Field-Portable Pesticide Residue Analyzer

NON-TECHNICAL SUMMARY: Modern agriculture depends on pesticides to curb infestations and increase crop yield and to produce the quantity and quality of food demanded by today\'s society. However, many pesticides kill insects by attack of the central nervous system, and use of excessive concentrations pose a threat to human health. The EPA Office of Pesticide Programs is charged with setting tolerance levels (generally from 0.01 to 10 part-per-million concentrations) for food and feed, while the FDA and USDA are charged with enforcing tolerances. In 2002 (most recent compiled data) 3.2% and 5.4% of the imported fruit and vegetables tested, respectively, exceeded USA tolerance levels (domestic values: 0.7% and 0.8%). The amount of contaminated fruit, more than 1 million tons, takes on added concern, since a significant portion of the fruit imports are used in baby food. Furthermore, no more than 1% of the food was tested. It is literally impossible for inspectors to analyze the huge volume of imported food, considering that current laboratory procedures take more than an hour per sample. The purpose of this program is to develop a simple-to-use, field-portable analyzer to inspect food and feed for pesticide residues accurately and rapidly. The proposed analyzer will allow inspectors to identify and quantify pesticide residue concentrations in minutes to ensure compliance and decrease the distribution of unsafe food. <P>

APPROACH: The overall approach of this program is to develop a method and analyzer that uses surface-enhanced Raman spectroscopy (SERS) to detect, identify, and quantify pesticides. The Phase I program will focus on developing four different chemically-selective SERS-active capillaries that provide maximum sensitivity for a number of pesticides. This will be achieved in the following two comprehensive tasks. The first task will determine which SERS-active sol-gel yields the best sensitivity for the selected pesticides. This will be accomplished by measuring the SERS spectra of carbaryl, chlorpyrifos-methyl, endosulfan and its primary metabolite endosulfan sulfate, fonofos, malathion, phosmet, pirimiphos-methyl, and thiabendazole with a target sensitivity of 10 ppb. The second task will determine the amount of sample preparation required to discriminatively detect and quantify pesticide residues in fruits and vegetables using SERS-active capillaries. This will be accomplished by analyzing samples with and without \"spiked\" pesticides by SERS during each step of a procedure designed to extract, isolate, and detect pesticide residues in fruits and vegetables.