Potassium Chloride

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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KCl 74.55

Potassium chloride CAS RN®: 7447-40-7.

1 DEFINITION

Potassium Chloride contains NLT 99.0% and NMT 100.5% of KCl, calculated on the dried basis.

2 IDENTIFICATION

A. Identification Tests - General, Potassium〈191〉

Sample solution: 50 mg/mL

Acceptance criteria: Meets the requirements

B. Identification Tests - General, Chloride〈191〉

Sample solution: 50 mg/mL

Acceptance criteria: Meets the requirements

3 ASSAY

Procedure

Sample: 200 mg

Analysis: Dissolve the Sample in 10 mL of water. Add 10 mL of glacial acetic acid, 75 mL of methanol, and 3 drops of eosin Y TS. Titrate, with shaking, with 0.1 N silver nitrate VS to a pink endpoint. Each mL of 0.1 N silver nitrate is equivalent to 7.455 mg of KCl.

Acceptance criteria: 99.0%–100.5% on the dried basis

4 IMPURITIES

Change to read:

Aluminum 〈206〉, Procedure 1 (CN 1-Jun-2023) (where it is labeled as intended for use in hemodialysis): Proceed as directed, using 2.0g of Potassium Chloride to prepare the Test preparation.

Acceptance criteria: NMT 1 ppm

4.1 Sodium

Sample solution: 50 mg/mL

Acceptance criteria: Sample solution tested on a platinum wire does not impart a pronounced yellow color to a nonluminous flame.

4.2 Iodide

Standard stock solution: 1.64 mg/mL of potassium iodide in water

Standard solution: Dilute 1.0 mL of Standard stock solution with water to 25 mL. Dilute 2.0 mL of this solution with water to 8 mL. Add 1 mL each of chloroform and diluted hydrochloric acid, then add 2 drops of a chloramine T solution (0.1 in 100), and shake gently.

Sample solution: Dissolve 2 g of Potassium Chloride in 8 mL of water. Add 1 mL each of chloroform and diluted hydrochloric acid, then add 2 drops of a chloramine T solution (0.1 in 100), and shake gently.

Acceptance criteria: The violet color of the chloroform layer is not darker than that of a concomitantly prepared Standard solution (NMT 0.005%).

4.3 Bromide

Standard stock solution: 1.28 mg/mL of sodium bromide in water

Standard solution: Dilute 2.0 mL of Standard stock solution with water to 8 mL. Add 1 mL each of chloroform and diluted hydrochloric acid, then add 5 drops of a chloramine T solution (1 in 100), and shake gently.

Sample solution: Dissolve 2 g of Potassium Chloride in 8 mL of water. Add 1 mL each of chloroform and diluted hydrochloric acid, then add 5 drops of a chloramine T solution (1 in 100), and shake gently.

Acceptance criteria: The brown color of the chloroform layer is not darker than that of a concomitantly prepared Standard solution (NMT 0.1%).

4.4 Calcium and Magnesium

Sample solution: 10 mg/mL in water

Analysis: To 20 mL of Sample solution add 2 mL each of 6 N ammonium hydroxide, ammonium oxalate TS, and dibasic sodium phosphate TS.

Acceptance criteria: No turbidity is produced within 5 min.

5 SPECIFIC TESTS

Acidity or Alkalinity: To a solution of 5.0 g in 50 mL of carbon dioxide-free water add 3 drops of phenolphthalein TS: no pink color is produced. Then add 0.30 mL of 0.020 N sodium hydroxide: a pink color is produced.

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

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

Labeling: Where Potassium Chloride is intended for use in hemodialysis, it is so labeled.