LEONARD L. JANSEN 



Agricultural Research Service, USDA 

 Beltsville, Maryland 



Physical-Chemical Factors of Surfactants 



in Relation to Their Effects on the 



Biological Activity of Chemicals 



It is not possible to state the exact manner in which wetting agents 

 or other types of surfactants may be employed to increase the effec- 

 tiveness of biologically active materials. In the first place, the term 

 surfactant, which is a contraction of surface active agent, denotes 

 any organic substance which possesses surface active properties. A 

 great number of surfactants have appeared over the past 30 years. 

 Primarily, the big boom started with the expansion of the soap in- 

 dustry immediately after World War I. Development of synthetic 

 detergents was accentuated greatly during World War II. During 

 the past ten years there has been a tremendous boost in the number 

 of surface active agents of all types. The variety of commercial appli- 

 cations of surfactants is almost phenomenal. From the usage stand- 

 point, surfactants may be classified as soaps, detergents, wetters, emul- 

 sifiers, dispersants, spreaders, thickeners, solubilizers, etc. In this paper 

 are presented some of the physical-chemical properties of surfactants 

 which I believe warrant consideration in future experimentation. It 

 also calls attention to a great bulk of information which has been 

 brought together and summarized by Schwartz and Perry (1). This 

 book brings up to date most of the surfactant information as it ex- 

 isted up to 1947. Developments which occurred from 1947 to 1957 

 are summarized in a second volume by Schwartz, Perry, and Berch 



(2)- . . , 



We have previously examined some of the important biological 



applications of surfactants. Dr. Phinney has demonstrated greatly 



enhanced uptake of gibberellic acid from surfactant solutions. Crosby 



and Vlitos have found certain naturally-occurring long-chain alcohols 



and acids, which undoubtedly exhibit some surfactant properties, to 



have growth stimulatory activity. In the same manner, Stowe has ob- 



[813] 



