ABSTRACT
Residues of an organic substance administered to or ingested by an animal consist of the substance itself (generally called the parent compound) and its transformation products (metabolites). The nature of residues can vary from one animal tissue to another. For example, liver may contain residues different from those found in muscle. Target organs (tissues) are defined for control purposes and, in a given tissue, a target compound, which is not necessarily the parent compound, is assayed.
