Selenious Acid Injection

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

1 DEFINITION

Selenious Acid Injection is a sterile solution in Water for Injection of Selenious Acid or of Selenium dissolved in nitric acid. It contains NLT 90.0% and NMT 110.0% of the labeled amount of selenium (Se).

2 IDENTIFICATION

A. The Sample solution, prepared as directed in the Assay, exhibits an absorption maximum at about 196 nm, when tested as directed in the Assay.

3 ASSAY

Procedure

Caution—Selenium is toxic; handle it with care.

Standard stock solution: 1000 µg/mL of selenium, prepared as follows.

Dissolve about 1 g of metallic selenium in a minimum volume of nitric acid.

Evaporate to dryness, add 2 mL of water, and evaporate to dryness.

Repeat the addition of water and the evaporation to dryness three times.

Dissolve the residue in 3 N hydrochloric acid, transfer to a 1000-mL volumetric flask, dilute with 3 N hydrochloric acid to volume, and mix.

Standard solution A: 30 µg/mL of selenium from the Standard stock solution diluted with water

Standard solution B: 40 µg/mL of selenium from the Standard stock solution diluted with water

Standard solution C: 50 µg/mL of selenium from the Standard stock solution diluted with water

Sample solution: 40 µg/mL of selenium from Injection diluted with water

Instrumental conditions

(See Atomic Absorption Spectroscopy 〈852〉.)

Mode: Atomic absorption spectrophotometer

Lamp: Selenium electrodeless discharge

Flame: Air–acetylene

Analytical wavelength: Selenium emission line at 196 nm

Blank: Water

Analysis

Samples: Standard solution A, Standard solution B, Standard solution C, and Sample solution

Plot the absorbances of the Standard solutions versus concentration (µg/mL) of selenium, and draw the straight line best fitting the three plotted points.

From the graph so obtained, determine the concentration, Cₛ, in µg/mL, of selenium in the Sample solution.

Calculate the percentage of the labeled amount of selenium (Se) in the portion of Injection taken:

Result = (Cₛ/Cᵤ) × 100

Cₛ = concentration of selenium in the Sample solution determined from the calibration graph (µg/mL)

Cᵤ = nominal concentration of selenium in the Sample solution (µg/mL)

Acceptance criteria: 90.0%–110.0%

4 SPECIFIC TESTS

pH 〈791〉: 1.8–2.4

Particulate Matter in Injections 〈788〉: Meets the requirements for small-volume injections

Bacterial Endotoxins Test 〈85〉: NMT 3.5 USP Endotoxin Units/µg of selenium

Other Requirements: Meets the requirements in Injections and Implanted Drug Products 〈1〉

5 ADDITIONAL REQUIREMENTS

Packaging and Storage:

Preserve in single-dose or in multiple-dose containers, preferably of Type I or Type II glass.

Labeling:

Label the Injection to indicate that it is to be diluted to the appropriate strength with Sterile Water for Injection or other suitable fluid before administration.