DNA sampling allows criminal investigators to compare recovered DNA evidence to that of a suspect's profiles. Scientists can amplify genetic material using Polymerase Chain Reaction (PCR), even when minute amounts of DNA evidence are collected from a crime scene. PCR is, however, extremely susceptible to contamination as it is unable to separate DNA from different sources. This means it is essential to protect evidence from contamination at every step in the chain of custody.
During the evidence collection processing or handling, the use of personal protective equipment (PPE) reduces the possibility of cross-contamination with the examiner's genetic material or fingerprints. Blood, DNA and other types of forensic evidence are then often specially dried before storage to prevent the degradation of evidence.
Once in the forensic laboratory, cross-contamination prevention comes down to the right laboratory equipment. When analyzing DNA evidence, thermocyclers or PCR machines should be operated in a PCR hood in accordance with CDC recommendations1. PCR laminar flow hoods or workstations help prevent cross-contamination that can adversely affect samples. While they protect the sample from contaminations, they are intended for use with non-hazardous applications where biological or biohazard byproducts are not generated, and user protection is not required.
Air Science® PCR Laminar Flow Cabinet
Air Science Purair PCR workstation enclosures provide a safe, energy-efficient, contamination-free environment during PCR amplification. The Purair PCR workstation is designed to provide flexible access to the thermocycler while protecting against cross-contamination. The unvented unit uses Air Science Multiplex™ HEPA filtration technology which consists of a pre-filter and HEPA filter. Air Science Purair PCR workstations are designed for versatility. They can be installed directly on the desktop or the optional mobile cart and are available in three models with various options.
1 The CDC recommends conducting work in an unventilated, still air PCR hood (biocontainment cabinet) to minimize cross-contamination in sensitive PCR applications.