While Luminol is oftenly used for detection of blood around since 1939, another method can also be used to reveal hidden/washed blood stain known as Fluorescein which is also being used around since 1990s.
What is Fluorescein?
Fluorescein is a fluorophore commonly used in microscopy, in a type of dye laser as the gain medium in forensics and serology to detect latent blood stains.
Fluorescein has an absorption max. at 494 nm and emission max. of 512 nm.
It’s Uses In Forensics
It’s a Presumptive test for blood.
It is used in detection of blood remaining after a stain has been cleaned.
It’s sensitivity is 1.105,000 depending upon the dilution rate of the working solution.
Basis Of The Test
Fluorescein is produced Blue–Green fluorescence indicates the possible presence of blood.
Fluorescein react to the iron and proteins found in hemoglobin of blood.
Indication for the Presence of Blood
It will fluoresce when exposed to light at the 420 nm to 485 nm range .
It produces Blue – Green Color if blood is present.
How To Perform This Test ?
Fluorescein does not give the results with household cleaning items. For examples: Bleach.
This test can only be performed in dark room or at night time.