Sodium Propionate

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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C₃H₅NaO₂          96.06

Propanoic acid, sodium salt ^▲_{▲(NF 1-Dec-2022)}:

Sodium propionate ^▲_{▲(NF 1-Dec-2022)}    CAS RN^®: 137-40-6.

Change to read:

1 DEFINITION

Sodium Propionate, dried at 105° for 2 h, contains NLT 98.0% and NMT 102.0% ^▲_{▲(NF 1-Dec-2022)} of sodium propionate (C₃H₅NaO₂).

2 IDENTIFICATION

2.1 A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K

Analysis: Perform test on an undried sample.

Acceptance criteria: Meets the requirements

2.2 B. IDENTIFICATION TESTS-GENERAL (191), Chemical Identification Tests. Sodium

Sample solution: 1 in 20

Acceptance criteria: Meets the requirements

Add the following:

2.3 C. Chromatographic Identity

Analysis: Examine the chromatograms obtained in the Assay.

Acceptance criteria: The retention time of the major peak of the Sample solution corresponds to that of the Standard solution. _{▲(NF 1-Dec-2022)}

3 ASSAY

Change to read:

PROCEDURE

Solution A: 10 mM potassium phosphate, monobasic, with the pH adjusted to 2.5 using phosphoric acid

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: 2% (v/v) phosphoric acid in water

System suitability solution: 2.5 mg/mL of USP Sodium Propionate RS and 0.01 mg/mL of sodium acrylate in Diluent

Standard solution: 2.5 mg/mL of USP Sodium Propionate RS in Diluent

Sample solution: Dry Sodium Propionate at 105° for 2 h. After the sample cools to room temperature in a desicooler or an equivalent device, weigh the sample, and prepare a solution of 2.5 mg/ml. in Diluent.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4.6-mm x 25-cm column; 5-µm packing L1

Column temperature: 45°

Flow rate: 1.0 mL/min

Injection volume: 20 µL

Run time: 35 min

System suitability

Samples: System suitability solution and Standard solution

[NOTE-The approximate relative retention times for related substances are listed in Table 2.]

Suitability requirements

Resolution: NLT 1.5 between the sodium propionate peak and the sodium acrylate peak, System suitability solution

Tailing factor: NMT 2, determined from the sodium propionate peak, Standard solution

Relative standard deviation: NMT 1%, determined from the sodium propionate peak, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of Sodium Propionate in the portion of sample taken:

                   Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak area of sodium propionate from the Sample solution

r_S = peak area of sodium propionate from the Standard solution

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

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

Acceptance criteria: 98.0%-102.0% _{▲(NF 1-Dec-2022)}

Add the following:

4 IMPURITIES

ORGANIC IMPURITIES

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

Sensitivity solution: 0.01 mg/mL of USP Sodium Propionate RS in Diluent

Standard solution: 0.02 mg/mL of USP Sodium Propionate RS in Diluent

Sample solution: 20 mg/mL of Sodium Propionate in Diluent

System suitability

Samples: System suitability solution, Sensitivity solution, and Standard solution.

[NOTE-The approximate relative retention times for related substances are listed in Table 2.]

Table 2

Suitability requirements

Resolution: NLT 1.5 between the sodium propionate peak and the sodium acrylate peak, System suitability solution

Relative standard deviation: NMT 5.0%, determined from the sodium propionate peak, Standard solution

Signal-to-noise ratio: NLT 10, determined from the sodium propionate peak, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

[NOTE-The peak eluting at RRT 0.3 is sodium ion peak. This peak and the peaks eluting before it are exclusive from integration. These peaks are not from organic impurities of sodium propionate.]

Calculate the percentage of each individual impurity in the portion of sample taken:

                   Result = (r_U/r_S) x (C_S/C_U) × (1/F) × 100

r_U = peak area of each individual impurity from the Sample solution

r_S = peak area of sodium propionate from the Standard solution

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

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

F = relative response factor (see Table 3)

Acceptance criteria: See Table 3.

Table 3

5 SPECIFIC TESTS

5.1 WATER DETERMINATION (921), Method /

NMT 1.0%

5.2 ALKALINITY

Sample solution: 2.0 g of Sodium Propionate in 20 mL of water

Analysis: Add phenolphthalein TS to the Sample solution.

Acceptance criteria: If a pink color is produced, it is discharged by 0.60 ml. of 0.10 N sulfuric acid.

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers.

USP REFERENCE STANDARDS (11)

USP Sodium Propionate RS