MF: C4H6O6 Appearance: white crystalline powder ( anhydrate) Assay: 99.5-101.0% Ca: 0.02% max Heavy metal ( as Pb): 0.001% max Arsenic ( As) : 0.0002% max Chloride ( Cl): 0.01% max. Sulfate ( SO4): 0.015% max. Oxalate: 0.035% max Loss on drying: 0.2% max Residue on ignition: 0.1% max