Potassium chloride (non-injectable)

Potassium chloride for parenteral use

Molecular formula. KCl

Relative molecular mass. 74.55

Chemical name. Potassium chloride; CAS Reg. No. 7447-40-7.

Description. Colourless crystals or a white, crystalline powder; odourless.

Solubility. Soluble in 3 parts of water; practically insoluble in ethanol (~750 g/l) TS.

Category. Ionic equilibration agent.

Storage. Potassium chloride should be kept in a well-closed container.

Labelling. The designation Potassium chloride for parenteral use indicates that the substance complies with the additional requirement given at the end of this monograph and may be used for parenteral administration or for other sterile applications.

Requirements

Definition. Potassium chloride contains not less than 99.0% and not more than 100.5% of KCl, calculated with reference to the dried substance.

Identity tests

A. To a 0.05 g/mL solution add 2 mL of sodium hydroxide (~80 g/l) TS; it yields the reaction described under 2.1 General identification tests as characteristic of potassium.

B. A 0.05 g/mL solution yields reaction A described under 2.1 General identification tests as characteristic of chlorides.

Heavy metals. Use 1.0 g for the preparation of the test solution as described under 2.2.3 Limit test for heavy metals, Procedure 1; determine the heavy metals content according to Method A; not more than 10 μg/g.

Iron. Use 1.0 g; the solution complies with the 2.2.4 Limit test for iron; not more than 40 μg/g.

Calcium and magnesium. To 20 mL of a 10 mg/mL solution add 2 mL of ammonia (~100 g/l) TS, 2 mL of ammonium oxalate (25 g/l) TS and 2 mL of disodium hydrogen phosphate (40 g/l) TS; no turbidity is produced within 5 minutes.

Barium. Dissolve 0.5 g in 10 mL of carbon-dioxide-free and ammonia-free water R and add 1 mL of sulfuric acid (~100 g/l) TS; no turbidity is produced within 1 minute.

Arsenic. Use a solution of 3.3 g in 35 mL of water and proceed as described under 2.2.5 Limit test for arsenic; the arsenic content is not more than 3 μg/g.

Bromides. Dissolve 0.08 g in 10 mL of water, add 0.25 mL of sulfuric acid (0.5 mol/L) VS and 2 drops of tosylchloramide sodium (15 g/L) TS and mix; allow to stand for 2 minutes and extract with 5 mL of chloroform R. Prepare a reference solution by treating a mixture of 1.0 mL of potassium bromide (0.119 g/L) TS and 9 mL of water in a similar manner. Transfer the extracts to matched 10 mL stoppered test-tubes of transparent glass, add to each tube 3 mL of fuchsin TS, shake vigorously and allow to separate. The colour of the chloroform layer of the test solution when viewed transversely against a white background is not more intense than that produced in the reference solution when compared as described under 1.11.1 Colour of liquids.

Iodides. Moisten 5 g by adding, drop by drop, a recently prepared mixture composed of 25 mL of starch TS, 2 mL of sulfuric acid (0.5 mol/l) VS, 2 mL of sodium nitrite (10 g/l) TS, and 25 mL of water. Examine the mixture in daylight; no particles show any trace of blue colour within 5 minutes.

Sulfates. Dissolve 1.7 g in 20 mL of water and proceed as described under 2.2.2 Limit test for sulfates; the sulfate content is not more than 0.3 mg/g.

Clarity and colour of solution. A solution of 1.0 g in 10 mL of water is clear and colourless.

Loss on drying. Dry to constant weight at 130°C; it loses not more than 10 mg/g.

Acidity or alkalinity. Dissolve 5.0 g in 50 mL of carbon-dioxide-free water R, and add 0.1 mL of bromothymol blue/ethanol TS; not more than 0.2 mL of sodium hydroxide (0.02 mol/l) VS or 0.2 mL of hydrochloric acid (0.02 mol/l) VS is required to obtain the midpoint of the indicator (green).

Assay. Dissolve about 1.0 g, accurately weighed, in sufficient water to produce 100 mL. To 10.0 mL add 50 mL of water, 5 mL of nitric acid (~130 g/l) TS, 25.0 mL of silver nitrate (0.1 mol/l) VS, and 2 mL of dibutyl phthalate R, shake the flask and titrate with ammonium thiocyanate (0.1 mol/l) VS using 2.5 mL of ferric ammonium sulfate (45 g/l) TS as indicator. Each mL of silver nitrate (0.1 mol/l) VS is equivalent to 7.455 mg of KCl.

Additional Requirement for Potassium Chloride for Parenteral Use

Complies with the monograph for "Parenteral preparations".

Bacterial endotoxins. Carry out the test as described under 3.4 Test for bacterial endotoxins; contains not more than 8.8IU of endotoxin RS per milliequivalence.

Sodium. Determine by atomic absorption spectrophotometry as described under 1.8 Atomic spectrometry: emission and absorption, at a wavelength of 589 nm; use a standard solution of sodium chloride R, previously dried to constant weight, dissolved in 1000 mL of water to contain 508.4 mg of NaCl (0.2 mg of Na per mL); the sodium content is not more than 1.0 mg/g.

Additional requirement for Potassium chloride for sterile use

Complies with 3.2 Test for sterility.