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.