Quantitative analysis and correction of temperature effects on fluorescent tracer concentration measurement

Authors: ZHANG, ZHIHONG - Kunming University Of Science And Technology; Zhu, Heping; GULER, HUSEYIN - Ege University

Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2020
Publication Date: 6/2/2020
Citation: Zhang, Z., Zhu, H., Guler, H. 2020. Quantitative analysis and correction of temperature effects on fluorescent tracer concentration measurement. Sustainability. 12(11):4501. https://doi.org/10.3390/su12114501.
DOI: https://doi.org/10.3390/su12114501

Interpretive Summary: Fluorescent tracers have been widely used to simulate pesticides in field tests to evaluate sprayer performances and to quantify spray deposits and drift potentials. This is because fluorescent tracers are relatively highly sensitive, economical, practical and non-poisonous compared to analyses of active ingredients in pesticides. However, there are also concerns on the stability of fluorescence affecting the measurement accuracy due to variations in ambient conditions during experiments. In this research, effects of solution temperatures on concentrations of three popular fluorescent tracers were examined. Test results revealed that the measured tracer concentrations in spray solutions were influenced by the solution temperature and the tracer type. Third-order polynomial correction models were developed to numerically correct the measured concentration errors due to the solution temperature effect. As a result of this research, recommendations were made that spray sample analyses should use the correction models if the analyses must be processed in the field; otherwise, the samples should be calibrated and analyzed in laboratories with the same constant ambient temperature.

Technical Abstract: To ensure an accurate evaluation of pesticide spray application efficiency and pesticide mixture uniformity, reliable and accurate measurements of fluorescence concentrations in spray solutions are critical. The objectives of this research were to examine effects of solution temperature on measured concentrations of fluorescent tracers as the simulated pesticides, and to develop models to correct the deviation of measurements caused by temperature variations. Fluorescent tracers (BSF, Eosin, Fluorescein sodium salt) were selected for tests with the solution temperatures ranging from 10° to 45°C. The results showed that the measured concentrations of BSF decreased as the solution temperature increased, and the decrement rate was high at beginning and then slowed down and tended to become a constant. In contrast, the concentrations of Eosin decreased slowly at beginning and then noticeably increased as temperatures increased. On the other hand, the concentrations of Fluorescein sodium salt had little variations with its solution temperature. To ensure the measurement accuracy, correction models were developed using the response surface methodology to numerically correct the measured concentration errors due to variations with the solution temperature. Corrected concentrations using the models agreed well with the actual concentrations, and overall relative errors were reduced from 42.36% to 2.91% for BSF, 11.72% to 1.55% for Eosin, and 2.68% to 1.17% for Fluorescein sodium salt. Thus, this approach would be used to improve pesticide sprayer performances by accurately quantifying droplet deposits on target crops and off-target areas.