ChEBI

Any minor or unwanted substance introduced into the environment that can have undesired effects.

A molecular entity capable of donating a hydron to an acceptor (Bronsted base).

A xenobiotic (Greek, xenos "foreign"; bios "life") is a compound that is foreign to a living organism. Principal xenobiotics include: drugs, carcinogens and various compounds that have been introduced into the environment by artificial means.

A reagent used to improve selectivity in chromatographic analyses or separations, e.g. by formation of a derivative or by modification of the mobile phase.