More and enhanced glyphosate analysis is needed

Chromatographic Methods for the Determination of Glyphosate in Cereals Together with a Discussion of Its Occurrence, Accumulation, Fate, Degradation, and Regulatory Status

The European Union's recent decision to renew the authorization for the use of glyphosate until 15 December 2033 has stimulated scientific discussion all around the world regarding its toxicity or otherwise for humans. Glyphosate is a chemical of which millions of tons have been used in the last 50 years worldwide to dry out weeds in cultivated fields and greenhouses and on roadsides. Concern has been raised in many areas about its possible presence in the food chain and its consequent adverse effects on health. Both aspects that argue in favor of toxicity and those that instead may indicate limited toxicity of glyphosate are discussed here. The widespread debate that has been generated requires further investigations and field measurements to understand glyphosate's fate once dispersed in the environment and its concentration in the food chain. Hence, there is a need for validated analytical methods that are available to analysts in the field. In the present review, methods for the analytical determination of glyphosate and its main metabolite, AMPA, are discussed, with a specific focus on chromatographic techniques applied to cereal products. The experimental procedures are explained in detail, including the cleanup, derivatization, and instrumental conditions, to give the laboratories involved enough information to proceed with the implementation of this line of analysis. The prevalent chromatographic methods used are LC-MS/MS, GC-MS/SIM, and GC-MS/MS, but sufficient indications are also given to those laboratories that wish to use the better performing high-resolution MS or the simpler HPLC-FLD, HPLC-UV, GC-NPD, and GC-FPD techniques for screening purposes. The concentrations of glyphosate from the literature measured in wheat, corn, barley, rye, oats, soybean, and cereal-based foods are reported, together with its regulatory status in various parts of the world and its accumulation mechanism. As for its accumulation in cereals, the available data show that glyphosate tends to accumulate more in wholemeal flours than in refined ones, that its concentration in the product strictly depends on the treatment period (the closer it is to the time of harvesting, the higher the concentration), and that in cold climates, the herbicide tends to persist in the soil for a long time.

Validation and Application of UPLC-MS/MS Method to Analysis of Glyphosate and its Metabolites in Water

A method was developed to determine glyphosate and their metabolites in water. The widespread use of this herbicide in agricultural activities worldwide, despite the reported adverse effects on both the environment and health, is a cause for concern and makes it necessary to monitor its presence through a method that guarantees the determination at trace levels. A direct extraction of the analytes with phosphate buffer was performed with subsequent derivatization with 9-fluorenylmethyl chloroformate. The quantification was determined by Ultra Performance Liquid Chromatography-tandem mass spectrometer. The method was validated through the following parameters: selectivity, detection and quantification limits, linearity, accuracy, precision and uncertainty. The average recoveries ranged between 94.08 and 103.31%. Additionally, detection limits from 0.396 to 0.433 μg/L, and the quantification limit was 5.0 μg/L for all the analytes evaluated. In terms of linearity and precision, the results obtained were in the ranges considered adequate (R2 ≥ 0.99 and CV ≤ 20%), the estimated expanded uncertainty was 12.95, 11.15 and 13.83% for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. This method was successfully applied for the determination of the target analytes in irrigation water samples, detecting concentrations of aminomethylphosphonic acid over limit detection for some sampling sites.

Hormesis, the Individual and Combined Phytotoxicity of the Components of Glyphosate-Based Formulations on Algal Growth and Photosynthetic Activity

The occurrence of the market-leading glyphosate active ingredient in surface waters is a globally observed phenomenon. Although co-formulants in pesticide formulations were considered inactive components from the aspects of the required main biological effect of the pesticide, several studies have proven the high individual toxicity of formulating agents, as well as the enhanced combined toxicity of the active ingredients and other components. Since the majority of active ingredients are present in the form of chemical mixtures in our environment, the possible combined toxicity between active ingredients and co-formulants is particularly important. To assess the individual and combined phytotoxicity of the components, glyphosate was tested in the form of pure active ingredient (glyphosate isopropylammonium salt) and herbicide formulations (Roundup Classic and Medallon Premium) formulated with a mixture of polyethoxylated tallow amines (POEA) or alkyl polyglucosides (APG), respectively. The order of acute toxicity was as follows for Roundup Classic: glyphosate < herbicide formulation < POEA. However, the following order was demonstrated for Medallon Premium: herbicide formulation < glyphosate < APG. Increased photosynthetic activity was detected after the exposure to the formulation (1.5-5.8 mg glyphosate/L and 0.5-2.2 mg POEA/L) and its components individually (glyphosate: 13-27.2 mg/L, POEA: 0.6-4.8 mg/L), which indicates hormetic effects. However, decreased photosynthetic activity was detected at higher concentrations of POEA (19.2 mg/L) and Roundup Classic (11.6-50.6 mg glyphosate/L). Differences were demonstrated in the sensitivity of the selected algae species and, in addition to the individual and combined toxicity of the components presented in the glyphosate-based herbicides. Both of the observed inhibitory and stimulating effects can adversely affect the aquatic ecosystems and water quality of surface waters.

