Antazoline Phosphate
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C17H19N3·H3PO4 363.35

1H-Imidazole-2-methanamine, 4,5-dihydro-N-phenyl-N-(phenylmethyl)-, phosphate (1:1).
2-[(N-Benzylanilino)methyl]-2-imidazoline phosphate (1:1) [154-68-7].
» Antazoline Phosphate contains not less than 98.0 percent and not more than 101.0 percent of C17H19N3·H3PO4, calculated on the dried basis.
Packaging and storage— Preserve in tight containers.
B: The RF value of the principal spot in the chromatogram of the Identification corresponds to that of Standard preparation A as obtained in the test for Chromatographic purity.
Melting range, Class Ia 741: between 194 and 198, with decomposition.
pH 791: between 4.0 and 5.0, in a solution (1 in 50).
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 0.5% of its weight.
Chromatographic purity—
Standard solutions— Dissolve USP Antazoline Phosphate RS in methanol, and mix to obtain a solution having a known concentration of 0.10 mg per mL. Quantitatively dilute with methanol to obtain 5 Standard solutions having the following compositions:
Dilution Concentration
(µg RS per mL)
(%, for comparison with test specimen)
A (1 in 2) 50 0.5
B (2 in 5) 40 0.4
C (3 in 10) 30 0.3
D (1 in 5) 20 0.2
E (1 in 10) 10 0.1
Test solution— Dissolve an accurately weighed quantity of Antazoline Phosphate in methanol to obtain a solution containing 10 mg per mL.
Identification solution— Dilute a portion of the Test solution quantitatively with methanol to obtain a solution containing 50 µg per mL.
Procedure— Apply separately 10 µL of the Test solution, 10 µL of the Identification solution, and 10 µL of each Standard solution to a suitable thin-layer chromatographic plate (see Chromatography 621), coated with a 0.25-mm layer of chromatographic silica gel mixture. Position the plate in a chromatographic chamber, and develop the chromatograms in a solvent system consisting of a mixture of ethyl acetate, methanol, and diethylamine (17:2:1) 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 solvent to evaporate. Examine the plate under short-wavelength UV light, and compare the intensities of any secondary spots observed in the chromatogram of the Test solution with those of the principal spots in the chromatograms of the Standard solutions. [note—Disregard any spots observed at the origins of the chromatograms.] No secondary spot from the chromatogram of the Test solution is larger or more intense than the principal spot obtained from Standard solution A (0.5%), and the sum of the intensities of all secondary spots obtained from the Test solution corresponds to not more than 1.0%.
Assay— Dissolve about 750 mg of Antazoline Phosphate, accurately weighed, in 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically, using a glass electrode and a calomel electrode containing a saturated solution of lithium chloride in glacial acetic acid (see Titrimetry 541). Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 36.34 mg of C17H19N3·H3PO4.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Elena Gonikberg, Ph.D.
Senior Scientist
(MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 1559