Fuchsin Solution, Decolorised

Fuchsin Solution, Decolorised Dissolve 0.1  g of basic fuchsin in 60  ml of water and add 1  g of anhydrous sodium sulphite dissolved in 10  ml of water. Slowly add 2  ml of hydrochloric acid, stirring continuously, and dilute to 100  ml with water. Allow to stand protected from light for at least 12 hours. Shake with sufficient activated charcoal (0.2 to 0.3 g) to remove the colour and then filter immediately. If the solution becomes cloudy, filter before use. If on standing the solution becomes violet, decolorise again by adding activated charcoal.

Complies with the following test.

Sensitivity to formaldehyde To 1.0  ml of the solution add 1.0  ml of water and 0.1  ml of aldehyde-free ethanol (96%). Add 0.2  ml of a solution containing 0.01% w/v of formaldehyde. A pale pink colour is produced within 5 minutes.

Store protected from light.