[Hemolytic activity of tensides--determination of the interaction between O/W- and W/O-surfactants]

Using an newly-developed haemolysis method it is possible to determine quantitatively a KLH-surfactant 3000 that exists unbound in the aqueous phase of a tertiary system containing W/O-surfactants. The method depends on membrane damage of erythrocytes and is therefore a measure of the skin acceptability of a sample. The selective analysis technique works without previous preparation of complex mixtures that could lead to errors. It gives decisive evidence that KLH-surfactant 3000 that is fixed to either the W/O-surfactants or the lipid/water interface causes no membrane damage compared with free coconut/fatty acid. Haemolysis studies show that the fraction of KLH-surfactant 3000 dissolved in the aqueous phase decreases strongly with increasing amount of cetylstearyl-alcohol (CSA) up to a ratio of fatty alcohol/KLH-surfactant of approx. 0.3:5. In this range the fatty alcohol binds ten times as much O/W-surfactant in the mixed surfactant system. Further addition of CSA above the ratio 0.3:5 cause relatively little additional fixation of coconut/fatty acid, and the co-surfactant crystallises out. The rate of binding of a 1:1 mixture of CSA and glycerolmonostearate (GMS) is comparable with that of pure fatty alcohol. This mixtures also shows reduced tendency to crystallisation.