q20 



Xanthene Dyes 



RHODAMINE B 



181 



c. I. NO. 749 



Synonyms: RJiodamine 0. Brilliant pi?ik B. 



CH3CH, 



CH.CH, 



N 



C28H31X2O3CI; Mol. Wt. 479.001 

 {A basic dye; absorption maxima about 556.5, [517]) 

 Solubility at 26°C: in water 0.78%; in alcohol 1.^7% 



A rhodamine, probably the above dye, has been used by Gries- 

 bach with osmic acid to fix and stain blood simultaneously; by 

 Ehrlich as a component of *'neutral" stain mixtures; also for his- 

 tological work in contrast to methylene blue; and by others 

 in contrast to methyl green. (See Krause, 1926-7, p. 2023.) Al- 

 though these early users were not always careful to specify which 

 rhodamine had been employed in their work, rhodamine B has 

 been definitely specified by later workers, e.g.: by Houcke (1928) 

 as a stain for glandular tissue, when mixed with methylene blue; 

 by Strugger (1938) as a vital stain for Allium epidermis, calling 

 attention to its fluorescence under ultraviolet light; by Monne 

 (1939) in studies on the Golgi apparatus; by Levaditi et al. (1940), 

 as a fluorochome of value in virus studies; by Metcalf and Patton 

 (1944), as a fluorochrome for use in insect histology; and by Fred- 

 erick (1941), as a microchemical reagent for the estimation of 

 antimony. It seems to be coming into more common use at pres- 

 ent, thanks in good part to its fluorescent properties in ultraviolet 

 light. 



As a rhodamine is not infrequently specified without a shade 

 designation, it is sometimes not possible to be sure that the above 

 dye is intended. If not, the following is the dye most probably 

 indicated. 



