Assay for emetine and cephaeline
Assay preparation
Transfer to a 150-mLbeaker about 200mg,accurately weighed,of Powdered Ipecac.Add 2mLof methyl sulfoxide,mix with a flattened stirring rod to assure complete wetting of the powder,and allow to stand for about 30minutes.Add 2mLof water and about 1g of sodium bicarbonate,and mix.
Calculate the quantity,in mg,of emetine in the portion of Powdered Ipecac taken by the formula:
0.05C(A283-A350)U/(A283-A350)S,
in which the parenthetic expressions are the differences in the absorbances of the solution of emetine from the Assay preparation(U)and the Standard preparation(S),respectively,at the wavelengths indicated by the subscripts,and Cis as defined in the Procedure.
Calculate the quantity,in mg,of cephaeline in the portion of Powdered Ipecac taken by the formula:
0.971(0.05C)(A283-A350)U/(A283-A350)S,
in which 0.971is the ratio of the molecular weight of cephaeline to that of emetine,the parenthetic expressions are the differences in the absorbances of the solution of cephaeline from the Assay preparation(U)and the Standard preparation(S),respectively,at the wavelengths indicated by the subscripts,and Cis as defined in the Procedure.