A buccal swab is a non-invasive method for collecting deoxyribonucleic acid (DNA) by gathering epithelial cells from the inner lining of the cheek. These cells are constantly shed into the mouth and contain a complete set of the individual’s genetic material. This collection technique is widely used in fields like ancestry and genetic health screening, as well as forensic and paternity testing, because it yields high-quality DNA samples.
Gathering Your Materials and Pre-Swab Preparation
Gather the necessary supplies, including sterile buccal swabs, a sterile collection envelope or tube, and disposable gloves. Use a clean, uncluttered workspace to prevent environmental contamination. To ensure DNA purity, thoroughly wash hands and wear clean gloves to create a barrier against external DNA sources.
Abstain from any activity that might introduce foreign DNA or degrade the existing cells. Avoid eating, drinking (other than plain water), smoking, or chewing gum for a minimum of 30 minutes before collection. This allows contaminants to clear from the mouth. Just before swabbing, rinse the mouth vigorously with water for about 30 seconds to remove residual debris and maximize sample purity.
Executing the Swab Collection Technique
Once preparation is complete, carefully remove the sterile swab from its packaging, handling it only by the handle to prevent contamination. The swab tip, often made of flocked nylon or foam, efficiently captures epithelial cells. Rub the swab firmly against the inside of one cheek, known as the buccal mucosa.
Apply substantial pressure to feel a slight resistance, ensuring the swab effectively scrapes cells from the cheek lining without causing pain. Avoid contact with the teeth, gums, or tongue, which can introduce bacteria or non-human DNA that may interfere with analysis. Use a rolling or rotating motion while maintaining firm contact with the inner cheek surface.
Sustain this motion for 30 to 60 seconds per cheek to guarantee a sufficient yield of cells for DNA analysis. Since DNA yield correlates directly with the number of collected cells, perform a thorough swabbing motion. Some kits require swabbing the same cheek multiple times or using a second swab for the opposite cheek to increase the total cell count.
The goal is to collect the maximum number of nucleated cells, which contain the DNA required for testing. After the allotted time, carefully withdraw the swab from the mouth, ensuring the tip does not touch any external surfaces. If a second swab is required, immediately repeat the process on the opposite cheek using a new, sterile swab.
Ensuring Sample Integrity After Collection
After collection, the first step for preserving the DNA is to allow the sample to air-dry completely. Drying is necessary because moisture promotes the growth of mold or bacteria, which can rapidly degrade the collected DNA. While specific drying times vary, air-dry the swab at room temperature for at least 10 to 15 minutes, and sometimes up to an hour.
Place the swab upright in a clean, dry area, with the collection tip exposed to the air. Avoid using accelerated drying methods, such as direct heat or blowing on the swab, which can damage the DNA structure. Once dried, package the swab into the provided sterile collection envelope or tube.
Place the dried swab gently into its final container and seal it completely to protect the sample from humidity or contamination during transit. If the kit requires labeling, fill out the designated area with the donor’s name and the date of collection. Store the sample at room temperature, shielded from extreme heat or direct sunlight, until it is shipped for analysis.