Synthesis and application of purine-based fluorescence probe for continuous recognition of Cu2+ and glyphosate

In this study, a novel fluorescent sensor, N,N-dimethyl-4-((2-(8-m-ethyl-9-(naphthalen-1-yl)-9H-purin-6-yl)hydrazineylidene)methyl)aniline(PHA), which was constructed via Schiff base reaction of purine derivatives and dimethylaminobenzaldehyde. This probe showed significant selective fluorescence quenching of Cu2+, and accompanying with an increase in Cu2+ concentration and a change in solution color from colorless to yellow. The outstanding features of PHA include low detection limit (0.429 μM), strong anti-interference ability and fast response time. We further investigated the chelation mechanism of PHA and Cu2+ by Job's plot experiment, density generalization theory (DFT), and the probe PHA can form a 1:2 complex with Cu2+ ions, leading to a fluorescence quenching process, thus realizing the rapid detection of Cu2+. In addition, this new fluorescent sensor [PHA-Cu2+] can be used to detect pesticide residues in solution. When the [PHA-Cu2+] system was mixed with glyphosate solution, that a fluorescence recovering was observed. This may be because glyphosate chelates more strongly with Cu2+ ions, making the copper ions dissociated from the [PHA-Cu2+] system. The detection limit of the fluorescent sensor [PHA-Cu2+] for glyphosate was 18.77 nM. Finally, the sensor system has been successfully applied in fluorescence imaging of glyphosate in living cells.

Unraveling the role of polysaccharide-goethite associations on glyphosate' adsorption-desorption dynamics and binding mechanisms

HYPOTHESIS

Glyphosate retention at environmental interfaces is strongly governed by adsorption and desorption processes. In particular, glyphosate can react with organo-mineral associations (OMAs) in soils, sediments, and aquatic environments. We hypothesize mineral-adsorbed biomacromolecules modulate the extent and rate of glyphosate adsorption and desorption where electrostatic and noncovalent interactions with organo-mineral surfaces are favored.

EXPERIMENTS

Here we use in-situ attenuated total reflectance Fourier-transform infrared, X-ray photoelectron spectroscopy, and batch experiments to characterize glyphosate' adsorption and desorption mechanisms and kinetics at an organo-mineral interface. Model polysaccharide-goethite OMAs are prepared with a range of organic (polysaccharide, PS) surface loadings. Sequential adsorption-desorption studies are conducted by introducing glyphosate and background electrolyte solutions, respectively, to PS-goethite OMAs.

FINDINGS

We find the extent of glyphosate adsorption at PS-goethite interfaces was reduced compared to that at the goethite interface. However, increased polysaccharide surface loading resulted in lower relative glyphosate desorption. At the same time, increased PS surface loading yielded slower glyphosate adsorption and desorption kinetics compared to corresponding processes at the goethite interface. We highlight that adsorbed PS promotes the formation of weak noncovalent interactions between glyphosate and PS-goethite OMAs, including the evolution of hydrogen bonds between (i) the amino group of glyphosate and PS and (ii) the phosphonate group of glyphosate and goethite. It is also observed that glyphosate' phosphonate group preferentially forms inner-sphere monodentate complexes with goethite in PS-goethite whereas bidentate configurations are favored on goethite.

