Analytical test methods for organic detergents

Abstract

Wetting as a l~'unction of pH and Chain Length. Wetting action is another area in which ampholytics, as such, probably cannot compete directly with less expensive products. However, in conjunction with other properties for a specific application, wetting becomes a definite plus feature. In general, wetting action of an ampholytic follows the typical pattern of being quite specific as regards chain length with the optimum for the N-fatty fl-aminoproplonates occurring at a chain length of about Cm at which chain length is exhibited an almost instantaneous wetting time. The pit functionality of wetting action follows the general trend of that of the majority of the other performance characteristics, going through a minimum in the isoelectrie range.Surface and Interracial Tension Data. The N-fatty ~-aminopropionates exhibit a very high degree of surface and interfacial tension lowering. When the fatty group is essentially 12 carbons in length, interracial tensions are well below 2 dynes per em. at concentrations of 0.1% active. Likewise, at 0.1% active concentration, this product (sodium N-dodeeyl fl-aminopropionate) will exhibit a surface tension of about 25 dynes per cm. As wlth wetting, these values are more or less independent of pH except in the isoelectric range.Compatibility with Other Surfaetants. In the complex realm of multi-component formulations, ampholytic surfaetants have very interesting possibilities. In general, ampholytics are compatible over wide ranges of detergent ratios and with anionic, non-ionic, and cationic surfactants. Cationic surfactant compatibility is probably the most interesting. "Virtually all anionic surfactants will almost quantitatively precipitate or inactivate cationic detergents, especially quaternary ammonium compounds. However, even in ratios as high as 16 parts of sodium N-alkyl fl-aminoproplonate and 1 part quaternary, the germicidal effectiveness of the quaternary is virtually unaffected. Hence it is possible to formulate a quaternary with an ampholytic in its anionic form and enjoy the advantages of both cationic and anionic behavior.[