Methyl heptadecanoate-d33 is the deuterium labeled Methyl heptadecanoate (HY-W004290). Methyl heptadecanoate (C17:0 methyl ester) is the methyl ester derivative of heptadecanoic acid (HY-W004284). Methyl heptadecanoate is used as an internal standard for quantitative calibration of fatty acids in GC-MS analysis[1][2][3][4].