Industry Grade: Purity: 96.0%min Sodium sulphate(SO4): 2.0%max Chloride(as NaCl): 0.5%max Iron: 0.005%max Water insolubles: 0.05%max FoodGrade: Purity: 98.0%min Sodium sulphate(SO4): 1.0%max Chloride(as NaCl): 0.1%max Arsenic: 0.0002%max Heavy metals(as Pb): 0.0005%max Iron: 0.002%max Water insolubles: 0.02%max