Glyphosate In Water Research Articles

D113 resin in-situ loaded with Fe3+ to develop glyphosate adsorbent with the characteristics of salt-resistance and the remarkable saturated adsorption capacity

There are inorganic salts in glyphosate production liquor and natural water bodies coexisting with glyphosate. It is imperative to develop a salt-tolerant adsorbent for glyphosate in water. Industrial D113 resin undergone two-step transformation to optimize the preparation of D113 in-situ loaded with Fe3+ (D113-Fe3+) as salt-resistance glyphosate adsorbent. The loading amount of Fe3+ on D113-Fe3+ is 3.5 mmol/g. The adsorption mechanism revealed that Fe3+ in D113-Fe3+ formed Fe-O-P bond with the phosphonate group of glyphosate. At 293 K, the maximum complex ratio of the adsorbed glyphosate to Fe3+ in D113-Fe3+ was 2.4:1. At 293 K, the remarkable saturated glyphosate adsorption capacity of D113-Fe3+ reached 1420.2 mg/g. In pK2 state of glyphosate, D113-Fe3+ featured its maximum adsorption capacity at the zero charge point 2.43 of D113-Fe3+ and 293 K. In glyphosate solution coexisting 0–16 % NaCl, D113-Fe3+ exhibited stable glyphosate adsorption capacity and salt-resistance compared with D201, D301 and 330 resin. The endothermic and spontaneous adsorption of glyphosate on D113-Fe3+ can fit Freundlich model and pseudo-second-order model. 2 mol/L NH3·H2O, 2 mol/L FeCl3 and 2 mol/L H2SO4 could all regenerate D113-Fe3+. The characteristics of salt-resistance and the remarkable saturated adsorption capacity made D113-Fe3+ comparable to all reported glyphosate adsorbents.

Using intrinsic‐resonance of an interdigitated microwave capacitor for detecting glyphosate‐based herbicide in water

AbstractGlyphosate‐based herbicides are the most used worldwide despite the fact that studies have shown their possible adverse effects on human health and the environment. Since the residues of these herbicides reach water bodies, their detection is considered an emergent research topic. In this work, the use of the intrinsic resonance of a microwave interdigitated capacitor fabricated on microstrip technology, is proposed for detecting the presence of glyphosate‐based herbicide in water. In addition, a sample holder is proposed to avoid the possible oxidation of the metal electrodes due to the direct contact with liquids. The proposed structure was designed to present its first intrinsic resonance at 1.95 GHz so that this resonance is shifted to 1.58 GHz when pure deionized water is used as sample. The sensor device was tested against 18 mixtures prepared with concentrations between 0% and 100% v/v of herbicide diluted in deionized water. Experimental measurements confirm that by using the intrinsic resonance parameters of the proposed structure, is possible to detect the presence of a glyphosate‐based herbicide. Finally, the results confirm the potential of the proposal as an alternative for real‐time, label‐free, and sensitive detection of glyphosate in water and they open the possibility of exploiting its use for the detection of other contaminants.

Adsorption of Glyphosate in Water Using Iron-Based Water Treatment Residuals Derived from Drinking Water Treatment Plants

Glyphosate, a broad-spectrum herbicide, poses a potential threat to human health and the ecosystem due to its toxicity. In this study, iron-based water treatment residuals (Fe-WTRs) were employed for glyphosate removal. The adsorption kinetics, isotherms, and thermodynamics, as well as the effects of pH, Fe-WTR particle size, and temperature, were explored. The results show that Fe-WTRs are an effective adsorbent for glyphosate adsorption, and the maximum uptake capacity was recorded as 30.25 mg/g. The Fe-WTR surface was positively charged, and low-valent iron dominated under acidic conditions, favoring glyphosate adsorption. Furthermore, smaller Fe-WTR particles (<0.125 mm) showed a faster absorption rate and 20% higher adsorption capacity than larger particles (2–5 mm). The kinetic analysis indicated that the adsorption process exhibits a two-step profile, conforming to the pseudo-second-order model, and the thermodynamic analysis indicated that it is a spontaneous, endothermic, and entropy-driven reaction. Finally, the Fourier transform infrared spectral analysis revealed that this process is mainly associated with the formation of metal phosphate through the ligand exchange of the phosphate groups of glyphosates with the hydroxyl groups of iron present in Fe-WTRs. In this study, we demonstrated the potential of Fe-WTRs as a cost-effective and efficient adsorbent for glyphosate removal.

