The invention discloses methods and devices for rapidly detecting a biological and/or chemical residue in a liquid sample. In some embodiments of the instant invention, a single antenna is generally employed in proximity to an aqueous solution in a disposable cup, with electrical outputs being recorded by an electrical metering device in communication with the single antenna. Commercial plastic cups may be used for detection of electric fields related to cleanliness of water samples. General and specific target detection may be performed with various embodiments of the instant invention.