INTRODUCTION:  Identification of unknowns observed when pesticide products are mixed in application equipment is critical to understanding interactions between multiple actives and products prior to field season. Understanding traditional clean out effectiveness involves low level identification by mutiple chromatographic methodologies. However, when solid unknowns are observed, chromatographic methodologies often fall short in their ability to accurately identify insoluble unknowns. Additional analytical technologies including infrared spectroscopy and scanning electron microscopy can be highly beneficial in identifying unknowns observed in tank mix studies.METHODS:  During a tank mix study, an unknown solid was observed in the filters during the tank clean out procedue. The unknown solid did not dissolve in many of the common solvents used. As a result, the unknown was analyzed by a Bruker Tensor 27 Infared Spectroscopy utilizing an ATR crystal and the Bio-Rad Know-It-All library. After initial results were obtained, the samples were then analyzed using a Leica DM5000B upright microscope and a Hitachi TM-1000 table top SEM.PRELIMINARY DATA: Preliminary results indicated that the ATR-IR spectrum of the unknown was consistent with cellulose. The sample was then analyed using a Leica DM5000B upright microscope and a Hitachi TM-1000 table top SEM. The images from the SEM were consistent with cotton and wood fibers likely resulting from paper. Additionally, the results from the Leica DM5000B upright microscope supported the results obtained from the SEM. Ultimately, the SEM and microscope information was used to prove that the unknown solid was a result of a cap liner from one of the chemicals used during the clean out protocol falling into the tank and contaminating the clean out solution.

Application of IR and scanning electron microscopy to identify an unknown observed in a pesticide application tank mix study

246th National Meeting (2013)

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