An apparatus and method are disclosed to detect foam above a liquid sample in a sparge vessel, and disrupt any foam that may exist. The foam sensor includes an optical emitter and optical sensor coupled to a sparge vessel above the level of the liquid sample. Foam is detected if the light beam is attenuated or blocked. The foam disrupter provides thermal energy to raise the temperature of a surface in the sparge vessel to break up the foam, which may condense on the walls of the sparge vessel.