Butamben

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

Butamben contains NLT 98.0% and NMT 102.0% of butamben (C₁₁H₁₅NO₂), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197A or 197K (CN 1-May-2020)

B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Solution A: Add 1.0 mL of 98 percent formic acid to 1 L of water, and mix well.

Solution B: Add 1.0 mL of 98 percent formic acid to 1 L of acetonitrile, and mix well.

Mobile phase: See Table 1.

Table 1

Standard solution: 0.2 mg/mL of USP Butamben RS prepared as follows. Transfer a suitable quantity of USP Butamben RS to an appropriate volumetric flask. Add 10% of the total flask volume of acetonitrile to dissolve, then dilute with water to volume.

Sample solution: 0.2 mg/mL of Butamben prepared as follows. Transfer a suitable quantity of Butamben to an appropriate volumetric flask. Add 10% of the total flask volume of acetonitrile to dissolve, then dilute with water to volume.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 285 nm

Column: 2.1-mm × 10-cm; 5-µm packing L1

Flow rate: 0.4 mL/min

Injection volume: 1 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 butamben (C₁₁H₁₅NO₂) in the portion of Butamben 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 Butamben RS in the Standard solution (mg/mL)

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

Acceptance criteria: 98.0%–102.0% on the dried basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281): NMT 0.2%

4.2 ORGANIC IMPURITIES

Solution A, Solution B, Mobile phase, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Diluent: Acetonitrile and water (10:90)

Standard stock solution: 0.1 mg/mL each of USP Butamben RS and USP Aminobenzoic Acid RS prepared as follows. Transfer a suitable quantity of each Reference Standard to an appropriate volumetric flask. Add 10% of the total flask volume of acetonitrile to dissolve, then dilute with water to volume.

Standard solution: 0.2 µg/mL each of USP Butamben RS and USP Aminobenzoic Acid RS from the Standard stock solution in Diluent

[Note—The use of blank injections of Diluent may be suitable to reduce carryover between injections of the Sample solution and the Standard solution, if observed.]

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 10 between the aminobenzoic acid and butamben peaks

Relative standard deviation: NMT 5% for each peak corresponding to aminobenzoic acid and butamben

Analysis

Samples: Sample solution and Standard solution

Calculate the percentage of aminobenzoic acid in the portion of Butamben taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of aminobenzoic acid from the Sample solution

r_S = peak response of aminobenzoic acid from the Standard solution

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

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

Calculate the percentage of any individual unspecified impurity in the portion of Butamben taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of any other individual impurity from the Sample solution

r_S = peak response of butamben from the Standard solution

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

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

Acceptance criteria: See Table 2. Disregard any impurity peak less than 0.05%.

Table 2

5 SPECIFIC TESTS

LOSS ON DRYING (731)

Analysis: Dry over phosphorus pentoxide for 3 h.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers.

USP REFERENCE STANDARDS (11)

USP Aminobenzoic Acid RS

Benzoic acid, 4-amino.

C₇H₇NO₂ 137.14

USP Butamben RS