Grapefruit mercaptan

Pure grapefruit mercaptan, or citrus-derived oils rich in grapefruit mercaptan, are sometimes used in perfumery and the flavor industry to impart citrus aromas and flavors. However, both industries actively seek substitutes for grapefruit mercaptans for use as a grapefruit flavorant, since its decomposition products are often highly disagreeable to the human sense of smell.

The detection threshold for the (+)-(R) enantiomer of grapefruit mercaptan is 2×10⁻⁵ ppb, or equivalently a concentration of 2×10⁻¹⁴. This corresponds to being able to detect 2×10⁻⁵ mg in one metric ton of water - one of the lowest detection thresholds ever recorded for a naturally occurring compound.