Comparative Study of Glyphosate and AMPA Determination in Environmental Samples by Two Green Methods

Bruno Molero Da Silva,Maria Olímpia Oliveira Rezende,Fernanda Benetti

doi:10.4236/oalib.1101553

Bruno Molero Da Silva, Maria Olímpia Oliveira Rezende + Show 1 more

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https://doi.org/10.4236/oalib.1101553

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Abstract

Glyphosate, N-phosphonomethyl-glycine (GLY), is a systemic post-emergence herbicide that controls weeds with great efficiency whose low cost is reflected in its wide application. In the environment, the presence of aminomethylphosphonic acid (AMPA), its main degradation product, is indicative of the application of GLY to the land. The aim of this study was to develop two analytical methods for the determination of GLY by HPLC-UV and GLY and AMPA by GC-MS, in water, soil and sediment samples. The proposed HPLC-UV method proved to be an efficient way of determining GLY in environmental samples of water, soil and sediment, eliminating the step of extraction and clean-up. On the other hand, the GC-MS method can be used to determine both GLY and AMPA simultaneously. The limits of detection (LOD) and quantitation (LOQ) for GLY by the HPLC method were 9.93 and 30.1 μg·L﹣1 for water samples, and 0.040 and 0.120 mg·kg﹣1 for soil and sediment samples, respectively. By the GC-MS method, the LOD and LOQ for GLY were 0.67 and 2.02 μg·L﹣1 for water samples, and 0.0027 and 0.0081 mg·kg﹣1 for soil and sediment samples, respectively. For AMPA, these limits were 0.15 and 0.45 μg·L﹣1 for water samples and 0.0006 and 0.0018 mg·kg﹣1 for soil and sediment samples, respectively. The recoveries ranged from 70% to 120% for water, soil and sediment samples.

Highlights

Glyphosate, N-(phosphonomethyl)-glycine (GLY) is a broad-spectrum systemic post-emergence herbicide which is very efficient in removing invasive plants and shows a low toxicity to those who apply it to the land
It is important to emphasize that the sampling sites in the Monjolinho stream have a high phosphorus concentration, greater than the established limit in Brazilian law [19] for Class 2 waters (0.05 mg∙L−1), which could indicate the presence of fertilizers such as NPK or the discharge of domestic sewage into the stream
The method developed with HPLC-UV is a sensitive and rapid technique to determine glyphosate

Summary

Introduction

Glyphosate, N-(phosphonomethyl)-glycine (GLY) is a broad-spectrum systemic post-emergence herbicide which is very efficient in removing invasive plants and shows a low toxicity to those who apply it to the land. GLY is currently the most widely used herbicide in the world, representing about 60% of all marketed non-selective herbicides [1]. It is relatively inexpensive and highly effective in agriculture, its widespread use. When applied to the soil, part of the herbicide may be washed off or leached, reaching aquatic environments. The possibility of environmental contamination with this molecule should be monitored carefully. The commercial formulation contains a surfactant that irritates the skin [2].

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