User-friendly one-step disposable signal-on bioassay for glyphosate detection in water samples

The onsite detection of glyphosate requires an easy-to-handle, low-cost and disposable assay for untrained users as requested by the ASSURED guidelines. A new strategy based on the expression of fusion proteins is proposed here. A glyphosate oxidase derived from Bacillus subtilis and the 6E10 variant of the dye peroxidase from Pseudomonas putida, both fused with the carbohydrate binding module (CBM) 3a from Clostridium thermocellum, were designed and expressed, leading to GlyphOx-CBM and 6E10-CBM. Cell lysates were used to immobilise both enzymes on cotton buds' heads without any purification. The cotton buds exhibit glyphosate oxidase activity when dipped into a glyphosate-contaminated water sample containing the 6E10-CBM chromogenic substrates. The chromophore could be quantified both in the solution and on the cotton buds' heads. Photography followed by image analysis allows to detect glyphosate with a linear range of 0.25-2.5 mM and a limit of detection (LoD) of 0.12 mM. When the chromogenic substrates are replaced by luminol, the chemiluminescence reaction allows the detection of glyphosate with a linear range of 2-500 μM and a LoD of 0.45 μM. No interference was observed using glyphosate analogues (glycine, sarcosine, aminomethylphosphonic acid) or other herbicides used in a mixture. Only cysteine was found to inhibit 6E10-CBM. Two river waters spiked with glyphosate lead to recoveries of 64-131%. This work describes a very easy-to-handle and inexpensive signal-on bioassay for glyphosate detection in real surface water samples.

An ultrasensitive LC-MS/MS method for the determination of glyphosate, AMPA and glufosinate in water - analysis of surface and groundwater from a hydrographic basin in the Midwestern region of Brazil

The intensive use of glyphosate around the world in the last few decades demands constant monitoring of this compound and its metabolite in aquatic compartments. This work aimed to develop a sensitive method for the analysis of glyphosate, AMPA and glufosinate in water by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The method involves analyte concentration by lyophilization (20×) and direct injection on the LC-MS/MS, and was satisfactorily validated at a LOQ of 0.0025 μg L^-1. A total of 142 samples of surface and groundwater collected during the 2021/2022 dry and rainy seasons in the Rio Preto Hydrographic Basin were analyzed. All the 52 groundwater samples were positive for glyphosate (up to 1.5868 μg L^-1, dry season) and AMPA (up to 0.2751 μg L^-1, dry season). A total of 27 of the 90 surface water samples were positive for glyphosate (up to 0.0236 μg L^-1), and 31 samples for AMPA (up to 0.0086 μg L^-1), of which over 70 % collected during the dry season. Glufosinate was detected in only five samples, four in groundwater (up to 0.0256 μg L^-1). The levels found in the samples are much lower than the maximum levels established by the Brazilian legislation for glyphosate and/or AMPA and lower than the most critical toxicological endpoints for aquatic organisms. However, constant monitoring is necessary, demanding sensitive methods to allow the detection of the very low levels of these pesticides in water.

A New Family of Macrocyclic Polyamino Biphenolic Ligands: Acid-Base Study, Zn(II) Coordination and Glyphosate/AMPA Binding

In this study, the ligands 23,24-dihydroxy-3,6,9,12-tetraazatricyclo[17.3.1.1(14,18)]eicosatetra-1(23),14,16,18(24),19,21-hexaene, L1, and 26,27-dihidroxy-3,6,9,12,15-pentaazatricyclo[20.3.1.1(17,21)]eicosaepta-1(26),17,19,21(27),22,24-hexaene, L2, were synthesized: they represent a new class of molecules containing a biphenol unit inserted into a macrocyclic polyamine fragment. The previously synthesized L2 is obtained herein with a more advantageous procedure. The acid-base and Zn(II)-binding properties of L1 and L2 were investigated through potentiometric, UV-Vis, and fluorescence studies, revealing their possible use as chemosensors of H⁺ and Zn(II). The new peculiar design of L1 and L2 afforded the formation in an aqueous solution of stable Zn(II) mono (LogK 12.14 and 12.98 for L1 and L2, respectively) and dinuclear (LogK 10.16 for L2) complexes, which can be in turn exploited as metallo-receptors for the binding of external guests, such as the popular herbicide glyphosate (N-(phosphonomethyl)glycine, PMG) and its primary metabolite, the aminomethylphosphonic acid (AMPA). Potentiometric studies revealed that PMG forms more stable complexes than AMPA with both L1- and L2-Zn(II) complexes, moreover PMG showed higher affinity for L2 than for L1. Fluorescence studies showed instead that the L1-Zn(II) complex could signal the presence of AMPA through a partial quenching of the fluorescence emission. These studies unveiled therefore the utility of polyamino-phenolic ligands in the design of promising metallo-receptors for elusive environmental targets.

