Evans blue

Evans Blue is a dye that is also known as Direct Blue 53 or C.I. Direct Blue 53. It is a diazo dye that was first synthesized in the early 20th century and has been used in a variety of applications, including as a histology stain and in the measurement of blood plasma volume.

History[edit | edit source]

Evans Blue was first synthesized in the early 20th century. It is named after H. M. Evans, a British histologist who first used the dye in his research.

Chemical Properties[edit | edit source]

Evans Blue is a diazo dye, which means it is composed of two nitrogen atoms connected by a double bond. It has a molecular weight of 961.82 g/mol and a chemical formula of C34H24N6Na4O14S4. The dye is blue in color and is soluble in water.

Applications[edit | edit source]

Evans Blue has been used in a variety of applications. In histology, it is used as a stain to highlight certain structures in tissue samples. In medicine, it is used in the measurement of blood plasma volume. The dye binds to albumin, a protein in the blood, and can be measured to determine the volume of plasma in the blood.

In research, Evans Blue has been used to study the blood-brain barrier. The dye is unable to cross the barrier, so its presence in the brain can indicate a breach in the barrier.

Safety[edit | edit source]

While Evans Blue is generally considered safe for use in research and medical applications, it can cause skin and eye irritation. It is also harmful if swallowed or inhaled.