Tolazoline Hydrochloride
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C10H12N2·HCl 196.68

1H-Imidazole,4,5-dihydro-2-(phenylmethyl)-,monohydrochloride.
2-Benzyl-2-imidazoline monohydrochloride [59-97-2].
»Tolazoline Hydrochloride contains not less than 98.0percent and not more than 101.0percent of C10H12N2·HCl,calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.Store at 25,excursions permitted between 15and 30.
Identification—
A:Infrared Absorption á197Mñ.
B: The RFvalue of the principal spot in the chromatogram of the Identification corresponds to that of Standard solution A,as obtained in the test for Chromatographic purity.
Melting range á741ñ: between 172.0and 176.0.
Loss on drying á731ñ— Dry it in vacuum over silica gel for 4hours:it loses not more than 0.2%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
Chromatographic purity—
Standard solutions— Dissolve USP Tolazoline Hydrochloride RSin methanol,and mix to obtain Standard solution Ahaving a known concentration of 100µg per mL.Quantitatively dilute with methanol to obtain Standard solutions,designated below by letter,having the following compositions:
Standard solution Dilution Concentration
(µg RSper mL)		 Percentage
(%,for
comparison
with test specimen)
A undiluted 100 0.5
B 4in 5 80 0.4
C 3in 5 60 0.3
D 2in 5 40 0.2
E 1in 5 20 0.1
Test solution— Dissolve an accurately weighed quantity of Tolazoline Hydrochloride in methanol to obtain a solution containing 20mg per mL.
Identification solution— Quantitatively dilute a portion of the Test solutionwith methanol to obtain a solution containing 100µg per mL.
Detection reagent— Prepare (1)a solution of 0.5g of potassium iodide in 50mLof water,and (2)a solution of 1.5g of soluble starch in 50mLof boiling water.Just prior to use,mix 10mLof each solution with 3mLof alcohol.
Procedure— Apply separately 5µLof the Test solution,5µLof the Identification solution,and 5µLof each Standard solutionto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Position the plate in a chromatographic chamber,and develop the chromatograms in a solvent system consisting of a mixture of methanol and ammonium hydroxide (95:5)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the plate to dry under a current of warm air for at least 30minutes.Expose the plate to chlorine gas for not more than 5minutes,and air-dry until the chlorine has dissipated (about 15minutes).Spray the plate with Detection reagent,and immediately compare the intensities of any secondary spots observed in the chromatogram of the Test solutionwith those of the principal spots in the chromatograms of the Standard solutions:the sum of the intensities of all secondary spots obtained from the Test solutioncorresponds to not more than 1.0%.
Assay— Dissolve about 300mg of Tolazoline Hydrochloride,accurately weighed,in 100mLof glacial acetic acid;add 25mLof mercuric acetate TS;and titrate with 0.1Nperchloric acid VS,determining the endpoint potentiometrically (see Titrimetry á541ñ),using a calomel–glass electrode system.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nperchloric acid is equivalent to 19.67mg of C10H12N2·HCl.
Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
USP28–NF23Page 1947
Pharmacopeial Forum:Volume No.29(5)Page 1588
Phone Number:1-301-816-8305