Fluorescent molecularly imprinted polymer particles for glyphosate detection using phase transfer agents

In this work, molecular imprinting was combined with direct fluorescence detection of the pesticide Glyphosate (GPS). Firstly, the solubility of highly polar GPS in organic solvents was improved by using lipophilic tetrabutylammonium (TBA⁺) and tetrahexylammonium (THA⁺) counterions. Secondly, to achieve fluorescence detection, a fluorescent crosslinker containing urea-binding motifs was used as a probe for GPS-TBA and GPS-THA salts in chloroform, generating stable complexes through hydrogen bond formation. The GPS/fluorescent dye complexes were imprinted into 2-3 nm fluorescent molecularly imprinted polymer (MIP) shells on the surface of sub-micron silica particles using chloroform as porogen. Thus, the MIP binding behavior could be easily evaluated by fluorescence titrations in suspension to monitor the spectral changes upon addition of the GPS analytes. While MIPs prepared with GPS-TBA and GPS-THA both displayed satisfactory imprinting following titration with the corresponding analytes in chloroform, GPS-THA MIPs displayed better selectivity against competing molecules. Moreover, the THA⁺ counterion was found to be a more powerful phase transfer agent than TBA⁺ in a biphasic assay, enabling the direct fluorescence detection and quantification of GPS in water. A limit of detection of 1.45 µM and a linear range of 5-55 µM were obtained, which match well with WHO guidelines for the acceptable daily intake of GPS in water (5.32 µM).

Development of a UHPLC-MS/MS method to enhance the detection of Glyphosate, AMPA and Glufosinate at sub-microgram / L levels in water samples

Glyphosate is the best-selling herbicide worldwide. The toxicity on ecosystems and the possible effects on human health have long been at the centre of a complex controversy concerning the authorisation for its use. The peculiar chemical-physical properties of glyphosate, AMPA and glufosinate make their determination at trace levels in the water a real analytical challenge. All three compounds can be derivatised to less polar ones and FMOC-Cl (9-fluorenylmethyl chloroformate) is the most common pre-column derivatisation reagent used for this analysis. It can be successfully combined with Ultra-High-Performance Liquid Chromatography with Mass Spectrometry (UHPLC-MS/MS) to determine all three analytes in one method as part of water monitoring programs. The developed method aims to determine glyphosate with AMPA and glufosinate at sub-micrograms/L levels in groundwater, surface and water by UHPLC-MS/MS after derivatisation with FMOC-Cl. The novelty of this method is its high simplicity, robustness and sensitivity allowing the identification and quantification of the compounds at the detection limits required by the European regulations (0.1 µg /L). No pre-concentration or purification steps (by using Solid Phase Extraction cartridges) are necessary for our method saving time and consumables costs. The method demonstrated an excellent linear relationship (R2 ≥ 0.999) in the concentration range from 0.025 to 10 µg /L for glyphosate and AMPA and 0.025 to 5 µg /L for glufosinate. The method Limit Of Quantification (LOQ) is 0.025 µg/L, the lowest among all previously published studies, and it was demonstrated according to the European SANTE guidelines.

Red-Emitting Polymerizable Guanidinium Dyes as Fluorescent Probes in Molecularly Imprinted Polymers for Glyphosate Detection

The development of methodologies to sense glyphosate has gained momentum due to its toxicological and ecotoxicological effects. In this work, a red-emitting and polymerizable guanidinium benzoxadiazole probe was developed for the fluorescence detection of glyphosate. The interaction of the fluorescent probe and the tetrabutylammonium salt of glyphosate was studied via UV/vis absorption and fluorescence spectroscopy in chloroform and acetonitrile. The selective recognition of glyphosate was achieved by preparing molecularly imprinted polymers, able to discriminate against other common herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (dicamba), as thin layers on submicron silica particles. The limits of detection of 4.8 µM and 0.6 µM were obtained for the sensing of glyphosate in chloroform and acetonitrile, respectively. The reported system shows promise for future application in the sensing of glyphosate through further optimization of the dye and the implementation of a biphasic assay with water/organic solvent mixtures for sensing in aqueous environmental samples.

