Colorless crystalline powder Titration analysis cadmium the following is details information about our sodium sulfite:1. Appearance: Sodium metabisulphite grade one is white crystal powder.2.The Spec as follow:Main content(Na2S2O5), % >= 95% Content of iron(Fe), % <= 0.005% turbid Content of heavy metal(in pb), % <= 0.001%Content of arsenic(As) % <= 0.0002%