Six gallons of gamma-butyrolactone (GBL) were found in air cargo coming from France.
Officials say the chemical arrived in liquid form in two separate shipments. Both were being sent to an address in Hillsborough County, Florida.
GBL is often used by predators, authorities say, as part of a date rape drug. It's also commonly used by bodybuilders to increase growth hormones.
According to the DEA, GBL is a chemical analog of gamma-hydroxybutyric acid (GHB), a highly addictive central nervous system depressant that can potentially cause respiratory distress, comas, or death.
Used properly, GBL is an industrial solvent that strips paint and rust.
"Customs and Border Protection (CBP) will continue to use our border security authority to search suspect international parcels and intercept dangerous products that could seriously harm American citizens," said Rene Ortega, the acting area port director for CBP's Area Port of Philadelphia. "This is a mission and responsibility that we take very seriously."
No arrests have been made yet in this case.
For more information on the CBP, visit its website here.