Use of Food Dyes as Tracers to Measure Multiple Spray Deposits by Ultraviolet-Visible Absorption Spectrophotometry
The food dyes Tartrazine, Indigo Carmine, and Patent Blue were used as tracers to compare the deposition caused by three sequential spray applications on the same collector through multicomponent analysis of the mixture by ultraviolet-visible absorption spectrophotometry. This methodology is quick, easy, economical, and poses no health risks, given the use of authorized food dyes. The errors made in the estimation of the dyes were less than 10% for all the mixtures analyzed when Tartrazine was present in a concentration higher than 1 mg L -1 . The methodology has been used to quantify mixtures of the three dyes on artificial collectors (filter-paper strips) and on leaves of tomato plants. The variability of the data corresponding to the recovery rates of the dyes on the filter paper and leaves was 1.78% and 1.27%, respectively. These values are adequate to compare different spray applications using Tartrazine, Indigo Carmine, and Patent Blue as tracers over the same collector.