Assay: 99%min. Chloride: 0.005%max. Sulfate: 0.01%max. Phosphate: 0.001%max. Mg: 0.001%max. Iron: 0.001%max. Al: 0.002%max. Ca: 0.05%max. Heavy Metals: 0.002%max. Water Insolubility: 0.01%max