Lactobionic Acid

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

Lactobionic Acid is a mixture in variable proportions of 4-0-B-D-galactopyranosyl-D-gluconic acid and 4-0-B-D-galactopyranosyl-D-glucono-1,5-lactone. It contains NLT 98.0% and NMT 102.0%, on the anhydrous basis.

2 IDENTIFICATION

Change to read:

A. ASPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K. (CN 1-MAY-2020) [NOTE-If the spectra obtained show differences,

dissolve the test substance and USP Lactobionic Acid RS separately in water, dry at 105°, and record new spectra using the residues.]

B. THIN-LAYER CHROMATOGRAPHY (621)

Standard solution: 10 mg/mL of USP Lactobionic Acid RS

Sample solution: 10 mg/mL of Lactobionic Acid

Adsorbent: Chromatographic silica gel mixture with an average particle size of 10-15 µm (TLC plates)

Developing solvent: Methanol, ethyl acetate, ammonium hydroxide, and water (2:1:1:1)

Application volume: 5 µL

Spray reagent: Slowly add 10 mL of sulfuric acid to about 40 mL of water. Mix, and allow to cool. Dilute with water to 100 mL, and mix. Add 2.5 g of ammonium molybdate and 1 g of ceric sulfate, and shake for 15 min to dissolve.

Analysis: Develop the chromatograms until the solvent front has moved about three-fourths the length of the plate, and allow to dry. Spray the plate with Spray reagent, and allow to dry. Repeat two more times, heat at 110° for 15 min, and examine.

Acceptance criteria: The principal spot from the Sample solution is similar in position and color to the principal spot from the Standard solution.

3 ASSAY

PROCEDURE

Sample: 0.350 g of Lactobionic Acid

Analysis: Dissolve the Sample in 50 mL of carbon dioxide-free water, previously heated to 30°. Immediately titrate with 0.1 N sodium hydroxide, and determine the two equivalence points potentiometrically. (See Titrimetry (541).)

Each mL of 0.1 N sodium hydroxide consumed to the first equivalency point is equivalent to 35.83 mg of C12H22O12 (corresponds to the acid form), and each mL of 0.1 N sodium hydroxide consumed between the first and second equivalency points is equivalent to 34.03 mg of C12H20011 (corresponds to the 8-lactone form).

Calculate the content, expressed as a percentage, of the lactobionic acid as the sum of both results.

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

4 SPECIFIC TESTS

WATER DETERMINATION, Method la (921)

Sample solution: 0.50 g in a mixture of methanol and formamide (2:1)

Acceptance criteria: NMT 5.0%

APPEARANCE OF SOLUTION

Sample solution: 120 mg/mL of Lactobionic Acid

Standard stock solution: Pipet 24.0 mL of ferric chloride CS and 6.0 mL of cobaltous chloride CS into a 100-mL volumetric flask. Dilute with 1% (w/v) hydrochloric acid to volume.

Reference solution: Pipet 12.5 mL of the Standard stock solution into a 100-mL volumetric flask. Dilute with 1% (w/v) hydrochloric acid to volume.

Acceptance criteria: The Sample solution is clear and not more intensely colored than the Reference solution.

OPTICAL ROTATION, Specific Rotation (781S).

Sample solution: 10 mg/mL of Lactobionic Acid. Allow to stand for 24 h.

Acceptance criteria: +23.0° to +29.0° (anhydrous substance)

REDUCING SUGARS

Sample solution: Dissolve 5.0 g of Lactobionic Acid in 25 mL of water with the aid of gentle heat, and cool.

Analysis: To the Sample solution add 20 mL of cupric citrate TS and a few glass beads. Heat so that boiling begins after 4 min, and maintain boiling for 3 min. Cool rapidly, and add 100 mL of a 2.4% solution of glacial acetic acid and 20.0 mL of 0.025 M iodine VS. With continuous shaking, add 25 mL of a mixture of 6 mL of hydrochloric acid and 94 mL of water. When the precipitate has dissolved, titrate the excess iodine with 0.05 M sodium thiosulfate VS using 1 mL of starch TS, added toward the end of the titration as an indicator.

Acceptance criteria: NLT 12.8 mL of 0.05 M sodium thiosulfate VS is required, corresponding to NMT 0.2% of reducing sugars, as Glucose.

ARTICLES OF BOTANICAL ORIGIN, Total Ash (561): NMT 0.2%

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers.

USP REFERENCE STANDARDS (11)

USP Lactobionic Acid RS