Sodium Hypochlorite Solution

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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NaClO 74.44

Hypochlorous acid, sodium salt;

Sodium hypochlorite CAS RN®: 7681-52-9; UNII: DY38VHM5OD.

1 DEFINITION

Sodium Hypochlorite Solution contains NLT 4.0% and NMT 6.0%, by weight, of sodium hypochlorite (NaClO).

[Caution—This solution is not suitable for application to wounds.]

2 IDENTIFICATION

A. Sample: Sodium Hypochlorite Solution

Acceptance criteria: The Sample at first colors red litmus blue and then bleaches it.

B. Sample: Sodium Hypochlorite Solution

Acceptance criteria: The Sample imparts an intense yellow color to a nonluminous flame.

3 ASSAY

Procedure

Sample solution: 3 g of Sodium Hypochlorite Solution

Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.1 N sodium thiosulfate VS

Endpoint detection: Visual

Analysis: Dilute the Sample solution with 50 mL of water, and add 2 g of potassium iodide and 10 mL of 6 N acetic acid. Titrate the liberated iodine with Titrant, adding 3 mL of starch TS as the endpoint is approached. Perform a blank determination, and make any necessary correction.

Calculate the percentage of sodium hypochlorite (NaClO) in the portion of Sodium Hypochlorite Solution taken:

Result = [(V − B) × N × (F/W)] × 100

V = sample Titrant volume (mL)

B = blank Titrant volume (mL)

N = normality of the Titrant (mEq/mL)

F = 37.22 mg/mEq

W = sample weight (mg)

Acceptance criteria: 4.0%–6.0%

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers, at a temperature not exceeding 25°.