reducer of coloring matter and chemical industries,printing and dyeing industries,medicine,pear making industries Grade 1Grade 2Grade 3Grade 4Sodium Sulfite, Content (Na2SO3) %>=97.096.093.096.0Ferro(Fe) %<=0.0030.0050.010.005Water-Insoluble Material %<=0.020.030.050.03Free (Na2CO3)%<=0.10.400.600.60Heavy Metal (Pb)%<= 0.002Arsenic (As)%<= 0.0002AppearanceWhite Crystal Powder Application:this ...