University of Michigan Psychology Department
Information on Assays
Before any client submits SALIVA samples for analysis, they must first understand the specific details of the particular assay they would like our lab to conduct. Important details include the maximum number of samples per kit, the minimum sample volume, acceptable collection methods, and any pre-processing steps that are required prior to bringing the samples to the lab for analyses.
Information for Salivary Assays
|Assay||Maximum Samples/kit||*Minimum sample volume||Acceptable Collection Method||Pre-processing|
|Cortisol EIA||38||100 Ál||Salivettes, passive drool||None|
|Estradiol EIA||38||250 Ál||Passive drool||None|
|Progesterone EIA||38||150 Ál||Passive drool||None|
|Testosterone EIA||38||100 Ál||Passive drool||None|
|DHEA EIA||38||150 Ál||Passive drool||None|
|DHEAS EIA||39||250 Ál||Passive drool||None|
|SIgA EIA||38||100 Ál||Passive drool||None|
|Melatonin RIA||90||1 ml||Salivettes||None|
|Cortisol RIA||235||1 ml||Passive drool||**Freeze-thaw cycles|
|Estradiol RIA||235||2 ml||Passive drool||**Freeze-thaw cycles|
|Progesterone RIA||235||1 ml||Passive drool||**Freeze-thaw cycles|
|Testosterone RIA||235||1 ml (male)||Passive drool||**Freeze-thaw cycles|
|2 ml (female)||Passive drool|
Maximum samples/kit: Maximum number of samples that the most cost effective reagent kit can analyze. It is advisable that researchers provide samples in multiples of this number in order to optimize assay costs.
Minimum sample volume: Minimum amount of mucosaccharide-free saliva for each sample in order to run analyses (see below).
Acceptable collection method: Salivary samples are generally collected via (1) salivettes or comparable absorption devices, or (2) passive drool. For both collection methods, a processing step is necessary to separate the mucosaccharides from the rest of the saliva. While salivettes are often considered to be more user-friendly, passive drool is considered the method that provides the most reliable results. The use of salivettes not only provides less total sample, but more importantly, introduces substances that interfere with the assay, producing results that are inaccurate. For this reason, we recommend that salivettes only be used when researchers are interested in either the cortisol EIA or the melatonin RIA. In all other instances, the Core Assay Facility can process your results, but we cannot assure you of their scientific value.
Pre-processing steps: Whether collecting via salivettes or passive drool, all samples must be subject to processing steps prior to assay in order to separate mucosaccharides from the rest of the saliva. If you are collecting via salivettes, that step will be conducted by CAF. However, if you are collecting via passive drool, we require that you subject your samples to two freeze-thaw cycles prior to bringing them in for analyses. For each freeze-thaw cycle, just take the samples out of the freezer, wait until they are thawed, and put them back in the freezer. All samples should be ordered (left to right, front to back) and contained within a rack (not a bag or a cardboard box).