Taurine

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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C₂H₇NO₃S 125.15

Taurine

Ethanesulfonic acid, 2-amino-;

2-Aminoethane-1-sulfonic acid CAS RN®: 107-35-7; UNII: 1EQV5MLY3D.

1 DEFINITION

Taurine contains NLT 98.0% and NMT 102.0% of taurine (C₂H₇NO₃S), calculated on the dried basis.

2 IDENTIFICATION

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

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

3 ASSAY

Procedure

Solution A: Water adjusted with acetic acid to a pH of 3.0.

Mobile phase: Acetonitrile and Solution A (80:20)

Standard stock solution: Prepare a solution containing 1.0 mg/mL of USP Taurine RS in Mobile phase.

Standard solutions: Using the Standard stock solution prepare three Standard solutions with concentrations of 0.4, 0.5, and 0.6 mg/mL of USP

Taurine RS in Mobile phase.

Sample solution: 0.5 mg/mL of Taurine in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: Evaporative light-scattering detector (ELSD)

Drift tube temperature: 55° or optimize according to the manufacturer's recommendations to achieve optimal signal-to-noise ratio

Nebulizer gas: Nitrogen

Nebulizer gas flow rate: 1.5 L/min or optimize according to the manufacturer's recommendations to achieve optimal signal-to-noise ratio

Column: 3-mm × 10-cm; 2.5-μm packing L104

Column temperature: 25°

Flow rate: 0.4 mL/min

Injection volume: 5 μL

System suitability

Sample: Standard solution at 0.5 mg/mL

Suitability requirements

Column efficiency: NLT 6000 theoretical plates

Tailing factor: NMT 1.5

Relative standard deviation: NMT 3%

Analysis

Samples: Standard solutions and Sample solution

Plot the logarithms of the taurine peak areas against the logarithms of taurine concentrations, in mg/mL, in the three Standard solutions and establish a calibration curve by least-squares regression. The correlation coefficient for the regression line is NLT 0.99. Inject the

Sample solution three times and obtain the average value of taurine peak areas. Using the logarithm of the average taurine peak area from the Sample solution, calculate the logarithm of taurine concentration from the calibration curve and calculate the concentration, C, in mg/mL, of taurine in the Sample solution by taking the antilog of the result.

Calculate the percentage of taurine (C₂H₇NO₃S) in the portion of Taurine taken:

Result = (C/C_U ) × 100

C = concentration of Taurine in the Sample solution (mg/mL), determined from the calibration curve

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

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

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.3%

Chloride and Sulfate 〈221〉, Chloride

Standard: 0.50 mL of 0.020 N hydrochloric acid

Sample: 0.7 g of Taurine

Acceptance criteria: NMT 0.05%

Chloride and Sulfate 〈221〉, Sulfate

Standard: 0.25 mL of 0.020 N sulfuric acid

Sample: 0.8 g of Taurine

Acceptance criteria: NMT 0.03%

Change to read:

Iron 〈241〉, Procedures, Procedure 1 (CN 1-Jun-2023) : NMT 30 ppm

Related Compounds

Sample solution: 10 mg/mL of Taurine in water

Standard solution: 0.05 mg/mL of USP Taurine RS in water, an equivalent concentration of about 0.5% of the Sample solution

Chromatographic system

(See Chromatography 〈621〉, General Procedures, Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 5 μL

Developing solvent system: Butyl alcohol, glacial acetic acid, and water (3:1:1)

Spray reagent: 2 mg/mL of ninhydrin in a mixture of butyl alcohol and 2 N acetic acid (95:5)

Analysis: Dry the plate at 80° for 30 min. Spray the plate with Spray reagent, and heat at 80° for about 10 min. Examine the plate under white light. [Note—The R value for the taurine spots should be about 0.2.]

Acceptance criteria: No secondary spot of the Sample solution is larger or more intense than the principal spot of the Standard solution.

Individual impurities: NMT 0.5%

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry at 105° for 3 h.

Acceptance criteria: NMT 0.3%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Taurine RS