Free formaldehyde test

DETERMINATION OF % FREE FORMALDEYDE



Out line of the Method:

The material is treated with Sodium Sulphite soln. and the liberated Sodium Hydroxide is titrate with standard Hydrochloride Acid. The Aldehyde content is then calculated from the amount of Hydrochloric Acid used.

Reagents:

1. Thymolphthalein indicator:

Dissolve 0.1 gr. of Thyophthalein in 100 ml. of 80% rectified spirit.

2. Sodium Hydroxyde soln. of 0.1 N

3. Sodium Sulphite soln.

Dissolve 126 gr. of anhydrous sodium sulphite in 1000 ml. of water.

4. Hydrochloric Acid of 0.1 N.

Procedure:

Weigh 10 to 20 grams of U.F. resin sample in 250 ml. conical flask. Add 10 ml. Butanol and 10 ml. freshly prepared Sodium Sulphite soln. and three drops of Thymol Phthalein indicator. After adding indicator solution becomes blue colour. Titrate with 0.1 N Hydrochloric Acid until the blue colour just disappears.

Calculation:

3.003 X Normality of HCl X B.R.
% HCHO = ----------------------------------------------
Weight of Spl.