Aminobenzoate Potassium

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

Aminobenzoate Potassium contains NLT 98.0% and NMT 102.0% of aminobenzoate potassium (C₇H₆KNO₂), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 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.

C.

Sample solution: 10 mg/mL of Aminobenzoate Potassium in water

Acceptance criteria: The Sample solution imparts a violet color to a nonluminous flame. Since the presence of small quantities of sodium masks the color, screen out the yellow color produced by sodium by viewing through a blue filter that blocks emission at 589 nm (sodium) but is transparent to emission at 404 nm (potassium). [Note—Traditionally, cobalt glass has been used, but other suitable filters are commercially available.]

3 ASSAY

3.1 Procedure

Solution A: 1.5% acetic acid, prepared by mixing 690 mL of water with 10 mL of glacial acetic acid and passing through a suitable filter of 0.45-μm pore size

Mobile phase: Methanol and Solution A (15:85)

Standard solution: 0.1 mg/mL of USP Aminobenzoate Potassium RS in Mobile phase. Sonicate to dissolve.

Sample solution: 0.1 mg/mL of Aminobenzoate Potassium in Mobile phase. Sonicate to dissolve.

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 280 nm

Column: 3.0-mm × 15-cm; 3.5-μm packing L11

Flow rate: 0.35 mL/min

Injection volume: 5 μL

3.3 System suitability

Sample: Standard solution

3.4 Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 0.73%

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of aminobenzoate potassium (C₇H₆KNO₂) in the portion of Aminobenzoate Potassium 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 Aminobenzoate Potassium RS in the Standard solution (mg/mL)

C_u = concentration of Aminobenzoate Potassium in the Sample solution (mg/mL)

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

4 IMPURITIES

Delete the following:

Heavy Metals 〈231〉, Method II: NMT 0.002%  (Official 1-Jan-2018)

Change to read:

4.1 Limit of Aniline and p-Toluidine

Diluent: Methylene chloride

Standard stock solution: 0.1 mg/mL each of USP Aniline RS and USP p-Toluidine RS in Diluent

Standard solution: 1 μg/mL each of USP Aniline RS and USP p-Toluidine RS in Diluent from Standard stock solution

Sample solution: 100 mg/mL of Aminobenzoate Potassium in Diluent prepared as follows. Add an appropriate quantity of Aminobenzoate

Potassium to a suitable volumetric flask and dilute with Diluent to volume. Agitate for 10 min on a shaker and centrifuge at 3000 rpm for 5min. Use the supernatant.

4.1.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detectors

Flame ionization: 300°

Hydrogen: 40 mL/min

Air: 400 mL/min

Column: 30-m × 0.32-mm fused silica capillary; coated with 0.5-μm film of phase G27

Temperatures

Injection port: 280°

Detector: 300°

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 1.0 mL/min

Injection volume: 2 μL

Injection type: Split ratio, 1:10

4.1.2 System suitability

Sample: Standard solution

[Note-The relative retention times of aniline and p-toluidine are 0.8 and 1.0, (ERR 1-Sep-2018) respectively.]

4.1.3 Suitability requirements

Resolution: NLT 7.0 between aniline and p-toluidine

Tailing factor: NMT 1.5 for aniline and p-toluidine

Relative standard deviation: NMT 6.0% for aniline and p-toluidine

4.1.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of p-toluidine or aniline in the portion of Aminobenzoate Potassium taken:

Result = (r_u/r_s) × (C_s/C_u) × 100

r_u = peak response of p-toluidine or aniline from the Sample solution

r_s = peak response of p-toluidine or aniline from the Standard solution

C_s = concentration of the corresponding USP Reference Standard in the Standard solution (mg/mL)

C_u = concentration of Aminobenzoate Potassium in the Sample solution (mg/mL)

4.1.5 Acceptance criteria

Aniline: NMT 10 ppm

p-Toluidine: NMT 20 ppm

4.2 Organic Impurities

Solution A: 1.5% acetic acid, prepared by mixing 690 mL of water with 10 mL of glacial acetic acid

Solution B: Methanol

Mobile phase: See Table 2.

Table 2

Diluent: Methanol and water (85:15)

System suitability solution: 1 mg/mL of USP Aminobenzoate Potassium RS, 0.01 mg/mL of USP 4-Nitrobenzoic Acid RS, and 0.01 mg/mL of USP Benzocaine RS in Diluent prepared as follows. Transfer 1 mL each of 0.1 mg/mL of USP 4-Nitrobenzoic Acid RS in methanol and 0.1 mg/mL of USP Benzocaine RS in Diluent to a 10-mL volumetric flask containing the appropriate amount of USP Aminobenzoate Potassium RS, and dilute with Diluent to volume.

Standard solution: 1 μg/mL each of USP Aminobenzoate Potassium RS, USP 4-Nitrobenzoic Acid RS, and USP Benzocaine RS in Diluent

Sample solution: 1 mg/mL of Aminobenzoate Potassium in Diluent

4.2.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 280 nm

Column: 3.0-mm × 15-cm; 3.5-μm packing L11

Flow rate: 0.4 mL/min

Injection volume: 5 μL

4.2.2 System suitability

Samples: System suitability solution and Standard solution

4.2.3 Suitability requirements

Resolution: NLT 1.5 between benzocaine and 4-nitrobenzoic acid, System suitability solution

Relative standard deviation: NMT 3% for the aminobenzoate potassium, 4-nitrobenzoic acid, and benzocaine peaks, Standard solution

4.2.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of 4-nitrobenzoic acid or benzocaine in the portion of Aminobenzoate Potassium taken:

Result = (r_u/r_s) × (C_s/C_u) × 100

r_u = peak response of 4-nitrobenzoic acid or benzocaine from the Sample solution

r_s = peak response of 4-nitrobenzoic acid or benzocaine from the Standard solution

C_s = concentration of USP 4-Nitrobenzoic Acid RS or USP Benzocaine RS in the Standard solution (mg/mL)

C_u = concentration of Aminobenzoate Potassium in the Sample solution (mg/mL)

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

Result = (r_u/r_s) × (C_s/C_u) × 100

r_u = peak response of any unspecified impurity from the Sample solution

r_s = peak response of aminobenzoate from the Standard solution

C_s = concentration of USP Aminobenzoate Potassium RS in the Standard solution (mg/mL)

C_u = concentration of Aminobenzoate Potassium in the Sample solution (mg/mL)

Acceptance criteria: See Table 3.

Table 3

5 SPECIFIC TESTS

pH 〈791〉

Sample solution: 50 mg/mL of Aminobenzoate Potassium in water

Acceptance criteria: 8.0–9.0

Loss on Drying 〈731〉

Analysis: Dry at 105° for 2 h.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Aminobenzoate Potassium RS

USP Aniline RS

Aniline.

C₆H₇N 93.13

USP Benzocaine RS

USP 4-Nitrobenzoic Acid RS

4-Nitrobenzoic acid.

C₇ H₅NO₄ 167.12

USP p-Toluidine RS

4-Methylaniline.

C₇H₉N 107.15