Subject: Pesticide Residue Analysis
Application: DNA/RNA and Other Extractions
The high-throughput analysis of pesticides has been hindered by the slow and laborious sample preparation stage. Using traditional clean-up procedures, over twenty steps are required to get the sample in a convenient form for analysis, which limits sample throughput to typically 8 samples per day. This study evaluates a new approach using an innovative laboratory tissue homogenizer, to extract various pesticide residues from different kinds of plant materials and to identify and quantitate the active ingredients by LC/MS/MS. It shows that by automating the sample preparation procedure, the number of clean-up steps can be significantly reduced, resulting in an increased sample throughput over traditional approaches.
Three of the leading pesticides sold by DuPont are Famoxate®, Curzate® and Tanos® to control various fungal diseases in crops. Famoxate is a fungicide containing the active ingredient famoxadone and is mainly used to control early blight tomatoes. It protects from spore germination and fungal growth by its strong adhesion to leaf and stem surfaces. Curzate is a fungicide that contains cymoxanil as the active ingredient and is mainly used for late blight potatoes, but is also applied to grapes, tomatoes, cucumbers and leafy vegetables. Its protection mechanism is to penetrate the surface to induce host defense response to stop lesion growth and sporulation. Tanos is a fungicide containing both famoxadone and cymoxanil and the cumulative effect of these two active ingredients offers even better control of late blight potatoes. The typical pesticide residue set at DuPont contains 8 samples and usually takes an 8 hour workday to complete. The goal of this study was to take advantage of recent developments in sample preparation with the Geno/Grinder® and instrument sensitivity and selectivity using the API 5000 LC/MS/MS system to increase the number of samples analyzed per day by a factor of three. The methodology follows OPPTS 860-1360 Multiresidue Test Method(1), which has been developed by the United States Environmental Protection Agency (USEPA) Office of Prevention, Pesticides and Toxic Substances (OPPTS), for use in the testing of pesticides and toxic substances. Under this method, test data must be submitted to the agency for review under federal regulations and dictates that average recoveries have to be 70-120% with a coefficient of variation (CV) or RSD of less than 15%.
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