... Appearance : white or light yellow crystalline powder4,Main content :96.5%min 5,Competitive price, Pass ISO 6,Annuual production:20,000mt Quality ... : GB1893-1998Item Company standardAssay ( as Na2S2O5 ) % ≥96.5Fe % ≤0.003ClarityclearHeavy metal (Pb)% ≤0.0005As % ≤0.0001Usage1, As the material of medicine2 ... (0086-13762006068) in Yueyang Sanxiang Chemical Co.,Ltd. 96.5% min Sodium metabisulfite (SM158)