Titanium dioxide-coated core-shell silica microspheres-based solid-phase extraction combined with sheathless capillary electrophoresis-mass spectrometry for analysis of glyphosate, glufosinate and their metabolites in baby foods

Because of their extremely low amount in complex samples, it is quite challenging to accurate determine residues of phosphorus-containing amino-acid-like herbicides (PAAHs) in food products. Here we develop novel core-shell mesoporous silica (CSMS) microspheres coated by titanium dioxide (CSMS@TiO2) for extraction and enrichment of PAAHs in baby foods. After the dispersive solid phase extraction (d-SPE), sheathless capillary electrophoresis-mass spectrometry (sheathless CE-MS) is utilized to achieve efficient separation and sensitive detection. The synthesized CSMS@TiO2 composites are characterized by various spectroscopic techniques, proving TiO2 is uniformly distributed onto the channel surface of CSMS. The composites have essential features that are favorable for adsorption of the analytes on the material for d-SPE, including uniform diameter (1.0 μm with a shell thickness of 133 nm), large perpendicular mesopores (15.6 nm), high surface area (101.1 m2/g) and large pore volume (0.4 cm3/g). Taking glyphosate, glufosinate and their main metabolites (aminomethylphosphonic acid and 3-methylphosphinicopropionic acid) as analytes, selective and efficient enrichment is achieved by CSMS@TiO2-based d-SPE through the affinity interaction between titanium dioxide and phosphate groups. Sensitive detection of target compounds is achieved with low limits of quantitation (LOQs) between 0.3-1.6 ng/mL and excellent inter/intra-day repeatability. The compounds in nine different commercial baby foods from local markets are analyzed using the proposed method. Good recoveries of 82.3-102.6% are achieved with low RSDs (n = 5) of 2.1-8.3%. Our study indicates that the proposed CSMS@TiO2-based d-SPE combined with sheathless CE-MS is an accurate and reliable approach for sensitive determination of trace-amount PAAHs and their metabolites in complex samples.

Electrochemical Microsensor for Microfluidic Glyphosate Monitoring in Water Using MIP-Based Concentrators

Glyphosate (GLY) is a broad-spectrum herbicide and is the most used pesticide worldwide. This vast usage has raised strong interest in the ecotoxicological impacts and human risks, with contamination of water being a major concern. Decentralized analytical techniques for water monitoring are of high importance. In this work, we present a small, low-cost, and time-effective electrochemical, chip-based microfluidic device for direct electrochemical detection of GLY downstream of a molecularly imprinted polymer (MIP) concentrator. We studied the electrochemical behavior of GLY and its metabolite aminomethylphosphonic acid (AMPA) using cyclic voltammetry with noble metal electrodes in acidic, neutral, and basic media. A chronoamperometric sensor protocol was developed for sensitive and selective GLY measurements on gold electrodes. The optimized protocol was transferred to a chip-based microsensor platform for online and real-time detection of GLY in a microfluidic setup. The results in the range from 0 to 50 μM GLY in 0.5 M H2SO4 show high linearity and a sensitivity of 10.3 ± 0.6 μA mm-2 mM-1 for the chip-based microfluidic platform. Successful recovery of GLY concentrated from untreated tap water and its precise detection from low volumes demonstrates the advantages of our system.

Determination of glyphosate, glufosinate and their major metabolites in urine by the UPLC-MS/MS method applicable to biomonitoring and epidemiological studies

The preoccupation concerning glyphosate (GLYP) has rapidly grown over recent years, and the availability of genetically modified crops that are resistant to GLYP or glufosinate (GLUF) has increased the use of these herbicides. The debate surrounding the carcinogenicity of GLYP has raised interest and the desire to gain information on the level of exposure of the population. GLYP and aminomethylphosphonic acid (AMPA) are commonly simultaneously analysed. GLUF is sometimes also monitored, but its major metabolite, 3-[hydroxy(methyl)phosphinoyl]propionic acid (3MPPA), is rarely present in the method. Using a pentafluorobenzyl derivative to extract the analytes from human urine, we present a method that contains four important analytes to monitor human exposure to GLYP and GLUF. The use of the flash freeze technique speeds up the extraction process and requires less organic solvent than conventional liquid-liquid extraction. The limits of detection in the low μg/L range enable the use of this method for epidemiological studies. The results obtained for 35 volunteers from the Quebec City area are presented with the results from multiple interlaboratory comparisons (G-EQUAS, HBM4EU and OSEQAS). This methodology is currently being used in the Maternal-Infant Research on Environmental Chemicals (MIREC-ENDO) study and in the Canadian Health Measures Survey (CHMS).

