Take some turmeric powder in a transparent glass and add a few drops of water and concentrated hydrochloric acid to it. Next, shake it vigorously. A pink colour to the mixture indicates the presence of metanil yellow. If the mixture releases small bubbles, it indicates the presence of chalk powder. (Caution- this test should not be carried out at home as it involves the use of concentrated hydrochloric acid)
To detect the presence of lead chromate, mix a teaspoon of turmeric powder with water. If adulterated, it will immediately leak streaks of water-soluble colour.
Another easy way to check adulteration is to add a teaspoon of turmeric to a glass of warm water. Do not stir it and leave it still for a while. Check after about 20 minutes. If the powder settles down at the bottom of the glass with clear water above, the turmeric is pure. Cloudy water indicates possible adulteration.