Abstract: Composition, which includes a dye that changes color when contacted with a suitable amount of an organic substance, in conjunction with a matrix, paste, support or web, can indicate visually or photometrically the presence of the organic substance. An organic spill absorbing material may be present. For instance, the dye may be selected from the class of anthracene, azo, anthraquinone, pyrazolone, and quinone dyes, and be hydrophobic and organic oleophilic. For an example, the dye may be Oil Red “A.” The matrix, paste, support or web may include a microfiber cloth, which may be coated with an adhesive for attachment of the dye, and/or include a water-dissolving paper which may envelope the dye. A device for ascertaining whether an organic substance is present includes the dye or composition with the dye at a certain locale, and a light-transmissive pathway in communication with the location and a detection site external the location.