A ratiometric fluorescence and colorimetry dual-signal sensing strategy based on o-phenylenediamine and AuNCs for determination of Cu2+ and glyphosate.

A ratiometric fluorescence sensing strategy has been developed for the determination of Cu2+ and glyphosate with high sensitivity and specificity based on OPD (o-phenylenediamine) and glutathione-stabilized gold nanoclusters (GSH-AuNCs). Water-soluble 1.75-nm size GSH-AuNCs with strong red fluorescence and maximum emission wavelength at 682nm were synthesized using GSH as the template. OPD was oxidized by Cu2+, which produced the bright yellow fluorescence oxidation product 2,3-diaminophenazine (DAP) with a maximum fluorescence emission peak at 570nm. When glyphosate existed in the system, the chelation between glyphosate and Cu2+ hindered the formation of DAP and reduced the fluorescence intensity of the system at the wavelength of 570nm. Meanwhile, the fluorescence intensity at the wavelength of 682nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0-10 µM and 0.050-3.0µg/mL with a detection limit of 0.547 µM and 0.0028µg/mL, respectively. The method was also used for the semi-quantitative determination of Cu2+ and glyphosate in water by fluorescence color changes visually detected by the naked eyes in the range 1.0-10 µM and 0.30-3.0µg/mL, respectively. The sensing strategy showed higher sensitivity, more obvious color changes, and better disturbance performance, satisfying with the detection demands of Cu2+ and glyphosate in environmental water samples. The study provides a reliable detection strategy in the environment safety fields.

Magnetic NiFe2O4/TiO2 heterostructures for the photocatalytic decontamination of glyphosate in water

This work investigated the synthesis and photocatalytic performance of NiFe2O4/TiO2 heterostructures for the decontamination of glyphosate in water. The adapted Pechini method effectively produced NiFe2O4/TiO2 structures. Doping TiO2 with Fe and its association with NiFe2O4 promoted the formation of the rutile phase. FTIR analysis confirmed the presence of Fe3+ ions in tetrahedral sites and Fe3+ and Ni2+ ions in octahedral sites, supporting the formation of an inverted spinel-type structure. SEM-EDS analysis revealed non-homogeneous TiO2 coating on the magnetic structures. Pure oxides (NiFe2O4 and TiO2) displayed homogeneous atomic distribution. NiFe2O4/TiO2 demonstrated superior photocatalytic performance compared to individual oxides, attributed to decreased electron-hole pair recombination as evidenced by photoluminescence results. Sample NiFe2O4/TiO2 displayed photocatalytic activity in the decomposition reaction, leading to a significant increase in phosphate ion concentration by a factor of 4 within 90 min. The H2O2 addition enhanced glyphosate degradation by scavenging electrons, reducing recombination, and increasing hydroxyl radical formation. The concentration of phosphate ions increased by 96 times with the use of H2O2. The photostability test performed using the best catalyst indicated a decrease in the photoactivity from the second photocatalytic cycle onwards. The catalyst exhibited toxicity only for A. salina, suggesting its sensitivity to Fe and TiO2. No toxicity was observed in L. minor and L. sativa seeds.

U-Shaped Fiber Sensor Based on Surface Plasmon Resonance of Gold Nanoparticles for Measuring Glyphosate in Water

U-Shaped Fiber Sensor Based on Surface Plasmon Resonance of Gold Nanoparticles for Measuring Glyphosate in Water

Evaluation of the adsorption capacity of glyphosate in a microbial cellulose composite

