The Mississippi State Chemical Laboratory (MSCL) routinely analyzes drift complaint samples in the spring. Most of these complaints consist of injured ornamentals or soybeans exposed to the following herbicides: 2,4-D, atrazine, acetochlor, dicamba, glyphosate, and paraquat. The lab currently uses sensitive liquid chromatographic techniques including LC-MS/MS to identify these compounds at residue levels. However, this sensitive method cannot differentiate between the acid, amine, ester, or choline formulations of 2,4-D and dicamba. Therefore, it is imperative new analytical methods are developed to ensure an effective stewardship program. We have begun to investigate the use of Fourier transform infrared spectroscopy (FT-IR) and preliminary data looks promising. Research was conducted in 2017 and 2018 in Starkville, MS using chemometrics coupled to FT-IR to produce classification models capable of identifying specific 2,4-D and Dicamba formulations present in damaged crop tissue. 2,4-D acid (ACID), dimethylamine salt (DMA), choline salt (CHOLINE), and isooctyl ester (ESTER) were applied to susceptible cotton and soybeans at 33, 17, 8, 4, 2, and 1 g 2,4-D ae ha-1. Dicamba diglycolamine (DGA), dimethylamine (DMA), N,N-Bis-(3-Aminopropyl) methylamine (BAPMA), and diglycolamine with potassium acetate (DGAKAC) were applied to susceptible cotton and soybeans at 35, 17.5, 8.75, 4.375, 2.1875, and 1.09375 g dicamba ae ha-1. Samples were homogenized; infrared spectroscopy spectra were generated, and then analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA). Joint PCA-LDA models were only capable of classifying 2,4-D and dicamba formulations in damaged tissue with up to 36% and 40% accuracy, whereas LDA alone produced models with 77 to 80% and 80 to 85% accuracy respectively. This research suggests that with further refining, chemometric analysis of spectral data from damaged crop tissue may be an economical, efficient, and promising application to support management of crop injury cases following off target movement.

Application of FTIR spectroscopy and chemometrics for the classification of auxin herbicides in damaged cotton and soybean tissue

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.