Identification—
Dilute a volume of Injection with 0.1Nhydrochloric acid to obtain a solution having a concentration of about 20µg of hydroxyzine hydrochloride per mL:the UVabsorption spectrum of this solution exhibits maxima and minima at the same wavelengths as that of a 1in 50,000solution of
USP Hydroxyzine Hydrochloride RSin 0.1Nhydrochloric acid,concomitantly measured.
Assay and limit of 4-chlorobenzophenone—
Mobile phase—
Adjust about 1000mLof
Buffer No.1(see
Phosphate Buffers and Other Solutionsin the section
Media and Diluents,under
Antibiotics—Microbial Assays á81ñ)with 10Npotassium hydroxide to a pHof 6.6.To about 35volumes of this solution add about 65volumes of methanol,mix,and degas.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation—
Dissolve accurately weighed quantities of
USP Hydroxyzine Hydrochloride RSand 4-chlorobenzophenone in
Mobile phase,and dilute quantitatively with
Mobile phaseto obtain a solution having known concentrations of about 250µg of
USP Hydroxyzine Hydrochloride RSand 0.5µg of 4-chlorobenzophenone per mL.Protect this solution from light.
Assay preparation—
Transfer an accurately measured volume of Injection,equivalent to about 125mg of hydroxyzine hydrochloride,to a 50-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Pipet 10mLof this solution into a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Protect this solution from light.
Chromatographic system
(see
Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the
Standard preparation,and record the peak responses as directed under
Procedure:the tailing factors for the 4-chlorobenzophenone and hydroxyzine peaks are not more than 2.5,the resolution,
R,between the 4-chlorobenzophenone and hydroxyzine peaks is not less than 2.0,and the relative standard deviation for replicate injections of the
Standard preparationis not more than 2.0%.The relative retention times are about 0.75for 4-chlorobenzophenone and 1.0for hydroxyzine.
Procedure—
Separately inject equal volumes (about 20µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of hydroxyzine hydrochloride (C
21H
27ClN
2O
2·HCl)in each mLof the Injection taken by the formula:
0.5(C/V)(rU/rS),
in which
Cis the concentration,in µg per mL,of
USP Hydroxyzine Hydrochloride RSin the
Standard preparation;
Vis the volume,in mL,of Injection taken;and
rUand
rSare the hydroxyzine peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.The ratio of the response of the 4-chlorobenzophenone peak to that of the hydroxyzine peak obtained from the
Assay preparationdoes not exceed the corresponding ratio of peak responses obtained from the
Standard preparation(0.2%).