"The use of these four elements is especially interesting considering that oxygen and hydrogen will provide information related to water source, while the isotopic composition of carbon and nitrogen are related to others factors such as climate, temperature and nutrients availability on the soil," said Elisa Shibuya, a nuclear scientist at the University of Sao Paulo in Brazil.
Shibuya's team did similar analysis on cannabis using just two isotopes.
But while using a variety of isotopes can better pinpoint the drug, scientists need access to drug samples of known origin.
"The availability of these samples by a governmental body for these researchers only becomes possible — whether possible — after overcoming a huge bureaucracy," said Shibuya.
That bureaucracy could ultimately stand in the way of drug enforcement.
"You can't go out and collect your own samples," said Wooller. "There are strict chains of custody to allow the samples to come into our hands."
Wooller is already working closely with the university's police department to obtain the miniscule samples he needs to perform his analysis. And he is also looking for funding to devote a researcher to the project full time. If that happens, a marijuana map could take shape in the next few years, he said.
