sodium metabisulfite , high quality and very good price, can accept any test before shipment .

Sodium Metabisulfite

Na2S2O5 96.0%min

Fe 0.005%max

Water Insoluble 0.05%max

Cl 0.003%max

Pb 0.0015max

As 0.0001max

PH 3.2-4.6

Sodium Metabisulfite