Sodium Salicylate

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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C₇H₅NaO₃ 160.10

Benzoic acid, 2-hydroxy-, monosodium salt;

Monosodium salicylate CAS RN®: 54-21-7; UNII: WIQ1H85SYP.

1 DEFINITION

Sodium Salicylate contains NLT 98.0% and NMT 102.0% of sodium salicylate (C₇H₅NaO₃ ), calculated on the anhydrous basis.

2 IDENTIFICATION

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

B. Identification Tests—General, Sodium 〈191〉

Sample solution: 50 mg/mL of Sodium Salicylate in water

Analysis: Proceed as directed for Sodium in the chapter.

Acceptance criteria: Meets the requirements

C. 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

Procedure

Mobile phase: Methanol, tri

uoroacetic acid, and water (40:0.1:60)

Standard solution: 0.04 mg/mL of USP Sodium Salicylate RS in Mobile phase

Sample solution: 0.04 mg/mL of Sodium Salicylate in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 212 nm

Column: 2.1-mm × 5-cm; 1.7-μm packing L1

Column temperature: 30°

Flow rate: 0.2 mL/min

Injection volume: 2 μL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: 0.8–1.8

Relative standard deviation: NMT 0.73%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of sodium salicylate (C₇H₅NaO₃ ) in the portion of Sodium Salicylate 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 Sodium Salicylate RS in the Standard solution (mg/mL)

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

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

4 IMPURITIES

Sulfite or Thiosulfate

Sample solution: 1.0 g of Sodium Salicylate in 20 mL of water

Analysis: Add 1 mL of hydrochloric acid to the Sample solution, and fIlter the liquid.

Acceptance criteria: NMT 0.15 mL of 0.10 N iodine is required to produce a yellow color in the filtrate.

Organic Impurities

Mobile phase: Methanol, trifluoroacetic acid, and water (40:0.1:60)

Standard stock solution: 0.125 mg/mL of USP Sodium Salicylate RS, 0.25 mg/mL of USP Salicylic Acid Related Compound A RS, 0.125 mg/mL of USP Salicylic Acid Related Compound B RS, and 0.05 mg/mL of USP Phenol RS in Mobile phase

Standard solution: 1.25 μg/mL of USP Sodium Salicylate RS, 2.5 μg/mL of USP Salicylic Acid Related Compound A RS, 1.25 μg/mL of USP

Salicylic Acid Related Compound B RS, and 0.5 μg/mL of USP Phenol RS in Mobile phase from Standard stock solution

Sample solution: 2.5 mg/mL of Sodium Salicylate in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 212 nm

Column: 2.1-mm × 5-cm; 1.7-μm packing L1

Column temperature: 30°

Flow rate: 0.2 mL/min

Injection volume: 2 μL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 3.0 between salicylic acid related compound A and phenol; NLT 3.0 between phenol and salicylic acid related compound B

Relative standard deviation: NMT 2% for each peak

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of salicylic acid related compound A, salicylic acid related compound B, or phenol in the portion of Sodium

Salicylate taken:

Result = (r_U /r_S) × (C_S/C_U) × 100

r_U = peak response of salicylic acid related compound A, salicylic acid related compound B, or phenol from the Sample solution

r_S = peak response of salicylic acid related compound A, salicylic acid related compound B, or phenol from the Standard solution

C_S = concentration of USP Salicylic Acid Related Compound A RS, USP Salicylic Acid Related Compound B RS, or USP Phenol RS in the Standard solution (mg/mL)

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

Calculate the percentage of any other individual impurity in the portion of Sodium Salicylate taken:

Result = (r_U /r ) × (C /C_U ) × 100

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

r_S = peak response of salicylic acid related compound B from the Standard solution

C_S = concentration of USP Salicylic Acid Related Compound B RS in the Standard solution (mg/mL)

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

Acceptance criteria: See Table 1.

Table 1

5 SPECIFIC TESTS

Water Determination, Method I〈921〉: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed, light-resistant containers.

Change to read:

USP Reference Standards 〈11〉

USP Phenol RS (ERR 1-Dec-2023)

USP Salicylic Acid Related Compound A RS

4-Hydroxybenzoic acid.

C₇H₆O₃ 138.12

USP Salicylic Acid Related Compound B RS

4-Hydroxyisophthalic acid.

C₈H₆O₅ 182.13

USP Sodium Salicylate RS