The air-water interface is a little investigated field of the electrolyte structure, however, interesting effects occur there. In this work three different systems were investigated with the focus on the change in structure at the interface. I applied sum-frequency generation (SFG) spectroscopy among other methods to monitor the surface arrangement of the dissolved molecules, surface active lipids and of the interfacial water. With this it is possible to draw a conclusive picture of the interfacial structure of the different systems.