New Apparatus Should Help Farmers Detect Herbicides

A new device called a biosensor will help farmers and regulators detect herbicides and pesticides in soil and water. The biosensor relies on living organisms or their by-products to identify traces of chemical residues in only minutes.

Molecular biologist Autar K. Mattoo at the Agricultural Research Serviceco-developed the biosensor with scientists from the Czech Republic and Italy through a grant supported by the North American Treaty Organization. In Beltsville, Md., Mattoo leads the Vegetable Laboratory of the ARS, the chief research agency of the U. S. Department of Agriculture.

Heavy applications of herbicides and pesticides can leave environmentally unsafe residues in soil and water.

The biosensor detects these residues by using a chlorophyll-protein complex that measures oxygen levels. To use the biosensor, the farmer or regulator passes a soil or water sample through the device. If the sample contains an herbicide, the chemical will react with the biosensor's proteins and inhibit oxygen production. This information is relayed to a computer that displays the data in graph form.

The biosensor can only measure herbicides that inhibit photosynthesis--diuron, atrazine, simazine, ioxynil, bromoxynil and dinoseb. But this group constitutes about 50 percent of all herbicides used in agriculture.

The test is ultra-sensitive. Its detection limits are similar to or slightly better than the more complex, highly sensitive ELISA test, which is antibody-based. The biosensor works well at room or warmer temperatures. Its membrane is stable for up to about 40 hours and can be re-used within that period for any number of measurements.

Once commercialized, it should be economical and easy to use--distinct advantages over currently available herbicide detectors.

A story about the biosensor appears in the November issue of ARS’ Agricultural Research magazine. The story is also on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/nov98/bio1198.htm

Scientific contact: Autar K. Mattoo, ARS Vegetable Laboratory, Beltsville, Md., phone (301) 504-7380, fax (301) 504-5555, amattoo@asrr.arsusda.gov