A: Transfer a volume of Oral Solution,equivalent to about 12mg of triprolidine hydrochloride,to a 125-mLseparator,add 25mLof water,then add 4mLof sodium hydroxide solution (1in 2),and mix.Add 10mLof cyclohexane,shake,allow the phases to separate completely,and discard the aqueous layer.Transfer 8mLof the cyclohexane solution to a glass-stoppered,25-mLconical flask,evaporate on a steam bath with the aid of a current of air to dryness,and continue to heat the flask for about 1minute after the solvent has completely evaporated.Cool,add 2mLof cyclohexane,and mix:the IRabsorption spectrum of the cyclohexane solution so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Triprolidine Hydrochloride RS.

B: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

Mobile phase— Prepare a suitable degassed and filtered mixture of alcohol and ammonium acetate solution (1in 250)(17:3).

Standard preparation— Dissolve an accurately weighed quantity of USP Triprolidine Hydrochloride RSin 0.01Nhydrochloric acid,and dilute quantitatively and stepwise with 0.01Nhydrochloric acid to obtain a solution having a known concentration of about 0.05mg of anhydrous USP Triprolidine Hydrochloride RSper mL.

Assay preparation— Transfer an accurately measured volume of Oral Solution,equivalent to about 2.5mg of triprolidine hydrochloride,to a 50-mLvolumetric flask,dilute with 0.01Nhydrochloric acid to volume,and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4.2-mm ×25-cm column that contains packing L3.The flow rate is about 1.5mLper minute.Chromatograph five replicate injections of the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2.0%;and the tailing factor is not more than 1.5.

Procedure— Separately inject equal volumes (about 10µL)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 triprolidine hydrochloride (C19H22N2·HCl·H2O)in the portion of Oral Solution taken by the formula: in which 332.88and 314.86are the molecular weights of triprolidine hydrochloride monohydrate and anhydrous triprolidine hydrochloride,respectively;Cis the concentration,in mg per mL,calculated on the anhydrous basis,of USP Triprolidine Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.