results of an investigation undertaken at the request of the Schering manufactory to determine why the proportion of hyoscyamine and atropine in a root seems to vary with the method of working, and reached the surprising conclusion that hyoscyamine can be changed into atropine under a variety of circumstances, such as fusion, action of weak soda solution (even at ordinary temperature), and of ammonia. The conversion of the optically active hyoscyamine into the optically inactive atropine, the alteration of fusing point in the two alkaloids, and of their double gold chloride salts, all confirm the results of the investigation. (Her. d. Chern. Ges., 1888, p. 1717.) The results were also confirmed by Schmidt. They were at first doubted by Ladenburg, but seem now to be admitted, the two alkaloids being stereoisomeric, and capable of such change.

Taken from...

The Dispensatory Of The United States Of America
By Dr. Geo. B.Wood And Dr. Franklin Bache.
Nineteenth Edition.
Thoroughly Revised, Largely Rewritten, And Based Upon The Eighth Decennial Revision Of The United States Pharmacopoeia Issued June 1, 1907.
Philadelphia And London
J.B. Lippincott Company