Thiamine Mononitrate

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

Thiamine Mononitrate contains NLT 98.0% and NMT 102.0% of thiamine mononitrate, calculated on the dried basis.

2 IDENTIFICATION

A.

Sample solution: 20 mg/mL of Thiamine Mononitrate

Analysis: To 2 mL of the Sample solution add 2 mL of sulfuric acid. Cool, and superimpose 2 mL of ferrous sulfate TS.

Acceptance criteria: A brown ring is produced at the junction of the two liquids.

B.

Sample: 5 mg

Analysis: Dissolve the Sample in a mixture of 1 mL of lead acetate TS and 1 mL of 2.5 N sodium hydroxide. Heat for several min on a steam bath.

Acceptance criteria: After dissolution of the Sample, a yellow color is produced. After heating the solution, the color changes to brown and on standing, a precipitate of lead sulfide separates.

C. A solution of Thiamine Mononitrate yields a white precipitate with mercuric chloride TS, and a red-brown precipitate with iodine TS. It also yields a precipitate with mercuric–potassium iodide TS, and with trinitrophenol TS.

D.

Sample solution: Dissolve 5 mg in 5 mL of 0.5 N sodium hydroxide.

Analysis: To the Sample solution add 0.5 mL of potassium ferricyanide TS and 5 mL of isobutyl alcohol. Shake the mixture vigorously for 2min, and allow the liquid layers to separate.

Acceptance criteria: When illuminated from above by a vertical beam of UV light and viewed at a right angle to this beam, the air–liquid meniscus shows a vivid blue fluorescence, which disappears when the mixture is slightly acidified, but reappears when it is again made alkaline.

3 ASSAY

Procedure

Solution A: 0.005 M sodium 1-octanesulfonate in dilute glacial acetic acid (1 in 100)

Solution B: Methanol and acetonitrile (3:2)

Mobile phase: Solution A and Solution B (60:40)

Internal standard solution: 2.0% (v/v) of methylbenzoate in methanol

Standard solution: Prepare a 1-mg/mL solution of USP Thiamine Hydrochloride RS in Mobile phase. Transfer 20.0 mL of this solution and 5.0mL of Internal standard solution to a 50-mL volumetric flask, and dilute with Mobile phase to volume. The Standard solution contains 400μg/mL of thiamine hydrochloride.

Sample solution: Prepare a 2-mg/mL solution of Thiamine Mononitrate in Mobile phase. Transfer 10.0 mL of this solution and 5.0 mL of Internal standard solution to a 50-mL volumetric flask, and dilute with Mobile phase to volume.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4-mm × 30-cm; packing L1

Flow rate: 1 mL/min. [Note—The flow rate may be adjusted as needed to obtain a retention time of about 12 min for thiamine hydrochloride.]

Injection size: 10 μL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 4.0 between the thiamine and methylbenzoate peaks

Tailing factor: NMT 2.0 for the thiamine peak

Column efficiency: NLT 1500 theoretical plates for the thiamine peak

Relative standard deviation: NMT 2.0% for the ratios of the thiamine peak area to the internal standard peak area

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of thiamine mononitrate in the portion of Thiamine Mononitrate taken:

Result = (R_U/R_S) × (C_S/C_U) × (M_r1/M ) × 100

R_U = internal standard ratio (peak area of thiamine/peak area of the internal standard) from the Sample solution

R_S = internal standard ratio (peak area of thiamine/peak area of the internal standard) from the Standard solution

C_S = concentration of USP Thiamine Hydrochloride RS in the Standard solution (mg/mL)

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

M_r1 = molecular weight of thiamine mononitrate, 327.36

M_r2 = molecular weight of thiamine hydrochloride, 337.27

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

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.2%

Chloride and Sulfate, Chloride〈221〉

Standard: 0.40 mL of 0.020 N hydrochloric acid

Sample: 500 mg of Thiamine Mononitrate

Acceptance criteria: NMT 0.06%

Related Compounds

Solution A, Solution B, and Mobile phase: Proceed as directed in the Assay.

Sample solution: 1.0 mg/mL of Thiamine Mononitrate in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.0-mm × 15-cm; packing L1

Flow rate: 0.75 mL/min

Injection size: 10 μL

Analysis

Sample: Sample solution

Allow the Sample solution to elute for NLT three times the retention time of the main peak.

Calculate the percentage of total secondary peaks in the portion of Thiamine Mononitrate taken:

Result = (r_U/r_T) × 100

r_U = sum of the areas of all the peaks, except that of the thiamine peak

r_T = sum of the areas of all the peaks

Acceptance criteria: NMT 1.0%

5 SPECIFIC TESTS

pH 〈791〉

Sample solution: 20-mg/mL solution

Acceptance criteria: 6.0–7.5

Loss on Drying 〈731〉: Dry 500 mg at 105° for 2 h: it loses NMT 1.0% of its weight.

6 ADDITIONAL REQUIREMENTS

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

USP Reference Standards 〈11〉

USP Thiamine Hydrochloride RS