anhydrous sodium sulfite sodium sulfite Application: medicine, papermaking, tannage, leather, printing, ... , avoid contacting sunshine, water and moisture, avoid contacting with strong acid, oxidants or poisonous substances. Exposure to moisture will make it ... insoluble matter , % ≤0.03Free alkali ( as Na2SO3 ) , % ≤0.4 96% Anhydrous Sodium Sulfite