Quinone-imine Dyes 121 



k30 NILE BLUE SULFATE C. I. NO. 913 



Synonym : Nile blue A . 



There are two products sold at present under this name, one is 

 a dimethyl aminophenol derivative, the other derived from diethyl 

 aminophenol. The formula of the latter is: 



CH3'CH2 



N 

 / \/\_0_/\=NH2 



N 



(SO^)^ 



(C2oH2oN30)2S04; Mol. Wt. 732.828 

 {A basic dye; absorption maxima 63o-G4o) 



A spectral graph of brilliant cresyl blue, compared with resa- 

 zurin and Nile blue sulfate, is given in Fig. 13, p. 118. 



The use for which this dye is best known to the biologist is the 

 Lorrain Smith fat stain (Smith and Mair, 1911). In this pro- 

 cedure the dye is boiled with dilute sulfuric acid, and thus hydro- 

 lyzed, with the introduction of oxygen in the place of the radical 

 NH2 (S04)5, in other words producing a new dye of the class known 

 as oxazones. This oxazone dye is red, and is fat-soluble. Nile 

 blue sulfate itself, on the other hand, is not fat-soluble but com- 

 bines readily with fatty acids. As a result the technic serves to 

 distinguish between the free fatty acids in histological material 

 and the neutralized fats, the former staining blue, the latter red. 

 Knaysi (1941), however, calls attention to the fact that other dyes 

 (e.g. neutral red or methylene blue) can be similarly employed. 



Nile blue sulfate is used unaltered for staining living tadpoles 

 previous to making transplants, in order to distinguish the grafts, 

 also as a supravital stain for embryos (Detwiler, 1917) and as a 

 vital stain for hydrae (Weimer, 1927), protozoa (Carter, 1933), 

 yeasts (Gutstein, 1932) and amphibian eggs (Wintrebert, 1932). 



kland (1939) recommends it for staining bone sections, Tarao 

 (1940) for histochemical studies of the Golgi apparatus. Foshay 

 (1931) employs it for staining bacteria in tissues. The dye has 

 been employed in culture media, containing emulsified fat, for the 

 purpose of recognizing lipolytic bacteria; see Hammer and Collins 

 (1934). Loosanoff (1937) finds it useful in marking starfish for 

 identification. 



For technic of Smith and Mair's stain for fats, see Staining Procedures, p. ID3-I8. 



