If you collect DNA specimens – buccal cell, blood, or touch – you know it’s essential that the specimen is dry before packaging for transport or storage. But why is that important?
A moist specimen will support bacteria and molds that degrade DNA. Thoroughly dried, the DNA will remain a useful specimen. Refrigeration also protects the cellular specimen – so dry and cold is best for long-term storage.
Selecting a Swab for DNA Collection
There are a few points to keep in mind when selecting a swab for the collection of DNA.
First, the collection tool must be easy to use, and have been manufactured in a controlled environment and certified as DNA-free. Second, a swab for a moist DNA specimen collection must allow for the specimen to dry.
Air drying is the easiest and most common method. But the time needed to allow for adequate drying depends on the humidity of the environment. To assure the specimen has the time needed to dry, it is best to protect the swab in a paper wrapper or swab box, or better yet, in a vented rigid cover or tube.
Preserving Sample Integrity
The simplest of these DNA swab styles is one with a vented cap, like the Cap-Shure®, which Puritan brought to market in 2005. This product protects a cotton or polyester flock swab tip in a vented cap with a flip top, sterile packed in a permeable wrapper.
Simply flip the top, slide the shaft of the swab through the cap’s vented base, collect the specimen, then slide the swab back into the cap. Close, label, and return to the original wrapper, or pack it in a specially designed Cap-Shure swab box (available from Raysics®) or a paper envelope. The swab will continue to dry in transport or storage until processed, whether processing is the same day or years down the road.
Vented Transport Swab Tubes Promote Drying
LOCI Forensics in the Netherlands developed a vented transport swab tube with an air-breathable filter, to allow for drying while eliminating the likelihood of contamination being introduced from the environment. In 2010, Puritan, in collaboration with LOCI, introduced the FABUSA style – a basic cotton on wood swab packed in the LOCI FAB-SWAB type tube.
This swab is very highly regarded in the forensics community, as it provides a simple and easy-to-use swab that assures adequate drying and secure transport. The tube is very protective, lightweight, and easy to transport. Since then, Puritan has added other cotton swabs in this specialty tube and, most recently, Puritan’s PurFlock swab.
Dry Transport Systems for Dry Specimens
For dry specimens, perhaps touch DNA evidence that is not moist, consider Puritan’s line of dry transport systems. As all Puritan products for diagnostic specimen collection are protected from contamination in manufacture, these are suitable for the collection and transport of molecular specimens as well as microorganisms. You will find tipped applicators of spun fiber, foam, and flock in this line, in single and double swab packs. Your specimen is safe in a Puritan transport device.