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Using Hot Water as a Solvent
To Analyze Atrazine in Meat
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Concerns about food and
environmental quality underscore the need for quick, nontoxic analysis of food
contaminants. That's why Agricultural
Research Service scientists are developing cleaner analytical methods that
use nontoxic solvents and a new technique called subcritical water extraction.
In laboratory studies, ARS postdoctoral research chemist Meredith S.S. Curren
in Peoria, Illinois, is testing subcritical water extraction to remove
potential contaminants from meat samples. Working under the direction of ARS
chemist Jerry W. King at the National Center for Agricultural Utilization
Research, Curren starts with highly purified water and heats it under pressure
to 212 °F. That's as hot as water in a teakettle gets before boiling. Then
she flows the hot, compressed water through a meat sample that's been mixed
with an adsorbent to extract the pesticide residue.
Curren is using subcritical water extraction to remove atrazine from beef
kidney samples. Atrazine is an herbicide widely used to control weeds in
Midwest corn and soybean fields. The tolerance level for atrazine in livestock
meat, fat, and meat byproducts is 20 parts per billion. But this level may
change after the U.S. Environmental Protection Agency reviews atrazine for its
potential as a food and environmental contaminant.
Federal agencies like USDA's Food Safety and Inspection Service need safer
analytical methods like this one to check pesticide levels in foods.
Traditional extraction techniques use toxic organic solvents, which are costly
and unsafe for laboratory workers and the environment. These solvents also
require safe disposal, which adds to the cost of their use. Filtered, purified
water systems, however, are inexpensive and don't require a disposal system.
"Besides being safer for the lab worker, our method is faster than other
analytical techniques," says Curren. She streamlined the technique by
performing extraction and sample cleanup concurrently. Cleanup of lipids and
proteins from the sample is required since the subcritical water extracts other
components in addition to the target pesticide. The total time for analyzing
atrazine in beef kidney with this new method is about 90 minutes. In a single
day, the researchers can analyze a minimum of 20 samples.
The hot-water extraction method can also be used to analyze samples for other
pesticides and antibiotics and their metabolic breakdown products. Use of this
method by food-testing laboratories will ensure that the food we eat continues
to be among the safest in the world.—By
Linda
McGraw, Agricultural Research Service Information Staff.
Meredith S. S. Curren and
Jerry W. King are in the USDA-ARS
New Crops and Processing Technologies Research Unit,
National Center for Agricultural
Utilization Research, Peoria, IL 61604; Curren's phone (309) 681-6236,
King's phone (309) 681-6203, fax (309) 681-6686. |
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"Using Hot Water as a Solvent To Analyze Atrazine
in Meat" was published in the
October 2001
issue of Agricultural Research magazine.
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Last Modified: 02/09/2005
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