Sure. It is known that many commercial meat producers are already injecting their animals with graphene filled vaccinations. In some places it is now mandated under the guise of needing to protect herds from contagious diseases. Graphene is magnetic. If these animals that have been injected with graphene filled serums or if graphene has been sprayed on the the feed they eat, the graphene in the animal's tissues will react with a strong magnet. Neodymium magnets are super strong relative to their small size, inexpensive, and can easily be stored in a pocket. You can check reactivity to many foods. Crops of corn and wheat as well as many other vegetables are already being sprayed with graphene and other poisons that are absorbed into the plant tissues. Buyer beware!