Scientist Finds the Secret of Underarm Odor

The smell of success was welcome, but not very sweet, for the scientist who Monday reported that he had finally unlocked the chemical secret of underarm odor.

George Preti of the nonprofit Monell Chemical Senses Center in Philadelphia said he has identified the chemicals in perspiration that are responsible for the smell.

Until Preti’s discovery, chemists had guessed that the distinctive aroma of underarm sweat was caused by hormone-like steroids and isovaleric acid.

But Preti reported at the American Chemical Society’s national meeting that another type of chemical, called methyl-branched hexenoic acid, appears to be the culprit.

The Monell team made the discovery by “using our noses, literally,” Preti said.

Researchers collected large amounts of sweat by having people wear cotton pads under their armpits. The chemical makeup of the resulting extract was then analyzed using a separation technique called gas chromatography.

Instead of just recording each compound with an ordinary detector, the chemists also sniffed the vapors from each compound to figure out which smelled most like typical underarm odor.