June 23rd, 2007
Cataloguing marijuana's fingerprints
When a police officer stops a car and finds marijuana under the driver’s car seat, he has no idea where the marijuana comes from. But as Alaska Report recently wrote, he might be soon able to ask the marijuana itself. Scientists from the Alaska Stable Isotope Facility at the University of Alaska Fairbanks (UAF) are working on an identification system. So far, they can tell if the plants have been grown in Alaska or in Latin America. But they also want to discover if a sample of marijuana confiscated by police officers was grown indoors or out. Their stable-isotope analysis seems to work fine, but they need more marijuana samples from known locations to create a better marijuana database. If you’re growing marijuana in your backyard, you know how to help these researchers…
You can see above a picture of one of these scientists, Matthew Wooller, an Assistant Professor at UAF, using “a spatula to load a sample of benzoic acid into a sample capsule. The facility used benzoic acid as a calibration standard for its instruments.” (Credit: UAF photo by Marmian Grimes) Here is a link to a larger version of this photo. In this 2-minute video by Ty Keltner, Matthew Wooller discusses how marijuana isotopes are analyzed in order to determine the plant’s origin.
Wooller is also the director of the Alaska Stable Isotope Facility where this project is conducted. Here is an introduction to this project: “Marijuana in AK can originate from within the state (e.g. Fairbanks and the Matsu Valley) and from a number of areas outside the state (e.g. Latin America, Canada and the lower 48 states of the U.S.A.). Although Latin America is known to supply a large proportion of the marijuana in the lower 48 states of the U.S.A. the proportions from different potential geographic areas that supply AK are not well known. This is primarily because marijuana confiscated from individuals cannot be traced back to the source from which it was originally grown. We propose developing a forensic method in the Alaska Stable Isotope Facility (ASIF) at the University of Alaska Fairbanks (UAF) for using chemical ‘fingerprints’ (stable isotope compositions) preserved in marijuana samples.”
A recent UAF news release, “Tracing marijuana to its roots,” provides additional details about the process. “The key lies at the atomic level. Of particular interest to Wooller and his colleagues are the stable isotopes of four elements: carbon, oxygen, nitrogen and hydrogen. Isotopes are atoms of elements that have the same number of protons and electrons but different numbers of neutrons. A stable isotope is one that doesn’t decay over time. Those additional or missing neutrons in an isotope slightly alter the mass of the atom, allowing scientists to use a stable isotope ratio mass spectrometer to separate the light isotopes from the heavy ones and form a ratio for each sample. That ratio can tell scientists about the sample and its origins.”
And marijuana, like many other plants, keeps ‘in its memory’ a signature of the environment that it used to be grown in. “For example, oxygen and hydrogen ratios can reveal information about the water a plant used while growing and, as a result, where it was grown. Water in Alaska and other high latitudes generally has a larger proportion of light oxygen and hydrogen stable isotopes than water from locations at lower latitudes. Carbon tells another story, he said. It can offer information on whether a plant was grown outdoors or inside. Nitrogen could provide even more information.”
And as I wrote above, Wooller needs your help. “We need more data,” Wooller said. “We need more analyses of marijuana samples from known locations so we can create these base marijuana isotope maps.”
Sources: Ned Rozell, Alaska Report, May 9, 2007; Marmian Grimes, University of Alaska Fairbanks, June 21, 2007; and various websites
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