The objective of this project was to develop a composite based on microbial cellulose (CM), chitosan (Qs) and citric acid (AC) as a crosslinker at two different concentrations (4 and 6% w/v). The CM was obtained from the fermentation of fruit residues with a SCOBY (symbiotic consortium of bacteria and yeast). The composites were morphologically characterized by SEM and spectroscopy techniques (FTIR-ATR) as well as UV-VIS spectrophotometry with ninhydrin were used to evaluate the composite as an adsorbent for glyphosate in water; in the spectra obtained by FTIR, the representative vibrational bands of the functional groups belonging to chitosan and microbial cellulose were observed; for cellulose and chitosan composites with 4% citric acid in 1579 cm-1 , 1386 cm-1 , 1046 cm-1 and 853 cm-1 ; and for the 6% cellulose-chitosan-citric acid composite at 1573 cm-1 , 1380 cm-1 , 1056 cm-1 and 503 cm-1 , thus attributing cross linkage between the biopolymers. Post- adsorption FTIR-ATR analysis revealed significant changes possibly attributable to the adsorption of glyphosate in the cellulose composites. Further research is still being conducted to better understand this interaction and the involved mechanism; the goal is to comprehend how microbial cellulose can effectively adsorb glyphosate, which could have practical and efficient applications in the remediation of environments contaminated with this herbicide.

Ultra-Trace Electrochemical Determination of Glyphosate Using Bimetallic Metal–Organic Frameworks (MOFs) with Differential Pulse Voltammetry

Hierarchically bimetallic Zr-Cu metal–organic framework combined with 1,3,5-benzenetricarboxylic acid (Zr-CuBTC MOFs) was synthesized using hydrothermal reaction and used as modifier for investigation of non-electroactive glyphosate. These MOFs were dropcasted on a glassy carbon electrode (GCE) and non-electroactive glyphosate were tested by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Glyphosate in water was recognized by the difference of currents in spiked and non-spiked glyphosate samples. At the same time, CuBTC and Fe-CuBTC were investigated for the best material for sensor development. The results showed the bimetallic Zr-CuBTC MOF is the most promising for the determination of glyphosate. Morphological and structural studies showed the coordination of Cu2+ with the presence of Zr4+ ions with BTC ligands provided a highly porous framework with active surface area up to 1337 m2 g−1. The pore diameter and pore volume increased to 1.75 nm and 0.687 cm3 g−1, respectively. Under optimal conditions, Zr-CuBTC modified on GCE (Zr-CuBTC/GCE) sensor is able to indirectly detect glyphosate in a water environment at a detection limit as low as 9 × 10−13 M. The developed sensor was employed to determine glyphosate in the surface water samples collected from the Red River, North Vietnam. The results showed good recoveries (94.6–107.1%) which were in agreement with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) measurements. These results demonstrate the possibility of using this MOF material in sensor applications to determine trace pesticides in the contaminated water.

Assessment of chitosan-based adsorbents for glyphosate removal

Exposure to glyphosate produces various toxic effects, due to this, different methods have been evaluated for its elimination. The objective of this work was to formulate chitosan-based adsorbents and evaluate their efficiency in the removal of glyphosate in vitro. Four films were made by varying the weight ratio of silica/chitosan particles, and four sponges were made by varying the chitosan/chitosan ratio in a reticulated manner. Both adsorbents were characterized based on their porosity, water absorption, glyphosate removal, and reusability. It was found that increasing the porosity in both films and sponges resulted in an increase in the adsorption efficiency of glyphosate. The adsorption process exhibited a better fit in both adsorbents to the pseudo-second-order model. The adsorption of glyphosate to the films fit better with the Langmuir model, demonstrating that the process occurs in the form of a monolayer. In the case of sponges, the adsorption of glyphosate fit better with the Freundlich model, indicating that the process takes place in a multilayer form. Finally, when the reusability was evaluated, the adsorbents showed a loss of effectiveness. However, they still proved to be an efficient alternative for the removal of glyphosate in water, providing a cost-effective and environmentally friendly solution.

Construction of a stable S-scheme NiSnO3/g-C3N4 heterojunction on activated carbon fibre for the degradation of glyphosate in water under flow condition

Creating light-harvesting heterojunctions as a photocatalyst is critical for efficiently treating organics-laden wastewater. Yet the materials stabilization and limited reusability hinder their practical applications. In this study, an S-scheme heterojunction in the Sn-based perovskite and g-C3N4 (gCN) composite, supported on an activated carbon fiber (ACF) substrate, is developed for glyphosate (GLP) degradation under water under flow conditions. The reusable NiSnO3-gCN/ACF photocatalyst was synthesized using a simple wet impregnation and calcination method. The supported photocatalyst achieved 99% GLP-removal at 4 mL/min water flowrate and 1.25 g/m2 of photocatalyst loading in ACF. The photocatalyst showed a stable structure and repeat photocatalytic performance across 5 cycles despite prolonged visible light exposure under flow conditions. The materials stability is attributed to the effective dispersion of NiSnO3-gC3N4 in ACF, preventing the photocatalyst from elution in water flow. Radical trapping experiment revealed the superoxide and hydroxyl radicals as the primary reactive species in the GLP-degradation pathway. A plausible S-scheme mechanism was proposed for heterojunction formation, based on the high resolution deconvoluted spectra of X-ray photoelectron spectroscopy and the radical trapping experimental results. The inexpensive Sn-based perovskite synthesized in this study is indicated as an alternative to Ti-based perovskites for wastewater remediation application.

