Abstract: In the present invention, we present a robust technical approach of how the use of a modified detector set-up eliminates a complication in relation to the usage of prism-based optical reflectometry in contact with liquid sample suspension. Additionally we disclose how molecular interactions at a solid-liquid interface can be investigated simultaneously using optical reflectometry. combined with other techniques that do not have technical interference with reflectometry when sharing the same solid sensing surface, for instance with a quartz crystal microbalance of some suitable type.