Rational Design of Molecularly Imprinted Polymers Using Quaternary Ammonium Cations for Glyphosate Detection

Molecularly imprinted polymers have emerged as cost-effective and rugged artificial selective sorbents for combination with different sensors. In this study, quaternary ammonium cations, as functional monomers, were systematically evaluated to design imprinted polymers for glyphosate as an important model compound for electrically charged and highly water-soluble chemical compounds. To this aim, a small pool of monomers were used including (3-acrylamidopropyl)trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, and diallyldimethylammonium chloride. The simultaneous interactions between three positively charged monomers and glyphosate were preliminary evaluated using statistical design of the experiment method. Afterwards, different polymers were synthesized at the gold surface of the quartz crystal microbalance sensor using optimized and not optimized glyphosate-monomers ratios. All synthesized polymers were characterized using atomic force microscopy, contact angle, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Evaluated functional monomers showed promise as highly efficient functional monomers, when they are used together and at the optimized ratio, as predicted by the statistical method. Obtained results from the modified sensors were used to develop a simple model describing the binding characteristics at the surface of the different synthesized polymers. This model helps to develop new synthesis strategies for rational design of the highly selective imprinted polymers and to use as a sensing platform for water soluble and polar targets.

Validation of a simple ion chromatography method for simultaneous determination of glyphosate, aminomethylphosphonic acid and ions of Public Health concern in water intended for human consumption

The herbicide glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) are generally studied in environmental samples in the investigation of contamination of soil, plants, water and food. Many analytical methods are based on liquid chromatography or high-performance liquid chromatography, with pre-column or post-column derivatization; in addition, the chromatograph can be coupled to mass spectrometers for detection and quantification. Gas chromatography and spectroscopic and electrochemical methods have also been used. In this work, a simple low-cost method is presented for the analysis of water intended for human consumption with the quantification not only of glyphosate and AMPA, but also of other ions of interest to public health (fluoride, chlorite, bromate, chloride, nitrite, nitrate, sulfate and phosphate). Based on ion chromatography with conductivity detection (chemical suppression of eluent conductivity), the key point in this method is the use of gradient elution with two eluents of different pH and ionic strength, not requiring derivatization. There is no interference from the other ions at higher concentrations. The detection limits obtained for glyphosate and AMPA were 15 μg L-1 and 80 μg L-1, respectively. As the method allows the analysis of a large number of samples, it has been successfully applied to monitoring the quality of tap water in 89 municipalities in the northeast region of the State of São Paulo, Brazil.

Simultaneous and direct determination of glyphosate and AMPA in water samples from the hydroponic cultivation of eucalyptus seedlings using HPLC-ICP-MS/MS

Glyphosate is the main herbicide currently used in the world due to wide applicability and efficiency in controlling weeds in many crops. However, its overuse may lead to undesirable impacts on the environment and to human health in the long run. This present study aimed to optimize and validate solid phase extraction (SPE) using an anionic resin for the simultaneous and direct determination of glyphosate and aminomethylphosphonic acid (AMPA) in water samples using high-performance liquid chromatography combined with inductively coupled plasma with triple quadrupole mass spectrometer (HPLC-ICP-MS/MS). The results showed that recovery percentage and relative standard deviation were 103.9 ± 7.9 and 99.40 ± 9.9% for glyphosate and AMPA, respectively. The validation certified that the method was precise, accurate, linear, and selective, with a limit of quantification of 1.09 and 0.29 μg L-1 for glyphosate and AMPA, respectively. The optimized methodology reached the concentration factor of 250 times and was successfully applied to analyze water samples from hydroponic cultivation of the eucalyptus seedlings. The results showed that the exudation process occurs at glyphosate doses starting from 2 L ha-1.

Field-amplified sample injection and sweeping micellar electrokinetic chromatography in analysis of glyphosate and aminomethylphosphonic acid in wheat

