Octanoic acid-d15 is intended for use as an internal standard for the quantification of octanoic acid by GC- or LC-MS. Octanoic acid is a medium-chain saturated fatty acid. It has been found in Teleme cheeses made from goat, ovine, or bovine milk.1 Octanoic acid is active against the bacteria S. mutans, S. gordonii, F. nucleatum, and P. gingivalis (IC80s = <125, <125, 1,403, and 2,294 μM, respectively).2 Levels of octanoic acid are increased in the plasma of patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, an inborn error of fatty acid metabolism characterized by hypoketotic hypoglycemia, medium-chain dicarboxylic aciduria, and intolerance to fasting.3,4

|1. Mallatou, H., Pappa, E., and Massouras, T. Changes in free fatty acids during ripening of teleme cheese made with ewes', goats', cows' or a mixture of ewes' and goats' milk. Int. Dairy J. 13(1-3), 211-219 (2003).|2. Hyang, C.B., Alimova, Y., Myers, T.M., et al. Short- and medium-chain fatty acids exhibit antimicrobial activity for oral microorganisms. Arch. Oral Biol. 56(7), 650-654 (2011).|3. Onkenhout, W., Venizelos, V., van der Poel, P.F.H., et al. Identification and quantification of intermediates of unsaturated fatty acid metabolism in plasma of patients with fatty acid oxidation disorders. Clin. Chem. 41(10), 1467-1474 (1995).|4. Rinaldo, P., O'Shea, J.J., Coates, P.M., et al. Medium-chain acyl-CoA dehydrogenase deficiency. Diagnosis by stable-isotope dilution measurement of urinary n-hexanoylglycine and 3-phenylpropionylglycine. N. Engl. J. Med. 319(20), 1308-1313 (1988).