Multicommutated Flow System for the Determination of Glyphosate Based on Its Quenching Effect on CdTe-Quantum Dots Fluor
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Multicommutated Flow System for the Determination of Glyphosate Based on Its Quenching Effect on CdTe-Quantum Dots Fluorescence Julia Jiménez-López 1 & Eulogio J. Llorent-Martínez 1 & Pilar Ortega-Barrales 1 & Antonio Ruiz-Medina 1 Received: 9 November 2017 / Accepted: 5 February 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract Glyphosate is the most widely used herbicide at the moment. It presents a broad spectrum of action, hence its use for many different crops. Regulatory agencies have constantly mentioned the low hazard potential to mammals. However, the International Agency for Research on Cancer concluded in 2015 that glyphosate is Bprobably carcinogenic to humans.^ For this reason, it is important to develop reliable analytical methods to study the fate and levels of glyphosate in environmental samples. In this work, we propose a multicommutated flow analysis method for the determination of glyphosate, based on the quenching effect produced by this herbicide on the fluorescence of CdTe quantum dots (λexc/λem 400/548 nm/nm). The proposed analytical method presents detection and quantitation limits of 0.5 and 1.7 μg mL−1, respectively. A sample throughput of 30 samples per hour was achieved using a 2.5 mL min−1 flow rate. Interference studies were carried out to assess the selectivity of the method, observing no interference from other common pesticides. Finally, we carried out recovery experiments in water and cereal samples (amaranth, barley, oat, and quinoa). We obtained recovery yields between 92 and 108% in all the analyzed samples. HPLC-MS/MS was used as reference method to assess the accuracy of the proposed methodology. Keywords Multicommutation . Pesticide . Glyphosate . Cereal . Quantum dots
Introduction Glyphosate, the most widely used herbicide worldwide, was first introduced in the market in 1974, but its practice was somehow limited because it could only be sprayed if the intention was to kill all vegetation (Benbrook 2016). However, the introduction of genetically engineered herbicide-tolerant crops in 1996 considerably increased the applications of this pesticide (Benbrook 2016; Tarazona et al. 2017). Nowadays, glyphosate is used for weed control in agriculture, vegetation control in non-agricultural areas, and harvesting aid as crop desiccant (Tarazona et al. 2017). In some cases, farmers increase glyphosate application rates and spray more often to combat weeds less sensitive to this pesticide. Glyphosate has thus become a concern due to its ubiquitous use in the last few years. Although glyphosate potential toxicity to mammals has
* Antonio Ruiz-Medina [email protected] 1
Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
commonly been described as low, the International Agency for Research on Cancer (IARC) assessed glyphosate as Bprobably carcinogenic to humans (Group 2A)^ in 2015 (IARC 2015). This assessment has generated controversy, as neither the European Un
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