Assay of Chlorpheniramine Maleate

Aim

To determine the percentage purity of a given sample of Chlorpheniramine malate.

Principle

Chlorpheniramine maleate has chemically known as 3-(4-chlorophenyl) N, N- Dimethyl-3-(2-pyridyl) propylamine hydrogen maleate is an antihistamine H1 receptor antagonist. Mineral acid salts of weak nitrogen bases hydrolyse so extensively in the aqueous or hydro-alcoholic solution that is possible to titrate the liberated acid with a strong mineral base. Titration of the maleate salt of the drug in the water against the sodium hydroxide leads to the formation of water turbidity as the titration proceeds. To prevent this precipitation, alcohol has been used. Since alcohol is basic with respect to water as a solvent, dissolved bases react less strongly alkaline, their salts react more strongly acid, and the endpoints of the titrations are greatly sharpened, here an aqueous solution of Chlorpheniramine maleate was titrated with aqueous NaOH, the turbidity was formed with the appearance of pink as the endpoint.

Reaction

Procedure

Preparation of 0.01M Sodium hydroxide

Weighed accurately about 0.4gm of Sodium hydroxide pellet in a clean 1000ml standard flask then completely dissolved with 100ml distilled water, and makeup to 1000 ml with distilled water.

Standardisation of 0.01M sodium hydroxide

Weighed accurately about 0.5gm of potassium hydrogen phthalate and transferred it into a 1000ml conical flask. Then add 75ml of distilled water to dissolve and titrated with 0.01M sodium hydroxide solution using 0.1ml phenolphthalein as an indicator. The end point is the appearance of permanent pale pink colour.
Each ml of 0.01M Sodium hydroxide= 0.002042g of C8H5KO4

Assay of Chlorpheniramine maleate

Twenty tablets were weighed and grind into a fine powder. An amount of power equivalent to 200mg of chlorpheniramine maleate was weighed
accurately into a 100ml standard flask, 70ml of neutral alcohol was added and shaken for about 20 min. Then, the volume was made up to mark with neutral alcohol, mixed well and filtered using Whatman No 42 filter paper. The first 10 ml portion of the filtrate was discarded. An aliquot of the drug solution containing 2.0-20.0 mg of chlorpheniramine maleate was measured accurately and transferred into a clean 100 ml conical flask and the total volume was brought to 10 ml with a neutral alcohol. Then 2 drops of 0.5% phenolphthalein indicator were added and the solution was titrated with standard 0.01M Sodium hydroxide solution until a permanent pink colour was obtained.
Each ml of 0.01M Sodium hydroxide= 0.002042g of C8H5KO4.

Report

The molarity of 0.01M Sodium hydroxide = ___________________
The percentage purity of given Chlorpheniramine maleate tablet was found to be = ____________________