Assessment of fluorescent dye Brilliant Sulfaflavine on stainless steel screens as spray collectors

Authors: You, Kyusuk; Zhu, Heping; Abbott, Johnpaul

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2019
Publication Date: 4/30/2019
Publication URL: https://handle.nal.usda.gov/10113/6555356
Citation: You, K., Zhu, H., Abbott, J.R. 2019. Assessment of fluorescent dye Brilliant Sulfaflavine on stainless steel screens as spray collectors. Transactions of the ASABE. 62(2):495-503. https://doi.org/10.13031/trans.13136.
DOI: https://doi.org/10.13031/trans.13136

Interpretive Summary: Fluorescent dyes and artificial collectors have been widely used to determine spray deposition quality of agricultural pesticides and fertilizers in the target field. In order to accurately quantify spray deposition, sprayed dyes must be recovered from the collectors completely, and the fluorescence of applied dye solutions and collectors must be stable in variable experimental environments. In this research, a nontoxic fluorescent dye was investigated as a simulated pesticide, and plastic plate, nylon screen and stainless steel screens were used to simulate leaves. Static and dynamic droplet deposition processes on the collectors were examined using a fluorimeter and a high speed video camera. Dye residues on each collector were inspected through ten continuous reprocessing cycles of fluorescence assessments and digital image analyses. Photo-degradation stability of fluorescence on these collectors was also examined under sunlight. Test results demonstrated that photo-degradation of the dye was insignificant for all collectors while the stainless steel screens outperformed nylon screens and plastic plates in collecting dyed droplets. Thus, stainless steel screens and the fluorescent dye could be safely used for quantification of spray deposition to improve pesticide application accuracy and reduce pesticide waste.

Technical Abstract: The commonly used fluorescent dye, Brilliant Sulfaflavine (BSF, CAS# 2391-30-2), was investigated to determine its photo-stability and recovery on five spray deposition collectors: white plastic plate, nylon screen, and stainless steel (SS) screens with three different meshes (40, 60, 80 meshes). The photo-stability of the deposited dye was determined by measuring the variance of fluorescent intensity under daylight exposure. The recovery rates were investigated with statically dispensed droplets and dynamically discharged droplets. In addition, droplet penetration through screen collectors and the amount of unrecovered dye on used reprocessed collectors were assessed to better understand the differences in dye recover rates among different collector types. Photo-degradation tests verified that all collector materials were insignificant to fluorescence degradation (less than 3.1 %) during 120 minutes of solar exposure showing less than 3.1 % of degradation. Nylon screens had the lowest recovery rate for statically dispensed droplets at 87.0%, whereas plastic plates and stainless steel screens recovered more than 90% of deposited dye. For the dynamically discharged droplets, the 60- and 80-mesh SS screens recovered over 70% of deposited dye whereas nylon screens showed lower than 50% recovery rate over five replications. These results were substantiated visually by the high speed imaging system that detected droplets penetrating more frequently through larger open-sized mesh collectors. Throughout ten continuous reprocessing cycles of the fluorimetry test, the fluorescent intensity on reprocessed nylon and 80-mesh SS screen collectors increased by 16.8% and 12.7%, respectively, while there was less than a 1% change in fluorescent intensity on the 40- and 60-mesh SS screens over the repetitions. These results were clarified through the dye residual verification using digital image analyses.