To distinguish different chemical components on a microscopic scale, scanning surface potential microscopy together with scanning force microscopy and lateral force microscopy were applied on a mixed Langmuir-Blodgett film composed of palmitic acid and trifluorated stearic acid. The monolayer was prepared such that both types of molecules form well-separated domains or clusters. The surface potential measurements were carried out in a LiftMode, with the tip far above the sample surface during the potential measurement. It is found that structures of 30 nm in size could still be resolved in the potential contrast.