XXIX. DRUGS. 



Caffein and Acetanilid in Mixtures. 



1 preparation of sample and solution.— tentative. 



(a) If the sample is already in powder form, rub thoroughly in a mortar and 

 keep in a tightly corked tube or flask. Powders in paper, cachet or capsule con- 

 tainers are frequently of such fineness as to require little further trituration except 

 to produce a uniform product. On a tared 5.5 cm. filter weigh 0.3-0.5 gram of the 

 sample or, if preferred, an amount equal to, or a multiple of, the average unit dose 

 (previously ascertained by weighing collectively 20 or more such doses), wash wath 

 successive 5-10 cc. portions of the chloroform (30-50 cc. are usually sufficient) until 

 the extraction is complete as indicated by the absence of any residue after evapora- 

 tion of a small portion of the last washing. Collect the solution in a 200 cc. Erlen- 

 meyer flask, connect the flask with a condenser by means of a cylindrical Kjeldahl 

 connecting bulb^ and distil until the volume is reduced to about 10 cc. 



(b) If the caffein is present in the citrated form, or the composition of the mix- 

 ture precludes complete extraction as directed in (a), weigh out the desired amount, 

 transfer to a Squibb separatory funnel, add 50 cc. of the chloroform and 20 cc. of 

 water, shake vigorously and, after clearing, draw off the lower layer through a 

 small, dry filter into a 200 cc. Erlenmeyer flask. In the case of coated tablets and 

 pills, ascertain their average weight, powder in a mortar and weigh out for each 

 determination an amount equivalent to one or more tablets or pills. Repeat the 

 extraction twice, using 50 cc. portions of the chloroform for each extraction. Dis- 

 til the combined chloroform extracts to about 10 cc. 



(C) In the case of dilute alcoholic solutions, evaporate a measured quantity on 

 a steam bath until most of the alcohol has been expelled, or take an aliquot of 

 the residue from an alcohol determination; transfer to a separatory funnel by pour- 

 ing and rinsing with a minimum of water so that the final volume does not greatly 

 exceed 20 cc, and then, in order to avoid any loss of acetanilid by hydrolysis during 

 evaporation, add a little solid sodium bicarbonate and a drop of acetic anhydrid. 

 (Should the preparation contain alkaloids, acidify with a few drops of dilute sul- 

 phuric acid immediatelj' after acetylization to retain such basic material in solu- 

 tion.) Add 50 cc. of the chloroform, shake vigorously and, after clearing, draw off 

 the chloroform layer through a filter into a 200 cc. Erlenmeyer flask. Repeat the 

 extraction twice, using 50 cc. portions of the chloroform for each extraction, and 

 distil the combined chloroform washings to a volume of about 10 cc. 



CAFFEIN AND ACETANILID.— TENTATIVE. 



2 REAGENTS. 



(a) Standard hromid-hromate solution. — Dissolve 50 grams of potassium hydroxid 

 in a small quantity of water, add a slight excess of bromin, dilute with water to dis- 

 solve any separated salts, boil to expel excess of bromin and dilute to 1 liter. Stand- 

 ardize the solution against recrystallized acetanilid and adjust the solution so that 

 1 cc. is equivalent to 5 or 10 mg. of acetanilid as desired. 



(b) C/iZoro/or??}.— Redistilled and residue-free. All corks used in the distillation 

 should be treated previously with chloroform. 



351 



