Sulfaquinoxaline

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Sulfaquinoxaline contains NLT 98.0% and NMT 101.0% of C₁₄H₁₂N₄O₂S, calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS 〈197〉 , Infrared Spectroscopy : 197K (CN 1-M  -2020)

Change to read:

B. SPECTROSCOPIC IDENTIFICATION TESTS 〈197〉 , Ultraviolet-Visible Spectroscopy : 197U (CN 1-MAY-2020)

Sample solution: 10 µg/mL in 0.01 N sodium hydroxide Acceptance criteria: Meets the requirements

3 ASSAY

PROCEDURE

Mobile phase: 2 g/L of monobasic ammonium phosphate in a mixture of acetonitrile, glacial acetic acid, tetrahydrofuran, ammonium hydroxide, and water (400:10:5:2:583). Pass through a filter of 0.5-µm or finer pore size.

Standard solution: 0.06 mg/mL of USP Sulfaquinoxaline RS in 0.01 N sodium hydroxide

Sample solution: 0.06 mg/mL of Sulfaquinoxaline in 0.01 N sodium hydroxide

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4-mm × 25-cm; packing L1 Flow rate: 1 mL/min

Injection size: 15 µL System suitability

Sample: Standard solution Suitability requirements

Tailing factor: NMT 1.2

Relative standard deviation: NMT 1.0% Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of sulfaquinoxaline (C₁₄H₁₂N₄O₂S) in the portion of Sulfaquinoxaline taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Sulfaquinoxaline RS in the Standard solution (mg/mL)

C_U = concentration of Sulfaquinoxaline in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–101.0% on the dried basis IMPURITIES

RESIDUE ON IGNITION 〈281〉: NMT 0.1%

ORGANIC IMPURITIES

Sample solution: 4 mg/mL, prepared as follows. Dissolve 400 mg of Sulfaquinoxaline in 4 mL of 1 N sodium hydroxide, dilute with methanol to 100 mL, and mix.

Standard solution A: 0.12 mg/mL of USP Sulfaquinoxaline Related Compound A RS in methanol Standard solution B: 0.04 mg/mL of sulfanilamide in methanol

Chromatographic system

(See Chromatography 〈621〉, Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 5 µL

Developing solvent system: Chloroform, methanol, and ammonium hydroxide (60:40:20)

Analysis: Separately apply each solution to the TLC plate, and proceed as directed in the chapter. When the solvent front has moved about three-fourths the length of the plate, remove the plate from the chamber, mark the solvent front, allow it to air-dry, and examine the plate under short-wavelength UV light.

Acceptance criteria: No spot corresponding to sulfaquinoxaline related compound A in the chromatogram of the Sample solution is more intense than the principal spot in the chromatogram of Standard solution A (NMT 3.0%); and no spot, other than the principal spot and the sulfaquinoxaline related compound A spot, in the chromatogram of the Sample solution is more intense than the principal spot in the chromatogram of Standard solution B (NMT 1.0%).

4 SPECIFIC TESTS

ACIDITY

Sample: 2 g

Analysis: Digest the Sample with 100 mL of water at about 70° for 5 min, cool to about 20°, and filter. Titrate 50 mL of the filtrate with 0.1 N sodium hydroxide VS to a pH of 7.0.

Acceptance criteria: NMT 0.2 mL is required

LOSS ON DRYING 〈731〉: Dry a sample at 105° for 4 h: it loses NMT 1.0% of its weight.

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers, protected from light.

LABELING: Label it to indicate that it is for veterinary use only.

USP REFERENCE STANDARDS 〈11〉

USP Sulfaquinoxaline Related Compound A RS

N¹,N²-Diquinoxalin-2-ylsulfanilamide.

C₂₂H₁₆N₆SO₂    428.50

USP Sulfaquinoxaline RS