Animal by-products result mainly from the slaughter of animals for human consumption, the production of products of animal origin (such as dairy products), the disposal of dead animals, and disease-control measures. Regardless of their source, they pose a potential risk to public and animal health and the environment. This risk needs to be adequately controlled, either by safe disposal of such products, or by their utilization, provided that strict conditions are maintained to minimize the health risks involved. Animal by-products are classified into categories that reflect the level of risk to public and animal health arising from those by-products (Cat. 1, 2 and 3). According to Commission Regulation (EU) No 142/2011, in processing plants for the processing of Category 1 or 2 material, derived products shall be permanently marked with glycerol triheptanoate (GTH). The minimum content of marker in target materials is 250 mg/kg of fat. For the determination of glycerol triheptanoate in dry meat, bone meals, rendered fat and soil adjuvants, gas chromatography technique and mass spectrometry detection are used.