Oleoyl Ethanolamide-d2 (OEA-d2) is a deuterium-labeled internal standard used in research for the quantification of oleoyl ethanolamide (OEA) in biological samples via mass spectrometry. It enables precise measurement and differentiation of OEA, facilitating studies on the endocannabinoid system and its roles in appetite regulation, lipid metabolism, and inflammation. This compound is applied in metabolic and neurological research to investigate OEA's effects on energy balance and pain perception.