Best Practices for Saliva Collection
- When preparing for any study involving saliva collection, be sure to read up on the best collection time for your analyte based on circadian rhythms and – if your study involves interventions or manipulations – average response and recovery times (see our Analyte Guides and/or refer to the literature).
- Note that if the literature lacks guidance or rules of thumb for the optimal collection times for an analyte you wish to measure, we strongly recommend you conduct a pilot study.
- Understand the confounds that you need to eliminate. These vary by analyte, so you will need to refer to the literature for guidance.
- We recommend including the following data collection guidelines for all saliva-collection studies:
- Participants should not eat anything within 1 hour of sample collection.
- Participants should not brush or floss their teeth within 1 hour of sample collection.
- Participants should not drink anything other than water within 30 minutes of sample collection.
- Participants should not have dental work performed within 24 hours of sample collection.
- Participants should be told to avoid wearing lipstick or lip gloss to their testing session.
- Participants should avoid consuming alcohol, caffeine, nicotine, or medications within 12 hours of sample collection.
- If this is not possible, researchers should document the use of these products.
- Researchers should ask participants to report on recent vigorous exercise (recency of exercise and vigorousness) and on their dental and oral health.
- Participants should rinse mouth with water to remove any oral residue prior to sample collection. After rinsing, participants should wait 10-20 minutes before providing sample to
avoid dilution. Note that that the rinsing protocol must be standardized between all participants (e.g., it is unwise to have one P wait 10 minutes and another to wait 20).
Sample Collection (All Methods)
- Saliva samples are collected by participants themselves, so communication is key to getting a high quality sample. To ensure a high-quality sample:
- Participants should be clearly instructed on the collection procedure and required sample volume.
- Give participants ample opportunity to ask any questions before collection begins.
- Researchers should visually inspect collected samples to ensure an adequate volume has been collected and that the sample is free from contamination.
- Samples visibly contaminated with blood should be discarded and recollected.
Most analytes are best assayed from passive drool. However, in some cases, it may be appropriate to use a validated absorbent swab method. Refer to the literature for guidance on the techniques that have been validated for your analyte.
Use only high-quality polypropylene collection tubes and vials to store samples; vials should seal tightly, be externally threaded, and be able to withstand temperatures as low as -80ºC.
All samples must be appropriately and clearly labeled during sample collection. We recommend labeling without identifying participant information (please see our Labeling Guidelines and downloadable label templates).
Passive Drool Procedures
Collect at least 2mL of passive drool from each participant, at each time point (if you are assaying multiple analytes, more saliva may be necessary).
What is passive drool, exactly? With passive drool, the saliva is allowed to pool at the bottom of the mouth and then eased into a collection device directly, or with a straw. This is different than the type of saliva that you gather when you are actively trying to spit (which is accomplished by sucking together whatever saliva and mucous are in the mouth). This latter method gets a lot of mucous in the sample, which can make it unusable. To ensure you capture passive drool:
Advise participants to allow saliva to pool in mouth. Then, with head tilted forward, gently guide saliva into the collection tube either directly or with a straw (depending on your preferred collection procedure).
- Explain to participants that they are not to forcibly spit or blow into the collection tube. If the sample is made up primarily of mucous (instead of drool), it may not be usable.
Absorbent Swab Procedures
Collection procedures vary depending on the swab kit you’re using. Read the instructions provided by the manufacturer carefully and ensure that you collect sufficient volume and follow the recommended collection procedure for the analyte you intend to measure.
Immediately after collection, freeze samples at or below -20ºC.
If freezing is not immediately possible, samples can be refrigerated for up to 2 hours at 4ºC before freezing. This prevents bacterial growth and degradation of salivary molecules.
Samples stored for more than 4 months should be frozen at -80ºC.
It is recommended that tubes be organized into cryostorage boxes before storing or shipping.
Minimize freeze-thaw cycles to maintain sample integrity.
If possible, it is recommended to pipette saliva from collection tubes into microcentrifuge tubes prior to sample freezing.
Important Note For Researchers
Following the Eos BioAnalytics Sample Collection Guidelines is crucial to ensure the highest quality sample. If you fail to comply with the collection, handling, storage, and shipping guidelines outlined here and in our Best Practices Guides, we cannot guarantee the quality of your results or the usability of your samples. In the event that we receive contaminated or otherwise compromised samples, a scientist from our research team will contact you to discuss analysis options.