FAQs
How long can saliva for each analyte be stored before use?
We recommend all saliva be frozen as soon as possible after collection. Some analytes have been shown to be relatively stable when stored at room temperature, however, sample specific differences have been observed. At a minimum we recommend samples, once collected, be refrigerated at 4°C immediately after collection and transferred to -20°C as soon as possible.
How long can saliva for each analyte be stored frozen at -20 °C or below?
Once frozen in cryovials at –20°C or below, the stability of analytes in saliva is no different than the long term stability of analytes in other traditional biological specimens. Theoretically, storage at -20°C or below is the best and most economic option for the storage of saliva samples in biorepositories. We do not recommend long term storage, beyond 6 months, of samples collected with swabs unless sample is transferred to cryovials.
Can I use stimulants to collect saliva?
The use of stimulants to increase saliva production is not recommended as it can lead to artificially high or low levels for some analytes. In extreme cases, such as elderly populations, or studies with participants who are unable to generate sufficient saliva due to medication side-effects, it is considered acceptable to use visual aids, such as pictures of food to help increase salivation, or the use of olfactory stimulants, such as extracts of lemon oil or orange oil inhaled.
Schwartz, E., Granger, D. A., Susman, E. J., Gunnar, M., & Laird, B. (1998). Assessing salivary cortisol in studies of child development. Child Development, 69, 1503-1513. PMID 9914636
Can I use protease inhibitors for saliva collection with Salimetrics swabs?
Salimetrics has not validated the use of protease inhibitors with the assay kits. If you determine a need for protease inhibitors in saliva samples, we recommend you validate the use of these inhibitors prior to the study sample collection to ensure that there is no impact on the results of the assay.
How do I aliquot samples?
In this video we demonstrate how to split saliva samples via aliquoting. We demonstrate proper technique and also review workspace prep and sample organization.
Why do I have to freeze and centrifuge saliva samples before testing them?
Whole saliva contains glycoproteins known as mucins, which give saliva its thick and sticky consistency. Using fresh saliva for quantitative estimations leads to inconsistent results due to these mucins. Once frozen, mucins will precipitate and fall out of solution. Subsequently, thawed samples, when centrifuged will contain a pellet with the precipitated mucins, and other substances such as cell debris and food particles will sink to the bottom, while the supernatant will be a clear, water-like consistency, and easier to handle. Results obtained with this cleared saliva sample are more accurate and consistent.
For home saliva collection, is it OK to have saliva frozen in the home and mailed overnight to a central collection location?
If shipping on dry ice is not possible/practical, then they should be frozen and shipped frozen using 3 ice packs in a u-line insulated cooler for 36 hour delivery. We advise including a temperature tracking device in your shippers. Salimetrics recommends FedEx overnight shipping.
What collection device would you recommend for my study?
Choosing the right sample collection device is critical to high quality results. There are multiple variables that need to be considered prior to choosing the collection device appropriate to your study design and for your population. A list of collection methods for certain participant groups and validated by analytes is available at Saliva Collection Methods & Devices.
Why don’t you recommend Sarstedt salivettes anymore?
Internal testing suggests a higher degree of variability between analyte concentrations when sample is collected by passive drool or the SalivaBio swab and compared to Salivettes – both the cortisol specific Salivette (blue top) or the cotton Salivette (white top). We believe that any swab used to collect a saliva sample must have results consistent with passive drool, the gold standard of the saliva collection, and our data indicates that Salivette derived data is significantly different from that obtained using the SalivaBio Swabs. For more information, you may review the data presented in the Rigor and Reproducibility (Part 2): How Good Are Your Saliva Samples? bulletin.
To ensure precision and consistency in saliva based research, we recommend the use of SalivaBio Swabs for saliva collection when swab collection is required.
How should I dispose of saliva samples after testing?
Disposal of saliva samples is Institute specific. Please check with the EHS department at your organization to determine the regulations associated with saliva disposal. Saliva is considered a Class II biohazard and disposal will be consistent with policy determining Biohazardous Waste at your organization.
How many analytes can be analyzed from one sample?
A single saliva sample can be used for the measurement of multiple analytes. The number of analytes tested depends on the type of analyte to be tested. Please call us for sample volume requirements specific to your study.
Do medications interfere with cortisol?
Please refer to the following articles for medication and its impact on cortisol levels:
Granger DA, Hibel LC, Fortunato CK, Kapelewski CH. (2009) Medication effects on salivary cortisol: tactics and strategy to minimize impact in behavioral and developmental science. Psychoneuroendocrinology. 34(10):1437-48. PMID: 19632788
Hibel LC, Granger DA, Kivlighan KT, Blair C. (2006) Individual differences in salivary cortisol: associations with common over-the-counter and prescription medication status in infants and their mothers. Hormones and Behavior. 50(2):293-300 PMID: 16682032
In addition, follow the recommendations in the Salimetrics Saliva Collection Handbook for additional advice