A residue analytical method to extract a pesticide from corn pollen was provided by a client. The goal of this project was to use the provided method as a guideline to measure pesticide residues in corn pollen collected at field trials. The pesticide was applied in-furrow to soil at two different rates at planting and was applied as a seed coating at two different rates at three field sites. At pollen shedding (when the plants were at the R1-silking stage), pollen from the corn tassels was collected by hand and transported to the analytical laboratory. Method development was conducted on bee pollen purchased from a local grocer and homogenized using an IKA tube mill. The client provided extraction method involved extracting ~200 mg of pollen with methanol, cleaning the extract with Chem Elut SPE cartridges, followed by an additional clean-up with Mega Bond Elute SI SPE cartridges, and analysis by LC-MS/MS. Initial attempts following the method as written resulted in poor extraction recoveries. After several experiments, it was determined that replacing the two suggested SPE procedures with an HLB prime SPE cartridge to clean the extract resulted in acceptable recoveries. Additionally, the LC gradient was altered from what was provided to provide more of a wash to the column between each sample injection. The method was validated at two concentrations and 27 field samples were successfully processed.

Method development and optimization for extracting a pesticide from bee and corn pollen

2019 Fall National Meeting

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