HEMOLYTIC-ACTIVITY OF TENSIDES - DETERMIN ATION OF THE INTERACTION BETWEEN O W-SURFACTANTS 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 aqueo us phase of a tertiary system containing W/O-surfactants. The method d epends on membrane damage of erythrocytes and is therefore a measure o f the skin acceptability of a sample. The selective analysis technique works without previous preparation of complex mixtures that could lea d to errors. It gives decisive evidence that KLH-surfactant 3000 that is fixed to either the W/O-surfactants or the lipid/water interface ca uses no membrane damage compared with free coconut/fatty acid. Haemoly sis studies show that the fraction of KLH-surfactant 3000 dissolved in the aqueous phase decreases strongly with increasing amount of cetyls tearyl-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 CS A 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 c omparable with that of pure fatty alcohol. This mixtures also shows re duced tendency to crystallisation.