THE ALUMNI JOURNAL 127 



QUANTITATIVE DETERMINATION OF PHENOL- 

 PHTHALEIN IN GALENICALS. 



Konstantin Kollo {Apoth. Ztg., xxiv, p. 383) gives the following 

 methods of quantitatively determining phenolphthalein in galenicals: 



1. — Tablets or pastilles are reduced to fine powder; confections, 

 containing tamarind or prunes, are thoroughly dried, and reduced to 

 as fine a powder as possible. A weighed portion of the material is 

 then introduced into a separatory funnel the neck of which is closed 

 by a plug of cotton, and percolated with pure acetone (boiling at 

 56 — 570 c ) until a drop is no longer colored red by potassium hydro- 

 xide solution. The acetone percolate is then evaporated on the 

 water-bath, and the residue dried at 100° C. and weighed. 



2. — Instead of using acetone, the comminuted substance is exhausted 

 with 8-per cent, sodium hydroxyde solution, and the phenolphthalein 

 precipitated by adding acetic acid. The precipitated is collected on 

 a small filter, washed with water, then stirred with acetone, the 

 mixture transfessed to a weighed vessel, and then waporated, dried at 

 100° C, and weighed. 



3. — The solution of the substance in 10—15 Cc. of 8-per cent, 

 sodium-hydroxide solution (and which should contain 0.4—0.6 Gm. 

 phenolphthalein), as obtained in 2. is introduced into an Erlenmeyer 

 flask, and to it is added, in small quantities at a time, an iodine 

 solution prepared from 2 Gm. iodine, 3 Gm. potassium iodide, and 

 20 Cc. water. The color of the solution passes from red into blue, 

 and finally, when sufficient of the iodine solution is added, into yellow. 

 Concentrated hydrochloric is now added to precipitate the tetraido- 

 phenolphthalein formed. The latter is than collected on a weighed 

 filter washed first with 90-per cent, alcohol, then with ether, and is 

 finally dried at 100° C. and weighed. In order to avoid any slight 

 loss due to a slight solubility of the compound in alcohol and ether, it 

 is advisable to employ liquids that have first been saturated with 

 iodophenolphthalein. The centrifuge, too, may be advantageously 

 employed for washing the precipitate, using tubes of 60 — 80 Cc. 

 capacity. The centrifuged powder adheres tightly to the walls of 

 the vessels, and is weighed in these. 1 Gm. tetraiodophenolphthalein, 

 C6H4-(C02).(C6H2l20H)„, corresponds to 0.3869 Gm. phenolph- 

 thalein. 



4.— In this method the phenolphthalein is exhausted as detailed 

 under 1, and is then acetylized with acetic anhydride. The isolated 



