Assay—
Transfer an accurately measured volume of Oral Solution,equivalent to about 10mg of haloperidol,to a separator,and add 20mLof dilute hydrochloric acid (1in 20).Extract the solution with four 20-mLportions of ether,and wash the combined ether extracts with four 5-mLportions of dilute hydrochloric acid (1in 20).Discard the ether,and add the acid washings to the aqueous phase.Filter the aqueous phase through a pledget of cotton into a 50-mLvolumetric flask,add dilute hydrochloric acid (1in 20)to volume,and mix.Transfer 10.0mLof this solution to a 100-mLvolumetric flask,dilute with methanol to volume,and mix.Concomitantly determine the absorbances of this solution and of a solution of
USP Haloperidol RSin the same medium having a known concentration of about 20µg per mL,in 1-cm cells at the wavelength of maximum absorbance at about 245nm,with a suitable spectrophotometer,using a 1in 10solution of dilute hydrochloric acid (1in 20)in methanol as the blank.Calculate the quantity,in mg,of haloperidol (C
21H
23ClFNO
2)in each mLof Oral Solution taken by the formula:
0.5(C/V)(AU/AS),
in which
Cis the concentration,in µg per mL,of
USP Haloperidol RSin the Standard solution;
Vis the volume,in mL,of Oral Solution taken;and
AUand
ASare the absorbances of the solution from the Oral Solution and the Standard solution,respectively.