CHEMISTRY
Joel Miller
Thanh N. Truong
Peter J. Stang
MATHEMATICS
Graeme W. Milton
Jim Carlson
PHYSICS
Charles Jui
Charles Jui
Craig Taylor
Valy Vardeny
Valy Vardeny
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Chemical Cop
By Lee Siegel
The Salt Lake Tribune
University of Utah biologist Jim Ehleringer does chemical detective work -- he helps the federal government track the sources of illegal drugs and counterfeit money. The
method he uses also might be used to trace terrorists' explosives.
It isn't all cops and robbers. Ehleringer's method also can find adulterants like corn syrup in cheap beer, liquor, honey, jams and jellies. One of his students will use the technique
to study why Anasazi Indians vanished from the Southwest 700 years ago.
Ehleringer outlined his research Wednesday during a Science at Breakfast lecture sponsored by the university's College of Science.
His chemical analysis method is so effective in pinpointing where cocaine and heroin come from that the federal Drug Enforcement Administration (DEA) will start using it
this summer at its laboratory in McLean, Va. Some 6,000 drug samples a year will be analyzed.
"This is a major advance in determining the source of illicit drugs," said Bob Klein, research supervisor at the DEA lab. "It will dramatically help the U.S. government in allocating resources to combat drug trafficking."
Ehleringer weighs the atoms in chemicals with a mass spectrometer. A chemical element has different forms of atoms called isotopes, which are identical chemically but have
slightly different atomic weights. Using the mass spectrometer, Ehleringer measures the ratios of various non-radioactive isotopes in drugs, currency paper, explosives, foods and
water to learn where those substances originated.
To analyze cocaine, the ratio of rare nitrogen-15 to common nitrogen-14 reveals the type of soil in which the coca plant was grown, and ultimately the location of that soil. In
addition, leaf pores open wider on coca plants in humid environments, so they absorb more carbon dioxide than plants in drier environments. The plants have an enzyme that
discriminates against rare carbon-13 isotopes. So, as plants in humid environments take in more carbon dioxide, they develop a lower ratio of carbon-13 to common carbon-12 than
plants in drier environments.
Ehleringer's technique is so precise in detecting slight humidity differences that it can distinguish whether cocaine is produced in Colombia, Peru, Ecuador or Bolivia.
Heroin is made when morphine from opium poppies is combined with acetic anhydride. That chemical and morphine both contain carbon. Analysis of carbon-13/carbon-12
ratios in heroin tells Ehleringer where the poppies were grown, based on varying humidities in Southeast Asia, Southwest Asia, South America and Mexico. It also helps him
determine where the morphine was processed into heroin, since acetic anhydride has carbon isotope ratios that vary depending on where it was made.
The DEA previously used impurities to determine how a drug was processed, and thus get some idea of where. Klein said Ehleringer's method is 95 percent accurate in
determining where a drug was grown or processed, allowing DEA to target its anti-drug efforts.
"If 60 percent of the heroin in this country is derived from South America, then we're not going to put 90 percent of our resources into the Golden Triangle -- Burma, Thailand
and China," Klein said.
Ehleringer now is working with a federal task force that wants to use isotopes to trace raw materials and manufacturing methods for gunpowder and explosives, particularly in
terrorists' bombs.
"If you have a bomb, one might be able to identify where that material originated from," he said.
In the mid-1990s, he helped the Secret Service track high-quality counterfeit $100 bills. That was possible because cotton in currency paper is grown with water, and "the rain
water in Bogota is different than rain in Berlin, which is different than rain in Salt Lake City," he said.
Water contains hydrogen and oxygen, so Ehleringer analyzes isotopes of those elements in real and counterfeit bills. None of the counterfeits had isotope ratios consistent with
the Texas cotton used in real U.S. bills. Ehleringer's analysis showed early counterfeit $100s came from a colder, wetter climate consistent with eastern Europe. Newer counterfeits
contained cotton from a warmer, drier climate consistent with the Middle East.
Ehleringer said his analysis helped confirm suspicions the counterfeiters were associated with terrorist groups moving from country to country.
Analysis of oxygen isotopes from rain also will be used by Ehleringer and postdoctoral researcher Julia Verville in studying why the Anasazi Indians vanished from the Four
Corners about A.D. 1300.
"Many reasons have been proposed -- disease, war, overuse of farmland," Ehleringer said. "We are proposing it was summer drought, not any kind of drought, which caused
them to leave. They lost summer rains and couldn't grow corn."
Warm summer rain contains more heavy oxygen-18 than winter rain or snowmelt. Verville will examine annual growth rings in trees from the years before the Anasazi vanished.
If the summer-growth portion of those rings has low levels of oxygen-18, that would indicate the trees grew in summer not because of summer rains, but because of groundwater.
Verville also will analyze ancient corn cobs from Anasazi sites to confirm suspicions they did not irrigate crops in the summer.
Ehleringer said the U.S. Customs Service uses isotope analysis to detect corn syrup added illegally to imported honey. Detection of corn syrup is based on the fact there are two
categories of plants in terms of how they consume carbon dioxide.
Warm-season grasses and corn, sorghum and millet take up more carbon-13 from carbon dioxide, while trees, soy, rice and cool-season grasses consume little. When jams and
jellies have carbon isotope ratios that resemble plants such as corn rather than that of fruit trees, "it means you are buying corn syrup," Ehleringer said.
Alcohol in real beer comes from fermentation of grains such as barley. Cheaper beers and whiskeys use corn syrup to make the alcohol, Ehleringer said.
Ehleringer studied carbon isotope ratios in 100 domestic beer brands. One-third of the beers -- including those made by Utah microbreweries -- were authentic, containing alcohol
only from barley or wheat. The other two-thirds, mostly cheaper brands, used one part barley and one part corn syrup as the source of alcohol.
"You get what you pay for," said Ehleringer.
Originally published January 27, 2000, in The Salt Lake Tribune.
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