52 



Fundamentals of Auxin Action 



anol, butanol-acetic acid-water (12:3:2), 70% methanol, phenol satu- 

 rated with water, and ligroin saturated with water gave clearly defined 

 spots of indoleacetic acid. For separation of indoleacetic acid from 

 indole, indolepropionic acid, indolebutyric acid, indoleacetaldehyde, 

 indoleethylamine or tryptophan the first two were the best. In 70% 

 ethanol, however, most of the compounds have RfS between .80-92 



TABLE 2 



Color Reactions Useful in the Detection of Indole Compounds 

 (Sen and Leopold, 1954) 



* Color on standing for 24 hours. 



t After treatment with HCIO4 (Tauber, 1948). 



and it is therefore not the ideal solvent. The separation is much better 

 with isopropanol-ammonia-water. This solvent has been used in dif- 

 ferent proportions by many workers, e.g., 16:3:1 (von Denffer et al, 

 1952) or 10:1:1 (Bennet-Clark et al, 1952). Isopropanol may be re- 

 placed by butanol (Luckwill, 1952; Bennet-Clark et al, 1952) or the 

 ammonia may be placed at the base of the tank without being a com- 

 ponent of the developing solvent. 



Although the indole-aliphatic acids are separable with compara- 

 tive ease, most of the neutral compounds have Rj-s between .80-1.00 



