... Industry Grade : ItemQuality IndexFood GradeIndustry GradePurity ( As Na2S2O5)98.0% min96.0% minSulfur Dioxide( SO2)65.0% ... and Photo Grade ItemQuality IndexPharmaceutical GradePhoto GradePurity ( As Na2S2O5)98.0% min98.0% minSulfur Dioxide( SO2)65.0% ... We Sell):TCCA,SDIC,sodium hydrosulfite,calcium hypochlorite,hydrofluoric acid,organic matter,sodium sulfide,caustic soda,ammonium bifluoride,potassium ...