Class
Article
College
College of Science
Presentation Type
Oral Presentation
Abstract
Many commercial pesticides fall into the category of semivolatile organic compounds (SOCs). SOCs can either volatilize into the air or deposit onto surfaces in the environment, depending on the temperature. One property that allows for a prediction of this behavior is the plant-air partition coefficient (Kplant-air). The Kplant-air describes the SOC's equilibrium that is formed between a plant surface and the air around after it lands on the plant. Differences in temperature, humidity, and the type of leaf due to different surface properties between species influences the Kplant-air. The objective of this study was to measure the Kplant-air values for different pesticides on different leaves with varying temperature and humidity. The leaves of interest are mandarin orange (Citrus reticulata) leaves and alfalfa (Medicago sativa) leaves, while the pesticides of interest are active ingredient chlorpyrifos, lambda-cyhalothrin, and flupyradifurone. Commercially formulated chlorpyrifos are also analyzed to compare its properties to active ingredient chlorpyrifos. To measure the Kplant-air values, a fugacity meter will be used. This pushes gas through a sample chamber containing leaves contaminated with pesticide. As the gas flows over the leaves, the pesticide on the leaf is in equilibrium between the leaf and the air. As the air and volatilized pesticide exit the sample chamber, it flows through a sorbent trap, which retains the gas-phase pesticide. Pressurized Liquid Extraction (PLE) will then be used to separate the pesticides from the sorbent trap and leaves. Once separated, the pesticides will be analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The ratio of the concentration of the pesticide on the plant to the concentration in the air is the Kplant-air. The Kplant-air values measured in this work will be employed into a previously developed model to allow for more accurate predictions of pesticide fate after it lands on leaf surfaces.
Start Date
4-9-2020 12:00 PM
End Date
4-9-2020 1:00 PM
Plant-Air Partitioning of Semivolatile Pesticides on Citrus and Alfalfa Leaves with Varied Temperature and Relative Humidity
Many commercial pesticides fall into the category of semivolatile organic compounds (SOCs). SOCs can either volatilize into the air or deposit onto surfaces in the environment, depending on the temperature. One property that allows for a prediction of this behavior is the plant-air partition coefficient (Kplant-air). The Kplant-air describes the SOC's equilibrium that is formed between a plant surface and the air around after it lands on the plant. Differences in temperature, humidity, and the type of leaf due to different surface properties between species influences the Kplant-air. The objective of this study was to measure the Kplant-air values for different pesticides on different leaves with varying temperature and humidity. The leaves of interest are mandarin orange (Citrus reticulata) leaves and alfalfa (Medicago sativa) leaves, while the pesticides of interest are active ingredient chlorpyrifos, lambda-cyhalothrin, and flupyradifurone. Commercially formulated chlorpyrifos are also analyzed to compare its properties to active ingredient chlorpyrifos. To measure the Kplant-air values, a fugacity meter will be used. This pushes gas through a sample chamber containing leaves contaminated with pesticide. As the gas flows over the leaves, the pesticide on the leaf is in equilibrium between the leaf and the air. As the air and volatilized pesticide exit the sample chamber, it flows through a sorbent trap, which retains the gas-phase pesticide. Pressurized Liquid Extraction (PLE) will then be used to separate the pesticides from the sorbent trap and leaves. Once separated, the pesticides will be analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The ratio of the concentration of the pesticide on the plant to the concentration in the air is the Kplant-air. The Kplant-air values measured in this work will be employed into a previously developed model to allow for more accurate predictions of pesticide fate after it lands on leaf surfaces.