EVALUATION OF 5 FLUORESCENT DYES AND TRIETHYL PHOSPHATE AS ATMOSPHERIC TRACERS OF AGRICULTURAL SPRAYS

The photostability of five commonly used fluorescent dyes and an organ ophosphate, triethyl phosphate, was compared on microscope slides or i n glass beakers after exposure to sunlight outdoors. Our goal was to d etermine which chemicals would be most suited for use as tracers for t he simulation of long distance transport of herbicides in the atmosphe re and as dual tracers for a dual sprayer system for the evaluation of the effects of adjuvants on spray drift potential of agricultural spr ays. The dyes and triethyl phosphate were analyzed with a fluorescent spectrometer and a GC (NPD), respectively. Half lives were estimated t o be approximately 7 minutes for Tinopal and Eosine, 15 minutes for Fi uorescein, 0.75 similar to 3 hours for Rhodamine B (RhB) and 0.5 hour for triethyl phosphate. Brilliant sulfaflavine (BSF) was the most pers istent chemical, degrading only 11.3% after 8 hours of exposure to sun light. BSF was selected as the best tracer of those tested, to simulat e long distance atmospheric transport of herbicides based on its long persistence. RhB and BSF were selected as the best products for use as dual tracers for a dual sprayer system based on similar persistence o ver the first hour of exposure to sunlight.