Resazurin (7-Hydroxy-3H-phenoxazin-3-one 10-oxide) is a blue dye, itself weakly fluorescent until it is irreversibly reduced to the pink colored and highly red fluorescent resorufin. It is used as an oxidation-reduction indicator in cell viability assays for bacteria and mammalian cells, and for measuring aerobic respiration and exchange with the hyporheic zone in streams. Usually it is available commercially as the sodium salt.
Resazurin (pH indicator) below pH 3.8 above pH 6.5 3.8 ⇌ 6.5; Resazurin solution has one of the highest values known of Kreft's dichromaticity index. This means that it has a large change in perceived color hue when the thickness or concentration of observed sample increases or decreases.

Chemical Name	Resazurin sodium salt
Synonyms	7-Hydroxy-10-oxy-phenoxazin-3-on,Natrium-Verbindung;7-hydroxy-10-oxy-phenoxazin-3-one,sodium-compound;ResazurinGr;7-sodiooxy-3H-phenoxazin-3-one 10-oxide;DIAZORESORCINOL;RESAZURIN SODIUM;7-hydroxy-3H-phenoxazin-3-one 10-oxide sodium salt;Resazurine;RESAZOIN;REZAZURIN;RESAZURIN NA-SALT;SODIUM RESAZURIN;REISHIMUSHROOM.P.E;Collapse
CAS No.	62758-13-8
Molecular Formula	C12H6NNaO4
Molecular Weight	251.17000
PSA	78.73000
LogP	2.47010

MDL number	MFCD00005036

Appearance & Physical State	dark red crystals with a greenish lustre
Boiling Point	477.2ºC at 760 mmHg
Melting Point	>200ºC
Flash Point	242.4ºC
Water Solubility	soluble
Stability	Stable. Incompatible with strong oxidizing agents.
Storage Condition	Store at RT.

Safety Statements	S26-S36/37/39
HS Code	2934999090
WGK Germany	3
Risk Statements	R22; R36/37/38
Hazard Codes	Xn