title: MALDI-MS Imaging Analysis of Fungicide Residue Distributions on Wheat Leaf Surfaces.
abstract: Improved retention and distribution of agrochemicals on plant surfaces is an important attribute in the biological activity of pesticide. Although retention of agrochemicals on plants after spray application can be quantified using traditional analytical techniques including LC or GC, the spatial distribution of agrochemicals on the plants surfaces has received little attention. Matrix assisted laser desorption/ionization (MALDI) imaging technology has been widely used to determine the distribution of proteins, peptides and metabolites in different tissue sections, but its application to environmental research has been limited. Herein, we probed the potential utility of MALDI imaging in characterizing the distribution of three commercial fungicides on wheat leaf surfaces. Using this MALDI imaging method, we were able to detect 500 ng of epoxiconazole, azoxystrobin, and pyraclostrobin applied in 1 μL drop on the leaf surfaces using MALDI-MS. Subsequent dilutions of pyraclostrobin revealed that the compound can be chemically imaged on the leaf surfaces at levels as low as 60 ng of total applied in the area of 1 μL droplet. After application of epoxiconazole, azoxystrobin, and pyraclostrobin at a field rate of 100 gai/ha in 200 L water using a track sprayer system, residues of these fungicides on the leaf surfaces were sufficiently visualized. These results suggest that MALDI imaging can be used to monitor spatial distribution of agrochemicals on leaf samples after pesticide application.
authors.affiliation: Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States.
authors.forename: Suresh P
authors.initials: SP
authors.lastname: Annangudi
authors.affiliation: Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States.
authors.forename: Kyung
authors.initials: K
authors.lastname: Myung
authors.affiliation: Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States.
authors.forename: Cruz
authors.initials: C
authors.lastname: Avila Adame
authors.affiliation: Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Gilbert
mesh_terms: D004852:Epoxy Compounds / Q000032:analysis; D005659:Fungicides, Industrial / Q000032:analysis* / Q000737:chemistry; D021621:Imaging, Three-Dimensional; D057230:Limit of Detection; D008689:Methacrylates / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry*; D011743:Pyrimidines / Q000032:analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D000073739:Strobilurins; D014230:Triazoles / Q000032:analysis; D014908:Triticum / Q000737:chemistry*
chemical_list: D004852:Epoxy Compounds; D005659:Fungicides, Industrial; D008689:Methacrylates; D011743:Pyrimidines; D000073739:Strobilurins; D014230:Triazoles; C087670:azoxystrobin; C109476:epoxiconazole