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New Method Speeds Up Pesticide Residue Monitoring

By Jim Core
July 2, 2003

A new approach to analyzing diverse pesticide residues in fruits and vegetables makes it easier and less expensive for analytical chemists to do their jobs.

QuEChERS (pronounced catchers), developed by the Agricultural Research Service, stands for "quick, easy, cheap, effective, rugged and safe." It's a streamlined approach for extracting pesticide residues from food samples and preparing them for analysis.

Steven J. Lehotay, a research chemist with ARS' Eastern Regional Research Center, Wyndmoor, Pa., developed the QuEChERS method with Michelangelo Anastassiades, a visiting scientist from a government laboratory in Stuttgart, Germany.

Current methods are time-consuming, expensive and labor-intensive. Therefore, monitoring rates are low, and laboratory costs are high.

According to the U.S. Food and Drug Administration, more than half of the samples of produce tested in the United States typically do not have measurable residues. Less than one percent of tested samples exceed the maximum amount of a given pesticide or its breakdown products allowed to remain in or on food commodities. Washing, peeling or cooking most produce can help remove most residues.

Using QuEChERS, a single chemist can now prepare a batch of 10 previously chopped samples in about 30 minutes with $1 of materials per sample. This translates to at least 4-fold lower material costs than traditional methods. According to Lehotay, the method also combines different steps, which reduces the chance for errors.

A single, easy-to-clean Teflon tube is the only item to be washed and reused, eliminating all of the glassware used in conventional methods. Less than 10 milliliters of solvent waste is generated, much less than the 75-450 milliliters generated by other methods. One key to the new approach is the development of a rapid procedure, called "dispersive solid-phase extraction," to quickly remove interfering nontarget compounds and residual water.

Read more about this research in the July issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.