Water-Insoluble Complexes of Simple Aryl Sulphonates and Gelatin

Abstract

THE combination of organic anions such as alkyl sulphates, acid dyes, and commercial detergents with proteins has been the subject of considerable published work^1–7. When alkyl sulphates (not less than ten carbon atoms in the paraffin chain), such detergents as ‘Teepol’ (secondary alkyl sulphate) or alkyl–aryl sulphonates combine with gelatin, complexes may be formed which are insoluble in water or aqueous electrolytes. As the ratio of anion to gelatin is increased from zero, complexes of decreasing water-solubility are formed until a certain proportion is reached (value depending upon pH, electrolyte, concentration of electrolyte, etc.), corresponding with the complex of minimum water-solubility. Such a complex is found also to have maximum solubility in organic solvents^1,5. Further increase in anion to gelatin ratio beyond this value causes peptization.