Protein Precipitation (Salting Out): Saturated (~4.1 M) ammonium sulfate used to fractionate and concentrate proteins from lysates, serum, and culture media.

Antibody Enrichment: Precipitates IgG and other immunoglobulins from serum or ascites for downstream purification.

Ammonium Sulfate Cuts: Stepwise saturation (e.g., 20–80%) to isolate protein fractions based on solubility.

Pre‑Chromatography Cleanup: Removes bulk contaminants and conditions samples prior to ion‑exchange or size‑exclusion chromatography.

Hydrophobic Interaction Chromatography (HIC): Establishes high‑salt binding conditions and starting buffers for HIC workflows.

Protein Crystallization: Acts as a common precipitant in vapor diffusion and batch crystallization screens.

Enzyme Stabilization/Storage: High ionic strength reduces proteolysis and preserves enzyme activity during handling.

Sample Concentration from Cultures: Concentrates secreted proteins/enzymes from microbial supernatants (e.g., Escherichia coli, Bacillus subtilis).

Virus/Bacteriophage Concentration: Precipitates certain viruses and phages from culture fluids for downstream analysis.

Nucleic Acid–Protein Clarification: Selectively precipitates proteins to clarify nucleic acid preparations.