How can one check if spices are pure as per FSSAI?

After dye used to colour clothes was found in spices at a Ghaziabad mill, an FSSAI official said pure turmeric's yellow will fade when mixed with water. To check if chilli powder is pure, add it to water. If residue feels gritty, smooth or brighter, then it's adulterated. After soaking adulterated coriander powder in water, dung or sawdust will float.