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| Sample Collection and Submission |
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Guidelines for collecting and submitting non-human DNA samples
Sample collection from a crime scene should be carried out by a trained Scene of Crime Officer (SOCO). Where this is not possible, it is important to adhere to the following guidelines for the collection and delivery of forensic samples for DNA analysis.
There are two key considerations when collecting and delivering samples for DNA forensic analysis:
1 maintaining a chain of custody
2 preserving the DNA contained in the sample
Chain of Custody
In order for any sample to be used as evidence in a court of law, it must remain within a strict chain of custody from the point of sampling through to the forensic laboratories in which it will be analysed. The fewer people involved in a chain of custody, the less likely it is to be broken. Samples need to be numbered and sealed in containers that carry all the information relating to the sample. Transfer of samples between persons needs to be documented and signed by both parties.
Wildlife DNA Sampling Kits
WDNAS produces sampling kits for the recovery of DNA from crime scenes. The kits contain materials and equipment for takiDNA Testing Kitng a range of different samples as well as instructions for use in the field. They have been accredited for use by the PAW forensics working group and are currently used by UK Police, HMRC and RSPCA officers. For further information about ordering sampling kits, please contact us directly.
Preservation of DNA in samples
Where a SOCO or sampling kit are not available, it is important to consider how best to preserve DNA in samples. Genetic material is fragile and particularly easily damaged if stored in moist or light conditions. To prevent moisture from promoting the degradation of DNA, samples should either be completely dried, or stored in 70-80% ethanol. The following guide indicates how to store different types of sample for subsequent DNA analysis.
| Sample Type |
Dry storage |
Wet storage |
| Animal Tissue |
Desiccate with very gentle heat |
70-80% ethanol |
| Blood |
Air dry (for stains)
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Store in heparin |
| Hair and Feather |
Air dry |
70-80% ethanol |
| Faeces |
Desiccate with very gentle heat |
70-80% ethanol |
| Swabs |
Air dry |
Do not store wet |
Containers
For dry samples:
Avoid using plastic containers where possible, as these will prevent the release of residual moisture from the sample or air. Where plastic cannot be avoided, use a desiccant such as silica crystal pouches to remove moisture.
For ethanol:
Use a solution of between 70% and 80% ethanol. Adjust the volume of ethanol to the size of the sample, make sure that the sample is fully immersed and saturated. Ensure that the container is completely sealed. Avoid using ink to record sample data on the container, mark in pencil.
Delivery:
Forensic samples can only be received by prior arrangement.
For delivery, please send to the following address:
Sample Controller
Tepnel Research Products and Services
Appleton Place
Livingston
EH54 7EZ
United Kingdom
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