Law-enforcement officials have a new weapon in the hunt for South American growers who cultivate coca plants for cocaine production. Scientists in the United States have devised a method for identifying the hidden chemical stamp of the narcotic's geographical origin.
The research team analyzed 200 sets of coca leaves of known origin provided by the Drug Enforcement Administration (DEA) to determine the signatures for five distinct coca-growing regions in the Andes. With this database, the team pinpointed the origin of their cocaine samples with 96 percent accuracy, as reported in the Nov. 16 Nature. More recently, the researchers used the database to identify additional samples.
The method works because cocaine retains the chemical signa