WATER SOLUBLE MATTER

This method covers the determination of water soluble matter in pigments and extenders.

APPARATUS AND REAGENTS :

1. Beaker 250 ml.
2. Gas burner.
3. Glass rod.
4. Whatman filter paper No.5.
5. Evaporating dish 250 ml.
6. Desiccator.
7. Distilled water.

PROCEDURE :

1. Weigh accurately to the nearest mgs. 15 to 20 gms of the test sample.

2. Transfer the weighed sample into a clean 250 ml beaker.

3. Add 100 ml of distilled water.

4. Mix the contents thoroughly with the help of a glass rod. (Practicularly for organic pigments before adding water it is better to wet the pigment with few drops of alcohol or any suitable wetting agent).

5. Gently boil the beaker and its contents and filter using whatman filter paper No.5.

6. Collect the filterate in a clean dry previously weighed evaporating dish.

7. Evaporate the water carefully and when dry cool in desiccator and reweigh the evaporating dish.

8. Test to be done in duplicate.

CALCULATION :

A = Wt. of empty evaporating dish.
B = Wt. or the test sample.
C = Wt. of evaporating dish with the water solubles.
C-A = Wt. of the water soluble matter.