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ORCID

https://orcid.org/0009-0007-3628-9271

Access Type

Open Access Thesis

Document Type

thesis

Degree Program

Molecular & Cellular Biology

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2024

Month Degree Awarded

February

Abstract

Adjuvants can enhance the performance of the pesticide active ingredients in many ways including decreasing surface tension and reducing evaporation. Understanding how adjuvants effect pesticide behavior (e.g., surface persistence) is crucial for developing effective pesticide formulations, as well as facilitating the development of effective approaches to reduce pesticide residues from the surface of fresh produce post-harvest. The objective of this study is to investigate the effect of a non-ionic surfactant, Surf-Ac 910, on the persistence of two model pesticides, thiabendazole and phosmet on apple surfaces. The result shows that the addition of Surf-Ac 910 increased both the maximum wetted area and evaporation rate of thiabendazole, a systemic pesticide, and phosmet, a non-systemic pesticide. Utilizing surface-enhanced Raman spectroscopy to explore the surface and penetrative behaviors of thiabendazole and phosmet revealed that the addition of Surf-Ac 910 influenced the Raman signal of pesticides as well. The addition of Surf-Ac 910 decreased the Raman signal intensity when added to phosmet but did not affect the Raman signal intensity when added to thiabendazole. In terms of penetration, the addition of Surf-Ac 910 did not affect the penetration depth of phosmet but slightly increased the penetration depth of thiabendazole. These findings were true for both short-term, 40 minutes, and long-term, 3 days, exposure. Next, the effects of adjuvants on the removal of pesticide residues were investigated. Common household materials, such as baking soda, were effective at removing surface pesticide residues. After testing a variety of baking soda concentrations and starch granules, 2% baking soda and 2% corn starch were found to be the most effective baking soda concentration and starch granule respectively. 2% corn starch was the most effective removal method overall, with 99% of pesticide with/without adjuvant removed in just 5 minutes of wash time. Overall, this study demonstrated that although adjuvant Surf-Ac 910 could affect the surface persistence of pesticides, washing with common household materials such as 2% corn starch can be used as an effective, safe, and economic way to reduce pesticide exposure through fresh produce.

DOI

https://doi.org/10.7275/36371794

First Advisor

Lili He

Second Advisor

John Gibbons

Third Advisor

Matthew Moore

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