Biomolecule Purification is used extensively in biotechnology fields for research and the development of pharmaceuticals. The purification process helps scientists isolate proteins and DNA from complex mixtures.

The purification process begins with breaking down cells to study their base structures. This process, called Cell Lysis, may use several different methods. The desired result of Cell Lysis is to break down cell walls and separate the cell's molecules.

Once the cell breaks down into a soluble supernatant, the larger particles are filtered out using centrifugal filter tubes in a centrifuge. These molecules are extremely tiny. Depending on the biomolecules needed for testing, the scientist may choose from microfiltration, ultrafiltration, or nanofiltration processes. Typical filtration media, with pores as small as 0.2 µm to 0.05 µm, is necessary.

Often, the filtered proteins require additional processing before use. A salt, usually ammonium sulfate, is gradually added to the protein solution. This process is called "salting-in". The ammonium sulfate increases the ionic strength of the solution. As the ionic strength increases, the protein solubility decreases. Salt ions compete with the protein molecules to join with water molecules. In this solution, the protein molecules are concentrated and precipitate out. Further centrifugal filtration is required to recover the protein molecules.

Additional purification, using chromatography, separates molecules based on size or ionic charge. Size exclusion, ion exchange, affinity, and hydrophobic interaction chromatography produce differing results. For high-resolution results some bioengineers use High-Performance Liquid Chromatography (HPLC).

Biomolecule purification is used when developing therapeutic drugs, vaccines, research, diagnostic tests, and industrial processes for food production, textile manufacturing, and biofuel production.