Abstract
Abstract Fluorescent tracer dyes are popularly used in agricultural spray application studies to evaluate on-target canopy deposition and off-target drift, and the methods/instruments used for evaluating dye deposit must assure reliability of the data generated. A laboratory setup was configured to adapt a submersible fluorometer for controlled and reliable measurement of pyranine dye fluorescence in liquid samples. The system setup was blanked using a clean sample of de-ionized water and calibrated using standard dye solutions of known concentration (100 to 1,000,000 parts per trillion [ppt]) made from two dyes of different levels of purity (pyranine 98 % and pyranine 85 %). Pyranine 85 % fluorescence readings were consistently lower with reduction factor averaging ∼0.62 times that of pyranine 98 % within a range from 500 to 1,000,000 ppt. The results were verified using a standard laboratory fluorometer. Spray deposition assessment of string, plastic card, cotton ribbon, and artificial foliage samplers was accomplished using the configured fluorometer system setup. The results showed no significant difference among dye purity levels (P = 0.430), no statistically significant interaction between dye purity and concentration (P = 0.484), and no statistically significant interaction between dye purity and sampler type (P = 0.173). Consequently, the configured setup can produce measurements with similar quality as the standard laboratory fluorometer and both dyes tested may be equally used for spray deposition and drift assessments, or for similar applications.
Published Version
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