Apparatus for determining the amount of a surfactant dissolved in a solution

An apparatus for determination of an amount of a surface active substance, comprising:

• a trough having at least a cell which contains a surface active substance solution in which a surface active substance exhibiting a surface activity is dissolved;
• a movable stage provided under said trough for mechanically supporting and moving said trough in a horizontal plane;
• a stage controller coupled to said stage for controlling movement of said stage;
• a dropping means provided over said trough for dropping a monomolecule film developing solution onto a surface of said surface active substance solution in order to form a monomolecule film on said surface of said surface active substance solution;
• at least a movable partition plate provided over said trough for partitioning said surface active substance solution into a primary part and a subordinate part;
• a partition plate controller coupled to said movable partition plate for controlling movements of said movable partition plate;
• a measuring means provided over said trough for measuring a surface tension of said monomolecule film on said primary part of said surface active substance solution;
• a computing means electrically coupled to at least said measuring means for receiving information of said surface tension measured in order to compute a concentration of said surface active substance and then find a content of said surface active substance on the basis of said computed concentration,
• wherein said computing means computes a position of said movable partition plate, and
• wherein said partition plate controller is electrically coupled to said computing means for receiving information of said computed position to move said movable partition plate in order to adjust a surface area of said primary part so that before an initiation of a subsequent surface tension measurement, said surface tension of said monomolecule film is controlled at a predetermined value.