304 



THE ALUMNI JOURNAL. 



NEW METHOD FOR QUANTITATIVE 

 ISOLATION OF ALKALOIDS. 



The following is the method proposed 

 by Dr. Kippenberger in the Zeitschrift 

 fiir analyt. Chemie. The alkaloids are 

 precipitated from their solution even to 

 the last trace, by a solution of iodine in 

 potassium iodide. To remove any pro- 

 tein or foreign substances which might 

 be carried along with the precipitate, it 

 is dissolved in acetone and any free pre- 

 cipitated iodine removed by treatment 

 with caustic soda or potassa. From the 

 colorless solution the alkaloid is removed 

 by shaking with ether or chloroform. 

 The details are as follows: The alkaloid 

 is extracted from the substance to be ex- 

 amined by means of acidulated water; 

 this solution is then neutralized or made 

 feebly alkaline and at once precipitated 

 with a concentrated solution of iodine in 

 potassium iodide. The precipitate, after 

 allowing to settle for awhile, is collected 

 on a (water dissolves the double salt), fol- 

 lowed by a small volume of acetone, 

 which dissolves the precipitate, yielding 

 a brown-colored solution. This solution 

 is treated with a small amount of an 

 alkali hydroxide followed at once with 

 an acid in slight excess, diluting with 

 water. The resulting colorless solution 

 which contains the alkaloids in form of 

 acid salts is carefully warmed on a water 

 bath to drive off the acetone (which boils 

 at 56° C) , then a few drops of solution 

 of sodium hyposulphite are added while 

 still warm, to remove any brown colora- 

 tion. To the liquid a slight excess of 

 sodium carbonate solution is added and 

 the whole shaken with cloroform for the 

 extraction of the alkaloid. It is to be 

 understood that if morphine or narcein is 

 present it is to be removed by extraction 

 with amyl alcohol. Glucosides do not 

 react with iodo-potassium iodide, hence 

 this method serves for the separation of 

 the two classes of bodies. 



Kippenberger recommends this meth- 

 od in place of Keller's for the assay of 



alkaloidal drugs, extracts, etc., the pro- 

 cedure being as follows: The extract 

 which is to be assayed is dissolved in 

 warm acidulated water, filter if neces- 

 sary, when cold render it almost neutral 

 and then precipitate the alkaloids with 

 the solution of iodine in potassium iodide. 

 This latter solution is best prepared by 

 dissolving from 12.7 to 20 gm. of iodine 

 with about 60 gm. of potassium iodide in 

 a liter of water. After settling, the pre- 

 cipitate is collected upon a filter, washed 

 with cold water. As soon as the wash 

 water runs through clear, the precipitate 

 is dissolved in the smallest possible 

 quantity of acetone, which is treated 

 alternately with a solution of caustic 

 alkali and an acid, then diluting with 

 water, after which it is shaken with pe- 

 troleum ether (30°— 50° C.) The addi- 

 tion of caustic alkali solution serves to 

 combine the free iodine as iodide and 

 iodate, and the acid decomposes the 

 iodate into free iodine and a salt of the 

 alkali. The agitation with petroleum 

 ether serves to remove any impurities 

 that may be present, also most of the 

 acetone, however not even traces of the 

 alkaloid are taken up by this solvent. 

 The petroleum ether also serves to re- 

 move the traces of iodine, which are 

 liberated on the addition of the acid to 

 the iodate. This extraction by agitation 

 is repeated twice and the mixed petro- 

 leum ether washings are shaken with a 

 small quantity of acid diluted water, 

 which is returned to the original solu- 

 tion. The mixed acid aqueous solutions 

 are slightly warmed to remove the traces 

 of dissolved acetone and petroleum ether, 

 then a few drops of — solution of sodium 

 hyposulphite added, followed by an ex- 

 cess of sodium carbonate solution, the 

 whole being then shaken with either 

 chloroform, ether or a mixture of both, 

 which extracts the alkaloid. Emul- 

 sions of the chloroform frequently result 

 during agitation; these may be separated 

 by warming or adding one-third the vol- 

 ume of ether. — Pharvi. Era. 