Seasonal variations in the levels of glyphosate in soil, water and crops from three farm settlements in Oyo state, Nigeria

This study investigated the concentration of glyphosate in water (groundwater and surface), soil (top and sub) on cassava and maize farms within 3 farm settlements (Akufo, Ilora and Otiri Ipapo) from Ido, Oyo and Iseyin Local Government Areas of Oyo state, Nigeria. Samples of Top and sub soil were taken from the farms while water was collected from wells (groundwater) and streams (surface water) around each farm settlement using standard methods. Crops (cassava and Maize) samples were collected from each of the selected farm after harvest. The samples were collected over a six-month period to reflect seasonal variation. The glyphosate levels were determined using HPLC-FLD after liquid-liquid extraction technique for water and soxhlet extraction for soil crops The pH, electrical conductivity (EC), total dissolved solids (TDS) values for groundwater were within the WHO limits while values recorded for surface water were above the WHO limits. The phosphate and nitrate values were high in surface water compared to groundwater. High concentration of the exchangeable cations were recorded at the top soil for all the farms with values ranging from 4.0 ± 0.1 to 8.2 ± 0.0 for Ca2+, 2.9 ± 0.0 to 5.1 ± 0.1 for Mg2+, 0.3 ± 0.2 to 0.55 ± 0.0 for Na+, and 0.32 ± 0.0 to 8.2 ± 0.0 for K+. the residual concentration of glyphosate taken from wells and taps (groundwater) were within the maximum concentration of glyphosate in drinking water (0.7 mgL−1). Glyphosate concentrations observed were higher in soil samples from all farm settlements during wet season compared to dry, higher concentrations were also observed in surface water during wet season (August) compared to dry, with Akufo farm settlement having the highest concentrations of 29.40 ± 0.83 mgL−1. The glyphosate residues were also higher in cassava (0.3 ± 0.0 mgKg−1) compared to maize (0.07 ± 0.08 mgKg−1) across each farm settlement. Generally, the higher concentrations observed during wet season in both soil and water samples were as a result of active farm activities during wet season and run off respectively. If herbicide usage is not properly monitored within these settlements, it can pose a threat to aquatic animals and humans around the settlements, thus a sustainable and conservative farming is advised.

Synthesis and application of a dual-functional fluorescent probe for sequential recognition of Zn2+and glyphosate

A novel fluorescent probe QL was designed and synthesized based on Schiff base by 2-hydrazinobenzothiazole to sequentially recognize Zn2+ and glyphosate. The probe QL was capable to detect Zn2+ in DMSO solution via fluorescence enhancement, and exhibited good selectivity and anti-interference ability. The combination mode was 1:2 between probe QL and Zn2+ according to the method of job’s plot, and the detection limit of probe QL for Zn2+ was found to be 4.51 × 10−8 M, which exhibited excellent sensitivity. Furthermore, the system QL-Zn2+ could detect glyphosate by causing fluorescence quenching response and with a color change from yellow to colorless for naked-eye detection. The detection limit for glyphosate was found to be 4.93 × 10−8 M, which was far below the Standards for Drinking Water Quality (GB5749-2006) acceptable limits (0.7 μg/mL for glyphosate). Notably, the probe QL and its complex QL-Zn2+ have been successfully applied to detect Zn2+ and glyphosate in water, respectively.

