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Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysts


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The QAS outlines facilities requirements with the intent to minimize contamination risks. The application of the PCR process to forensic DNA analysis has dramatically improved the technological abilities in the field. The use of PCR does, however, require that laboratories have appropriate facility design and procedures in place to minimize the risk of contamination. QAS standard 6.1.4 requires the following:

  • The laboratory must be designed to provide adequate security and minimize contamination. Note 1
  • Access to the laboratory must be controlled and limited. Note 2
  • Evidence examinations, liquid sample examinations (for offender laboratories), DNA extractions, and PCR setup must be conducted at separate times or in separate spaces. Note 3
  • Amplified DNA product must be generated, processed, and maintained in a room(s) separate from the evidence examination, DNA extractions, and PCR setup areas. Note 4
  • For offender laboratories, if a robotic workstation is used to carry out DNA extraction and amplification in a single room, the laboratory must demonstrate that contamination is minimized and equivalent to that when performed manually in separate rooms. Note 5
  • The laboratory follow written procedures for monitoring, cleaning, and decontaminating facilities and equipment. Note 6

[1] The laboratory must have documented and well-understood procedures for security, and use procedures that minimize contamination.

[2] Additionally, the laboratory must be secured and controlled in a manner to prevent access by unauthorized personnel and limit access to authorized personnel.

[3] The laboratory's approach to sample processing for PCR-based procedures (extraction and amplification) must demonstrate a separation in time or physical space for each activity. This can be accomplished through a combination of clearly written technical procedures, casework notes, and/or personal observation. The laboratory's design must demonstrate that evidence flow, through the various steps of DNA processing, does not compromise the integrity of the sample. The amplification room must be enclosed with walls from the floor to the ceiling and door(s) for passage, and the amplification room(s) must physically separate amplified DNA from all other areas of the laboratory by maintaining doors in the closed position.

[4] When robotic workstations are used to carry out DNA extractions through PCR setup on casework samples, a single room may be used. Internal validation must show that if contamination occurs, it is minimized, addressed, and less than or equivalent to that observed when these procedures are performed manually in separate rooms.

[5] Robotic workstations may be used to carry out DNA extraction through amplification in a single room provided that they are separated from the sample extraction and sample amplification areas and that it can be demonstrated through internal validation that if contamination occurs, it is minimized, addressed, and less than or equivalent to that observed when these procedures are performed manually in separate rooms.

[6] A laboratory may employ a variety of methods to monitor its facilities, such as the use of appropriate controls in the analysis process. Whichever approach(es) the laboratory selects to use, the method(s) must be documented. This may be accomplished through a variety of ways at the discretion of the laboratory.

A very generic schematic of a laboratory layout that would comply with standards to prevent contamination. Note the one-way flow of the samples. Additional rooms may be present for reagent preparation, film development, computer use, etc. Each area should have dedicated equipment, reagents, and PPE.

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