Embodiments of the disclosure provide a method of determining the presence of a hydrocarbon in an aqueous medium used for secondary oil recovery. The method includes the step of introducing the aqueous medium into a subterranean hydrocarbon formation to displace hydrocarbons. The method includes the step of retrieving an aqueous sample from the aqueous medium introduced into the subterranean hydrocarbon formation. The method includes the step of cooling the aqueous sample such that the aqueous sample is in a solid state. The method includes the step of exposing the aqueous sample to an electromagnetic wave at a microwave frequency such that a scattering response is induced from the hydrocarbon included in the aqueous sample. The method includes the step of determining permittivity of the hydrocarbon based on the scattering response.