Glyphosate, a widely used herbicide, has been classified as probably carcinogenic to humans by the International Agency for Research on Cancer (IARC). In the present study a method based on Field-Amplified Sample Injection and Sweeping Micellar Electrokinetic Chromatography (FASI sweep-MEKC) has been developed and validated for determination of glyphosate and its microbial metabolite aminomethylphosphonic acid (AMPA) in wheat flour. The method involved a preliminary solid phase extraction for cleanup of the aqueous extracts from wheat flour, based sequentially on C18 and strong anion exchange cartridges, followed by derivatization using 9-fluorenylmethylchloroformate. Optimization of sample cleanup and derivatization procedure was carried out by a HPLC-UV method, whereas FASI sweep-MEKC was applied for achieving the sensitivity necessary for analysis of real samples. To this regard, optimum conditions involved the use of an extended path fused-silica capillary (80 cm total length, 50 μm, i.d.) filled with a high concentration buffer (sodium phosphate 100 mM, pH 2.2). Electrokinetic sampling was carried out at -10 kV with injection time of 700 s and the separation of the loaded analytes was performed under MEKC conditions using sodium phosphate buffer 50 mM at pH 2.2, supplemented with sodium dodecyl sulfate, 100 mM. The method was validated for linearity, precision, accuracy and sensitivity, showing that using conventional UV detection (210 nm) the achieved limit of quantitation (LOQ) values for both the analytes were widely lower than those set by Authorities. In particular, LOQ for glyphosate and AMPA were found to be 5 and 2.5 ng/mL, respectively, corresponding to 0.1 and 0.05 mg/kg, in wheat flour. The method, applied to commercially available real samples (wheat flour from different manufacturers) and to an experimental sample obtained by cv. Svevo wheat, can be considered as a convenient alternative to the existing approaches in analysis of complex matrices.

Advanced method for fabrication of molecularly imprinted mesoporous organosilica with highly sensitive and selective recognition of glyphosate

In this study, we synthesized molecularly imprinted mesoporous organosilica (MIMO) in the presence of a new precursor having a zwitterionic functional group and an imprint molecule, namely, glyphosate (MIMO-z). The precursor-glyphosate complex engaged in a typical base-catalyzed sol-gel reaction and the introduced zwitterion group remained intact in the framework after the extraction process had been completed. To test the rebinding performance of the target molecule, graphene quantum dots were encapsulated (MIMO-zQ) into pores and the fluorescence intensity change was monitored according to the concentration of glyphosate. When the MIMO-zQ suspension was diluted into the glyphosate solutions, notable fluorescence quenching occurred, right down to sub-nanomolar levels of concentration; 9.2 ± 0.18% quenching at 0.1 nM (0.017 ppb, 17 pg/mL). This result is one of the best reported to date for sensing using MIMO. The synthesized probe also exhibited a distinct signal compared to a series of competing compounds, aminomethylphosphonic acid and glycine; 4.3 ± 0.019% and 3.7 ± 0.041% quenching at 100 nM.

A simple liquid chromatography-high resolution mass spectrometry method for the determination of glyphosate and aminomethylphosphonic acid in human urine using cold-induced phase separation and hydrophilic pipette tip solid-phase extraction

Recently, the phenomenon of acute poisoning events caused by glyphosate (GLY) had frequently occurred all over the world. The present work reported a simple liquid chromatography-high resolution mass spectrometry (LC-HRMS) method for direct determination of GLY and its metabolite aminomethylphosphonic acid (AMPA) in human urine by combining cold-induced phase separation (CIPS) with hydrophilic pipette tip solid-phase extraction (PTSPE). First, a urine sample was mixed with acetonitrile at a 80% concentration to precipitate proteins. After centrifugation, the mixture was performed a CIPS at -20 °C to enrich GLY and AMPA (six-fold) in the lower water phase which was further performed PTSPE procedure. PTSPE as a miniaturized procedure of SPE, combined with a manual accu-jet® Pro Pipette Controller, was used to extract GLY and AMPA, in which a new type of hydrophilic adsorbent (HILIC powder) based on amide-modified silica was selected as the adsorption of GLY and AMPA. The key factors including the type and the amount of adsorbent, the loading extraction solution, the type and volume of eluent, and the number of aspirating/dispensing cycles were investigated in detail. Meanwhile, the selectivity and sensitivity of GLY and AMPA analysis were improved by the use of LC-HRMS based on targeted single ion monitoring (tSIM) mode without tedious derivatization. This method made a full use of the advantages of these techniques by combining efficient enrichment, effective extraction and selective separation in a simple way. Finally, a comprehensive validation of the method was rigorously executed and the results indicated that the validated method afforded desired linearity, precision, accuracy, and sensitivity.

