1. Iodine dropping method: drop a small amount of Sodium Metabisulfite solution into the water containing starch. If blue or black pigment appears, it means that Sodium Metabisulfite contains iodine ions.

2. Chlorine ion detection method: add Sodium Metabisulfite solution to silver chloride solution. If there is white precipitation, it means that Sodium Metabisulfite contains chlorine ion.

3. Sulfate ion detection method: add Sodium Metabisulfite solution to silver nitrate solution. If there is white precipitation, it means that Sodium Metabisulfite contains sulfate ion.

4. Colorimetry: measure the absorbance of Sodium Metabisulfite solution with ultraviolet visible spectrometer or spectrophotometer, and calculate the concentration of Sodium Metabisulfite according to the relationship between absorbance and concentration.

How to Quickly Detect Sodium Metabisulfite