Since Tasmania produces massive amounts of opium straw for the pharmaceutical industry, Australian cops want to know if any of the carefully-regulated crops are making their way onto the black market. To solve that problem, chemists at the University of Newcastle have found an easy way to identify heroin made from the island-grown poppies.

Tasmanian poppies were bred for medicinal rather than recreational use. They contain very little morphine, the precursor to heroin. But they are rich in thebaine, a quite toxic chemical that is used as a starting point to make prescription painkillers. Due to its unique composition, the plant is very valuable to the producers of legitimate medications, and bad news for drug dealers. You could say it’s the bane of junkies (get it?).

Working in cooperation with Jana Skopec at the Australian government analytical laboratories, Luke Odell and Adam McCluskey made a crude batch of heroin from Papaver somniferum Norman, a type of opium poppy that originated on the southern island. They found several chemicals that are not present in heroin from other parts of the world. All together, those molecules make up a chemical fingerprint that can clearly identify a batch of heroin as Tasmanian.

The classic tool of a forensic chemist is a gas-chromatography mass spectrometer. Feed the common instrument a mixture of chemicals and it will separate them out, identifying each of them one by one. McCluskey and his team showed that the homegrown heroin contains relatives of the molecule oripavine. They call those chemicals markers because they make Tasmanian heroin unique. None of them could be found in drugs that were seized in Colombia, Myanmar, Turkey, or Pakistan.