1,2,3-Trioctanoyl-rac-glycerol-13C3 is intended for use as an internal standard for the quantification of 1,2,3-trioctanoyl-rac-glycerol by GC- or LC-MS. 1,2,3-Trioctanoyl-rac-glycerol is a triacylglycerol that contains octanoic acid at the sn-1, sn-2, and sn-3 positions. Dietary administration of 1,2,3-trioctanoyl-rac-glycerol increases hippocampal levels of the glycolytic metabolites glucose 6-phosphate, fructose 6-phosphate, and β-hydroxybutyrate and the seizure threshold in the 6 Hz psychomotor seizure test in mice.1 Formulations containing 1,2,3-trioctanoyl-rac-glycerol have been used in cosmetic products as thickening and skin-conditioning agents.