Sodium disulfite / sodium metabisulfite 4% is used in medical diagnostics, histology and scientific laboratories. A significant use is to be part of the staining kit for Hepatitis B Antigen Victoria Blue staining.

The solution consists of distilled water and sodium disulfite. Sodium disulfite (CAS No.: 7681-57-4) is an inorganic salt that is highly soluble in water and serves as a reducing agent. It reacts in solution to reduce or stabilize dyes, enabling their attachment to specific cells or tissue structures.

The action of the solution results from the chemical interaction between the sodium disulfite and the components of the tissue being dyed. Specific patterns and structures can be highlighted by the staining.