Choice of Tracers for the Evaluation of Spray Deposits

The objective of the present study was to establish a methodology using tracer substances for the evaluation of the distribution and amount of spray deposits, with the possibility to adjust the surface tension of the spraying solution. The following products were tested: 0.15% Brilliant Blue, 0.15% Saturn Yellow in 0.015% Vixilperse lignosulfonate and 0.005% sodium fluorescein, and mixtures of Brilliant Blue plus Saturn Yellow and Brilliant Blue plus sodium fluorescein at the same concentrations. This permitted the development of a qualitative method based on visual evaluation of the distribution of the pigment under ultraviolet light and of a quantitative method based on the determination of the amount of the dye deposited in the same solution. Moreover spray deposition could be evaluated at different surface tensions of the spraying solution, in order to simulate the effect of agrochemic al formulations.