Polymerase Chain Reaction (PCR) is a process where millions of copies of DNA are amplified from a single copy, or low copy number template. This reaction is fundamental to almost all applications requiring high copy number of starting material and is used in all laboratories working with DNA and RNA. Because of the high copy number that is generated during PCR, it is absolutely essential to prevent contamination of the PCR reaction.

In addition to good laboratory practice, the ideal PCR laboratory should consist of three areas, each isolated from the other. Reagents should be prepared in the reagent preparation area and transferred to the sample preparation area, through a pass box, or inside closed containers. After preparation of the final reaction mix, the tubes should be transferred to the amplification area, again through a pass box or in a closed container. The PCR amplification and results analysis takes place in this area. To guarantee contaminant-free samples, it is essential to work in an environment where the air quality is controlled, such as a PCR clean bench, vertical laminar flow or biological safety cabinet.