Does saliva fluoresce? If it does, what nm is necessary to accurately identify the fluid?

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selmasharafaz | College Teacher | (Level 3) Adjunct Educator

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Saliva does exhibit flourescence.

Saliva stains are important sources of forensic evidence. Dried saliva is hard to detect. Fluorescent spectroscopy is a rapid and non-invasive method to detect saliva stains from dried samples as well as samples on human skin.

When excited at 282 nm, if saliva is present in the sample, the peak emission would be observed in the range of 345 - 355 nm. A water control would give peak emission spectrum at 362 nm. The technique is highly sensitive and cost effective.

The enzyme, α amylase (alpha amylase) in saliva gives the characteristic emission spectrum at 345 - 355 nm when excited at 282 nm. The aromatic amino acid, tryptophan, one of the most important amino acids in α amylase, is responsible for this fluorescent emission.