Ultrasensitive electrochemical detection of glyphosate using crumpled graphene/copper oxide nanocomposite

Glyphosate (Glyp) is an herbicide mainly employed worldwide. This has generated significant concern regarding the toxicological impacts and risks to humans, primarily water contamination. Therefore, the monitoring of glyphosate in water is demanding. Herein, we synthesized in one step crumpled graphene fully decorated with copper oxide nanoparticles (CG/CuO) for ultrasensitive electrochemical detections of glyphosate in water. The linear range was obtained by differential pulse voltammetry and performed in picomolar (5.00 – 25.00 ×10-12 M), demonstrating exceptional linearity, with limits of detection - LD (0.30 ×10-12 M) and quantification - LQ (0.90 ×10-12 M). Furthermore, the successful recovery analysis of enriched glyphosate from the distilled-deionized, river, groundwater, and untreated tap water, with great accuracy and precision achieved at low concentrations, demonstrated the advantages of our CG/CuO electrochemical sensor. This one-step strategy to prepare crumpled graphene-based copper composites is a promising method for future in-loco detection of Glyp.

Photodegradation of glyphosate in water and stimulation of by-products on algae growth

Glyphosate is the most widely used herbicide in global agricultural cultivation. However, little is known about the environmental risks associated with its migration and transformation. We conducted light irradiation experiments to study the dynamics and mechanism of photodegradation of glyphosate in ditches, ponds and lakes, and evaluated the effect of glyphosate photodegradation on algae growth through algae culture experiments. Our results showed that glyphosate in ditches, ponds and lakes could undergo photochemical degradation under sunlight irradiation with the production of phosphate, and the photodegradation rate of glyphosate in ditches could reach 86% after 96 h under sunlight irradiation. Hydroxyl radicals (•OH) was the main reactive oxygen species (ROS) for glyphosate photodegradation, and its steady-state concentrations in ditches, ponds and lakes were 6.22 × 10−17, 4.73 × 10−17, and 4.90 × 10−17 M. The fluorescence emission-excitation matrix (EEM) and other technologies further indicated that the humus components in dissolved organic matter (DOM) and nitrite were the main photosensitive substances producing •OH. In addition, the phosphate generated by glyphosate photodegradation could greatly promote the growth of Microcystis aeruginosa, thereby increasing the risk of eutrophication. Thus, glyphosate should be scientifically and reasonably applied to avoid environmental risks.

Ratiometric Sensing of Glyphosate in Water Using Dual Fluorescent Carbon Dots.

Glyphosate is a broad-spectrum pesticide used in crops and is found in many products used by industry and consumers. Unfortunately, glyphosate has been shown to have some toxicity toward many organisms found in our ecosystems and has been reported to have carcinogenic effects on humans. Hence, there is a need to develop novel nanosensors that are more sensitive and facile and permit rapid detection. Current optical-based assays are limited as they rely on changes in signal intensity, which can be affected by multiple factors in the sample. Herein, we report the development of a dual emissive carbon dot (CD) system that can be used to optically detect glyphosate pesticides in water at different pH levels. The fluorescent CDs emit blue and red fluorescence, which we exploit as a ratiometric self-referencing assay. We observe red fluorescence quenching with increasing concentrations of glyphosate in the solution, ascribed to the interaction of the glyphosate pesticide with the CD surface. The blue fluorescence remains unaffected and serves as a reference in this ratiometric approach. Using fluorescence quenching assays, a ratiometric response is observed in the ppm range with detection limits as low as 0.03 ppm. Our CDs can be used to detect other pesticides and contaminants in water, as cost-effective and simple environmental nanosensors.

Application of a novel hybrid MIL-53(Al)@rice husk for the adsorption of glyphosate in water: Characteristics and mechanism of the process

The development of new materials that have a high capacity to remove pollutants in water-based media is becoming increasingly important because of the serious contamination of water and the negative impact on biodiversity and public health. The presence of glyphosate in water, the most widely used herbicide worldwide, has triggered alerts owing to the collateral effects it may cause on human health. The main objective of the present study was to investigate the potential of the hybrid material MIL-53(Al)@RH for the adsorption of glyphosate in aqueous solution. The material was obtained following the methodology of MIL-53(Al) synthesis in the presence of hydrolyzed rice husk assisted by microwave. Batch adsorption experiments were carried out to evaluate the adsorbent dosage, pH0 solution effect, contact time, adsorbate concentration, and temperature effect. The results demonstrated that a maximum adsorption capacity of 296.95 mg g−1, at pH0 4 with a ratio of 0.04 g MIL-53(Al)@RH/50 mL of solution, was achieved in 30 min. The Avrami and pseudo-second order models appropriately described the adsorption kinetics and the equilibrium by Langmuir and Sips models. The enthalpy changes (ΔH°) determined propose an endothermic reaction governed by chemisorption, corroborating the kinetic and equilibrium settings. Hydrogen bonds, π*-π interactions, and complexation between the metal centers of MIL-53(Al) and the anionic groups of glyphosate were postulated to be involved as adsorption mechanisms. Finally, for practical application, MIL-53(Al)@RH was packed in a column for a fixed-bed test which revealed that the hybrid can remove glyphosate with an adsorption capacity of 76.304 mg L−1, utilizing 90% of the bed.

