Dichlorphenamide

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

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

DOWNLOAD PDF HERE

C₆H₆Cl₂N₂O₄S₂    305.14

1,3-Benzenedisulfonamide, 4,5-dichloro-;

4,5-Dichloro-m-benzenedisulfonamide;

4,5-Dichlorobenzene-1,3-disulfonamide     CAS RN®: 120-97-8; UNII: VVJ6673MHY.

1 DEFINITION

Dichlorphenamide contains NLT 98.0% and NMT 101.0% of dichlorphenamide (C₆H₆Cl₂N₂O₄S₂), calculated on the dried basis.

2 IDENTIFICATION

2.1 A. Spectroscopic Identification Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U

Sample solution: 0.1 mg/mL of Dichlorphenamide in 0.4 mg/mL of sodium hydroxide solution

Analysis: To 10 mL of the Sample solution add 0.1 mL of hydrochloric acid.

Acceptance criteria: It exhibits absorption maxima at 295 ± 2 nm and at 286 ± 2 nm. The ratio A₂₉₅/A₂₈₆ is between 0.90 and 1.00.

2.2 B. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197A or 197M

3 ASSAY

3.1 Procedure

Solution A: 2.4 g/L of monobasic sodium phosphate and 2.8 g/L of dibasic sodium phosphate in water

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: Acetonitrile and water (1:1)

Standard solution: 0.5 mg/mL of USP Dichlorphenamide RS in Diluent

Sample solution: 0.5 mg/mL of Dichlorphenamide in Diluent

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: LC
• Detector: UV 280 nm
• Column: 4.6-mm × 15-cm; 2.7-µm packing L1
• Flow rate: 0.4 mL/min
• Injection volume: 10 µL

System suitability

• Sample: Standard solution
• Suitability requirements
• Tailing factor: NMT 2.0
• Relative standard deviation: NMT 0.73%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of dichlorphenamide (C₆H₆Cl₂N₂O₄S₂) in the portion of Dichlorphenamide taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response of dichlorphenamide from the Sample solution

rₛ = peak response of dichlorphenamide from the Standard solution

Cₛ = concentration of USP Dichlorphenamide RS in the Standard solution (mg/mL)

Cᵤ = concentration of Dichlorphenamide in the Sample solution (mg/mL)

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

4 IMPURITIES

4.1 Residue on Ignition 〈281〉: NMT 0.2%

Change to read:

4.2 Organic Impurities

Solution A, Solution B, Diluent, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.002 mg/mL of USP Dichlorphenamide RS in Diluent

Sample solution: 2 mg/mL of Dichlorphenamide in Diluent

System suitability

• Sample: Standard solution
• Suitability requirements
• Tailing factor: 0.8–1.5
• Relative standard deviation: NMT 10.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each individual impurity in the portion of Dichlorphenamide taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × (1/F) × 100

rᵤ = peak response of each individual impurity from the Sample solution

rₛ = peak response of dichlorphenamide from the Standard solution

Cₛ = concentration of USP Dichlorphenamide RS in the Standard solution (mg/mL)

Cᵤ = concentration of Dichlorphenamide in the Sample solution (mg/mL)

F = relative response factor (see Table 2)

Acceptance criteria: See Table 2. The reporting threshold is 0.05%.

Table 2

4.3 Chloride and Sulfate 〈221〉, Chloride

Standard solution: 0.28 mL of 0.020 N hydrochloric acid

Sample solution: To 100 mg of Dichlorphenamide add 25 mL of 8 N nitric acid, and warm on a steam bath to dissolve. Cool to room temperature.

Acceptance criteria: 0.20%; the Sample solution shows no more chloride than the Standard solution.

Delete the following:

4.4 Selenium 〈291〉

Sample: A 100-mg specimen mixed with 100 mg of magnesium oxide

Acceptance criteria: NMT 30 ppm

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry at a pressure of NMT 5 mm of mercury at 100° to constant weight.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers. Store at room temperature.

USP Reference Standards 〈11〉

USP Dichlorphenamide RS