Hi there,
I'm developing a saliva steroid immunoassay based test. With my reaction conditions (which dont have anything esoteric in it), we see better performance with saliva that has been stored at 4C for 2-3 days rather than fresh / frozen / centrifuged saliva. Even if the saliva was filtered then stored frozen, thawed and centrifuged, the performance significantly improves if saliva is stored at 4C for some period of time. Any thoughts on why?
Not sure why this got put into Centrifuges. Moderators, please move to Immunoassay / Molecular Biology / Biochemistry related forums. TIA. D.
Interesting finding. Can you explain what you mean by "performance significantly improves" in your next to last sentence.
Thanks for the reply, Anthony.
We repeatedly get better assay sensitivity (in terms of the negative slope of the competitive assay, ie, slope is more negative and hence better for the older saliva) and precision. The starting point is tthe same. It really is bizarre but we've seen it with multiple pools. Of note is that were testing with a Steroid-BSA conjugate that is freshly spiked in and tested so it's not the age of the spike.
Any and all thoughts appreciated!!
D.
Okay thank you. One of the things we have found as a factor in our assays is the particulate matter in the saliva. Sometimes this is protein from the insider of the mouth, sometimes just food particles. This can really interfer with some of our assays. We always centrifuge our saliva and perceptiate out such large particles before we freeze it for later analysis.
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