Solvation effects on glyphosate protonation and deprotonation states evaluated by mass spectrometry and explicit solvation simulations.

Glyphosate is a widely used herbicide, and its protonation and deprotonation sites are fundamental to understanding its properties. In this work, the sodiated, protonated, and deprotonated glyphosate were evaluated in the gas phase by infrared multiple photon dissociation spectroscopy to determine the exact nature of these coordination, protonation, and deprotonation states in the gas phase. In this context, Natural Bond Orbital analyses were carried out to unravel interactions that govern glyphosate (de)protonation states in the gas phase. The solvent effect on the protonation/deprotonation equilibria was also investigated by implicit (Solvation Model Based on Density and polarizable continuum models) and explicit solvation models (Monte Carlo and Molecular Dynamics simulations). These results show that glyphosate is protonated in the phosphonate group in the gas phase because of the strong hydrogen bond between the carboxylic oxygen (O7) and the protonated phosphonate group (O8-H19), while the most stable species in water is protonated at the amino group because of the preferential interaction of the NH2 + group and the solvent water molecules. Similarly, deprotonated glyphosate [Glyp-H]- was shown to be deprotonated at the phosphonate group in the gas phase but not in solution, also because of the preferential solvation of the NH2 + group present in the other deprotomers. Therefore, these results show that the stabilization of the protonated amino group by the solvent molecules is the governing factor of the (de)protonation equilibrium of glyphosate in water.

Solvent effects on glyphosate deprotonation: DFT theoretical studies

To better understand the molecular structures of glyphosate in different solvents, we have studied several possible conformations, and their relative abundances, of glyphosate and its deprotonated forms, in acetone, acetonitrile, DMSO, water, ethanol, carbon tetrachloride, dichloromethane and gas phase. We have also studied NMR and IR spectra of these species in these solvents. We found that the first protonation of glyphosate in water corresponds to the protonation on the amino group, the second protonation in the phosphonate group, the third protonation in the carboxylic group, and that when the molecule has a neutral charge, the most stable form is the zwitterionic specie with the protonated amino group and the phosphonate group.

Development of an inexpensive and rapidly preparable enzymatic pencil graphite biosensor for monitoring of glyphosate in waters

Glyphosate (GLY) is the most widely used non-selective broad-spectrum herbicide worldwide under well-reported side effects on the environment and human health. That's why it's necessary to control its presence in the environment. This work describes the development of an affordable, simple, and accurate electrochemical biosensor using a pencil graphite electrode as support, a horseradish peroxidase enzyme immobilized on a polysulfone membrane doped with multi-walled carbon nanotubes. The developed electrochemical sensor was used in the determination of GLY in river and drinking water samples. Cyclic voltammetry and amperometry were used as electrochemical detection techniques for the characterization and analytical application of the developed biosensor. The working mechanism of the biosensor is based on the inhibition of the peroxidase enzyme by GLY. Under optimal experimental conditions, the biosensor showed a linear response in the concentration range of 0.1 to 10 mg L−1. The limits of detection and quantification are 0.025 ± 0.002 and 0.084 ± 0.007 mg L−1, respectively, which covers the maximum residual limit established by the EPA for drinking water (0.7 mg L−1). The proposed biosensor demonstrated high reproducibility, excellent analytical performance, repeatability, and accuracy. The sensor proved to be selective against other pesticides, organic acids, and inorganic salts. Application on real samples showed recovery rates ranging between 98.18 ± 0.11 % and 97.32 ± 0.23 %. The analytical features of the proposed biosensor make it an effective and useful tool for the detection of GLY for environmental analysis.

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).