Trolamine Salicylate

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

C₁₃H₂₁NO₆             287.31

Triethanolamine salicylate CAS RN^®: 2174-16-5; UNII: H804040BHD.

1 DEFINITION

Trolamine Salicylate is a compounded mixture of Trolamine and Salicylic Acid in propylene glycol. It contains NLT 95.0% and NMT 105.0% of the labeled amount of trolamine salicylate (C₁₃H₂₁NO₆).

2 IDENTIFICATION

Change to read:

A. ^▲SPECTROSCOPIC IDENTIFICATION TESTS (197), Ultraviolet-Visible Spectroscopy: 1974 _{▲(CN 1-May-2020)}

Sample solution: 1 mg/mL. The Sample solution and the Standard solution contain the equivalent of 1 mg/mL of salicylic acid in Medium.

Medium: Methanol

Cell: 0.1 cm

Acceptance criteria: Absorptivities do not differ by more than 1.0%.

3 ASSAY

PROCEDURE

Mobile phase: Acetonitrile and water (3:7)

Standard solution: 48 µg/mL of USP Salicylic Acid RS in methanol

Sample solution: Transfer an amount equivalent to 300 mg of salicylic acid from a portion of Trolamine Salicylate, into a 250-ml volumetric flask, and dilute with methanol to volume. Transfer 2 mL of this solution to a 50-mL volumetric flask, and dilute with methanol to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 308 nm

Column: 4.0-mm x 12.5-cm ; packing L7

Flow rate: 1 mL/min

Column temperature: 30°

Injection volume: 10 µL

System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 8000 theoretical plates

Tailing factor: NMT 1.5

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of trolamine salicylate (C₁₃H₂₁NO₆) in the portion of Trolamine Salicylate taken:

                         Result = (r_U/r_S) x 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

Acceptance criteria: 95.0%-105.0%

4 IMPURITIES

4.1 LIMIT OF FREE SALICYLIC ACID

Standard solution 1: 0.2 mg/mL of USP Salicylic Acid RS in xylene

Standard solution 2: 0.1 mg/mL of USP Salicylic Acid RS from Standard solution 1 in xylene

Sample solution: 0.96 mg/mL of Trolamine Salicylate in xylene

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: Toluene, acetone, and glacial acetic acid (17:8:0.2)

Analysis: Proceed as directed in the chapter. Develop in a chamber previously equilibrated with Developing solvent system. Examine the plate under long-wavelength UV light.

Acceptance criteria: NMT 0.02%; any secondary spot of the Sample solution is not greater in size or intensity than the spot of Standard solution 1.

4.2 OTHER ORGANIC IMPURITIES

Mobile phase, Standard solution, Chromatographic system, and System suitability: Proceed as directed in the Assay.

Sample solution: Use the Sample solution from the Assay.

Analysis

Sample: Sample solution

Calculate the percentage of each impurity in the portion of Trolamine Salicylate taken:

                         Result = (r_U/r_T) x 100

r_U = peak response for each impurity

r_T = sum of all the peak responses

Acceptance criteria: NMT 1.0% of any individual impurity and NMT 2.0% of total impurities are found.

5 SPECIFIC TESTS

SPECIFIC GRAVITY (841): 1.190-1.220

REFRACTIVE INDEX (831): 1.505-1.535 at 20°

pH (791)

Solution: 50 mg/mL

Acceptance criteria: 6.5-7.5

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers in a cool place.

USP REFERENCE STANDARDS (11)

USP Salicylic Acid RS