CAS number 7783-18-8 EC number 231-982-0 Hill Formula H₈N₂O₃S₂ Chemical formula (NH₄)₂S₂O₃ Molar Mass 148.19 g/mol HS Code 2832 30 00 Specifications Assay (iodometric) ≥ 98.0 % pH-value (5 %; water) 5.0 – 7.0 Chloride (Cl) ≤ 0.05 % Sulfate and sulphite (as SO₄) ≤ 1 % Sulphide (S) ≤ 0.001 % Heavy metals (as Pb) ≤ 0.002 % Ca (Calcium) ≤ 0.005 % Fe (Iron) ≤ 0.002 % Na (Sodium) ≤ 2 %