A Case of ‘Muddling Through’? The Politics of Renewing Glyphosate Authorization in the European Union

Between 2012 and 2017, the European Commission struggled to achieve the renewal of glyphosate, an active ingredient of some broad-spectrum herbicides. As indicated by the International Agency for Research on Cancer, the chemical kills or suppresses all plant types; when applied at lower rates, it is a plant-growth regulator and desiccant. Glyphosate is used worldwide for agricultural and non-agricultural purposes. Once uncontroversial, new scientific evidence concerning the potential hazards of the substance has sparked a considerable debate in public and political spheres. In light of this sustained controversy, it came as a surprise when a qualified majority of European Union member states voted in favor of the Commission’s proposal to renew the approval of glyphosate for another five years. How was this outcome reached after many ‘no opinion’ votes? How are the member states dealing with the authorization’s renewal? Relying on document analyses and process tracing, we show in this study that the aforementioned renewal was attained due to a change in position on the part of German delegates, who voted in favor of the proposal instead of abstaining. By examining how the member states are addressing the renewal of the authorization, we found that both the countries that opposed renewal and those that supported it are now taking steps to reduce the use—or preparing the phaseout—of glyphosate. Due to domestic political considerations, however, the realization of these steps has so far proven to be difficult.

Determination of glyphosate, AMPA and glufosinate in dairy farm water from Argentina using a simplified UHPLC-MS/MS method

Argentina, together with the USA and Brazil, produces approximately 80% of the total worldwide glyphosate loadings. The development of a simplified ultra-high performance liquid chromatographic tandem mass spectrometric method (UHPLC-MS/MS) for the determination of glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate in water is described, including studies of several alternatives of 9-fluorenylmethylchloroformate (FMOC-Cl) derivatization and pretreatment steps. The proposed method includes acidification and neutralization of a low sample volume (3 mL), 2 hours derivatization step, cleanup with dichloromethane, followed by reverse phase UHPLC-MS/MS determination of the analytes. Figures of merit were satisfactory in terms of linearity, selectivity, accuracy and intermediate precision (%REC 70-105% with RSD < 15%). Limits of quantification (LOQ) were suitable for monitoring purposes (0.6, 0.2, 0.1 μg/L for glyphosate, AMPA and glufosinate respectively). The validated methodology was applied for the analysis of livestock wells waters from 40 dairy farms located in the central region of Argentina. Glyphosate and AMPA were quantified in 15% and 53% of the analyzed samples with concentrations ranging from 0.6-11.3 μg/L and 0.2-6.5 μg/L respectively. Greater concentrations of glyphosate were also verified in waters from open-reservoir tanks, which are directly exposed to the farm environment. In these cases glyphosate and AMPA occurrence increased, being quantified in the 33% and 61% of the samples with values ranging 0.6-21.2 μg/L and 0.2-4.2 μg/L respectively. Also in this case glufosinate was found in 52% samples at Collapse

Key Words

• AMPA
• Dairy farm environment
• FMOC-UHPLC-MS/MS
• Glufosinate
• Glyphosate
• Water

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MESH Headings

• Aminobutyrates/analysis
• Argentina
• Brazil
• Chromatography, High Pressure Liquid
• Dairying/statistics & numerical data
• Environmental Monitoring
• Farms
• Glycine/analogs & derivatives
• Glycine/analysis
• Herbicides/analysis
• Isoxazoles/analysis
• Tandem Mass Spectrometry
• Tetrazoles/analysis
• Water Pollutants, Chemical/analysis
• Glyphosate

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Affiliation(s)

Luisina Delma Demonte Programa de Investigación y Análisis de Residuos y Contaminantes Químicos (PRINARC), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2654, 3000 Santa Fe, Argentina; Consejo Nacional de Investigaciones Científicas Técnicas (CONICET), C1033AAJ Buenos Aires, Argentina
Nicolás Michlig Programa de Investigación y Análisis de Residuos y Contaminantes Químicos (PRINARC), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2654, 3000 Santa Fe, Argentina
Monica Gaggiotti Instituto Nacional de Tecnología Agropecuaria, EEA Rafaela, Ruta 34 km 227, 2300 Rafaela, Santa Fe, Argentina
Claudia Guadalupe Adam Consejo Nacional de Investigaciones Científicas Técnicas (CONICET), C1033AAJ Buenos Aires, Argentina; IQAL (UNL-CONICET), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, 3000 Santa Fe, Argentina
Horacio Ramón Beldoménico Programa de Investigación y Análisis de Residuos y Contaminantes Químicos (PRINARC), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2654, 3000 Santa Fe, Argentina
Maria Rosa Repetti Programa de Investigación y Análisis de Residuos y Contaminantes Químicos (PRINARC), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2654, 3000 Santa Fe, Argentina.

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