130 



DETERMINATION OF ALKALOID. 



Total extraction method. 



Into a 200 cc flask weigh 10 grams of the powdered drug, add about 75 cc of ether- 

 chloroform mixture (5 to 1 by volume), rotate and add 5 cc of 10 per cent ammonia 

 water, cork, shake well and often during two hours. 



Aliquot method. 



Into a 200 cc flask weigh 15 grams of the powdered drug, add 150 cc of ether- 

 chloroform mixture (5 to 1 by volume), cork and shake often for several minutes. Add 

 5 cc of ammonia water (10 per cent), shake frequently during two hours. Add 15 cc 

 of water, or sufficient to agglomerate the drug, shake, let settle a few minutes, and 

 then decant 100 cc of the clear solution into a graduated cylinder. * * * 



NOTE. Under both methods substitute "a few cubic centimeters" for the words "a 

 small portion," referring to the ether-chloroform rinsing. 



CINCHONA BARK. 



Method I. 

 



United States Pharmacopoeia VIII, page 102. Report total and ether-soluble 

 alkaloids. 



Method II. 



Total extraction, gravimetric. In extracting the drug let stand over night. 



The work on yellow and red cinchona and colchicum conn and root being quite 

 incomplete is not included in this report. The instructions should be followed as 

 strictly as possible, notes being taken during the work of any difficulties encountered, 

 objections to the methods, necessary or advisable modifications with the reasons 

 therefor, and any ambiguity or indefiniteness in the instructions should be indicated. 

 The value of collaborators' reports is much enhanced by this practice. (See tabula- 

 tion at close of report, p. 134.) 



For comparing in respect to their variability the results obtained by the different 

 methods from the several drugs, the average result for each method is taken as a basis, 

 and the proportion of all the results approaching within 10 per cent above or below 

 this average is given, and in addition the proportion approaching within 15 per cent 

 of the average. Reserving the question of absolute accuracy, results commonly vary- 

 ing over a range of more than 20 per cent in different hands can scarcely be described 

 as fairly uniform, nor can methods yielding such results be considered satisfactory 

 for the purposes of the official chemist. Only one operator has reported any dissatis- 

 faction with the behavior of cochineal as an indicator, though another has substituted 

 hematoxylin for it throughout. 



DETAILS OF MANIPULATION. 



The United States Pharmacopoeia assay methods generally direct that the initial 

 digestion of the drug with a solvent for the purpose of extracting the active principle 

 be accompanied by an indefinite amount of agitation. In certain cases continuous 

 agitation by means of suitable mechanism is alternatively directed, or preferred. The 

 expression "frequent shaking" is susceptible of various interpretations, and it would 

 be advisable to adopt the requirement of continuous agitation in all cases. 



A number of collaborators reported difficulty in decanting 100 cc of the solvent 

 mixture in extracting the drug by the aliquot method, and some were compelled to 

 use forcible expression or continue the assay with less than 100 cc, computing the 

 result on the basis of the aliquot part decanted. This occurred especially with bella- 

 donna leaves and cocoa leaves and is attributable to the coarseness of the samples. 

 In the Drug Division it was found practicable to obtain 100 cc by decanting the mix- 

 ture of drug and solvent as completely as possible into a small percolator provided 



