|Jmol-3D images||Image 1|
|Molar mass||960.81 g mol−1|
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
T-1824 or Evans Blue, often incorrectly rendered as Evan's Blue, is an azo dye which has a very high affinity for serum albumin. Because of this, it can be useful in physiology in estimating the proportion of body water contained in blood plasma.
Evans blue is also used to assess the permeability of the blood–brain barrier to macromolecules. Because serum albumin cannot cross the barrier, and virtually all Evans Blue is bound to albumin, normally the neural tissue remains unstained. When the BBB has been compromised, albumin-bound Evans blue enters the CNS. It fluoresces with excitation peaks at 470 and 540 nm and an emission peak at 680 nm. 
It was named after Herbert McLean Evans, an American chemist.
- Physiology at MCG 7/7ch02/7ch02p17
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