Evaluation of a rhodamine-WT dye/glycerin mixture as a tracer for testing direct injection systems for agricultural sprayers

Authors

Joe D. Luck, University of Nebraska-LincolnFollow
Scott A. Shearer, Ohio State University, Columbus, OhioFollow
Brian D. Luck, Mississippi State University, Starkville, Mississippi
Fred A. Payne, University of Kentucky, Lexington, Kentucky

Document Type

Article

Date of this Version

2012

Citation

Applied Engineering in Agriculture Vol. 28(5): 643-646

Comments

© 2012 American Society of Agricultural and Biological Engineers

Abstract

The purpose of this study was to provide valuable insight regarding the use of Rhodamine WT (red) dye as a tracer for evaluating injected concentrations. More specifically, the effects of mixing the dye with glycerin to simulate the viscosity of a pesticide (e.g., glyphosate) or injecting the dye/glycerin mixture into deionized (DI) versus tap water on developing appropriate calibration equations were evaluated. Test results indicated that mixing the dye in a solution of glycerin and DI water significantly affected absorbance measurements compared to the dye mixed solely in DI water. The error in estimating absorbance was 7.4% between the two calibration equations. Therefore, any calibration curves must include a solution containing glycerin to compensate for this. Absorbance results also indicated that potable tap water

could be used to simulate the spray carrier as opposed to the DI water. A calibration curve was developed for the simulated pesticide (dye/glycerin/DI water solution) injected into the carrier (tap water) for solutions ranging from 2,000:1 (carrier:pesticide) to 500,000:1; an overall dilution range of 250:1. This dilution range exceeded typical pesticide tank-mixed dilutions which were on the order of 11:1 for the application of glyphosate for corn or soybeans. The regression model standard error for predicting the dye concentration based on absorbance measurements was 5.3x10^-6.