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

J. D. Luck, S. A. Shearer, B. D. Luck, F. A. Payne

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


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 5.3&;Times;10-6.

Original languageEnglish (US)
Pages (from-to)643-646
Number of pages4
JournalApplied Engineering in Agriculture
Issue number5
StatePublished - 2012


  • Pesticide application
  • Pesticides
  • Precision agriculture
  • Spraying equipment

ASJC Scopus subject areas

  • Engineering(all)


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