Degradation of Fluorescent Tracer Dyes Used in Spray Applications

Fluorescent dyes Basonyl Red 485, Eosine OJ, and Tinopal CBS-X were used to study the effect of solar radiation on dye degradation. Drops of dye solutions, prepared at 10, 100, and 1000 mg/L concentrations, were dispensed on mylar plastic and cellulose filter paper targets. Dye deposits, made with 1, 2, and 4 μL drops, were exposed to 5–120 min sunlight (0.125–3.963 MJ/m² solar radiation). The deposits were washed with deionized water and the amount of fluorescence was determined with a fluorometer.

All three dyes showed considerable degradation under solar radiation and the effects of both dye concentration and target type were significant. Degradation was higher at lower concentrations. Basonyl deposits had higher degradation on mylar sheet while Eosine and Tinopal (except 10 mg/L) deposits showed more degradation on filter paper. Drop size did not have a significant effect on dye degradation.