Analysis of glyphosate, AMPA, Glufosinate and MPPA with ION chromatography tandem mass spectrometry using A membrane suppressor in the ammonium form application to surface water of low to moderate salinity

One-step electrodeposition of MWCNTs-Cu MOF films for the ratiometric electrochemical analysis of glyphosate

Sensitive and accurate determination of glyphosate (GLYP) is vital for food safety and environmental protection. Herein, a novel electrochemical ratiometric biosensor was designed for the accurate quantification of GLYP through one-step electrodeposition of MWCNTs-Cu MOF films. MWCNTs-Cu MOF nanostructures were directly electro-synthesized in situ on the electrode from the precursor solution. The combination of Cu MOFs with MWCNTs not merely improved the conductivity of MOFs, but also enhanced the sensitivity of the biosensor. Furthermore, Cu sites within Cu MOFs were turned into CuCl to further amplify the current signal and enable the specific recognition of GLYP through competing reactions with the transformation of CuCl into non-electroactive Cu-GLYP. Meanwhile, internal reference molecules of methylene blue (MB) were incorporated to improve the measurement accuracy of GLYP for reducing unpredictable measurement errors aroused by environmental deviations. The ratiometric electrochemical sensor exhibited a high linearity with the logarithmic value of GLYP concentration from 0.5 nM to 400 nM. The detection limit was estimated to be as low as 0.014 nM. Finally, the present sensor with ratiometric signal export was applied for GLYP analysis in real samples with high sensitivity and accuracy. The simplicity and reliability of the ratiometric sensor make it a worthy and powerful tool for food and environmental monitoring. This design strategy also provides an avenue for the development of simple and efficient biosensors for other substances.

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 682 nm 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 570 nm. 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 570 nm. Meanwhile, the fluorescence intensity at the wavelength of 682 nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0-10 µM and 0.050-3.0 µg/mL with a detection limit of 0.547 µM and 0.0028 µg/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 0.30-3.0 µg/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.

Fate of glyphosate in lakes with varying trophic levels and its modification by root exudates of submerged macrophytes

Accelerated eutrophication in lakes reduces the number of submerged macrophytes and alters the residues of glyphosate and its degradation products. However, the effects of submerged macrophytes on the fate of glyphosate remain unclear. We investigated eight lakes with varying trophic levels along the middle and lower reaches of the Yangtze River in China, of which five lakes contained either glyphosate or aminomethylphosphate (AMPA). Glyphosate and AMPA residues were significantly positively correlated with the trophic levels of lakes (P < 0.01). In lakes, glyphosate is degraded through the AMPA and sarcosine pathways. Eight shared glyphosate-degrading enzymes and genes were observed in different lake sediments, corresponding to 44 degrading microorganisms. Glyphosate concentrations in sediments were significantly higher in lakes with lower abundances of soxA (sarcosine oxidase) and soxB (sarcosine oxidase) (P < 0.05). In the presence of submerged macrophytes, oxalic and malonic acids secreted by the roots of submerged macrophytes increased the abundance of glyphosate-degrading microorganisms containing soxA or soxB (P < 0.05). These results revealed that a decrease in the number of submerged macrophytes in eutrophic lakes may inhibit glyphosate degradation via the sarcosine pathway, leading to a decrease in glyphosate degradation and an increase in glyphosate residues.

Simultaneous analysis of degradation products of Novichok agents and conventional nerve agents in human urine by ion chromatography-tandem mass spectrometry using ammonium regeneration solution

An ion chromatography (IC)-tandem mass spectrometry (MS/MS) method to analyze nerve agent degradation products in human urine was developed. Six degradation products of conventional nerve agents and six Novichok agent degradation products were analyzed simultaneously despite their differences in hydrophilicity and acidity. Using ammonium regeneration solution improved the peak shapes greatly compared with the results obtained with the ordinary IC-MS/MS configuration. For urine samples, a simple pretreatment method of dilution with water and ultrafiltration was used. The detection limits of the nerve agent degradation products were sufficiently low (10-250 ng/mL) and the calibration curves showed acceptable linearity. Due to the absence of a derivatization step, throughput was higher than for our previous derivatization-liquid chromatography-MS/MS method.

Analysis of environmental pollutants using ion chromatography coupled with mass spectrometry: A review

The rise of emerging pollutants in the current environment and requirements of trace analysis in complex substrates pose challenges to modern analytical techniques. Ion chromatography coupled with mass spectrometry (IC-MS) is the preferred tool for analyzing emerging pollutants due to its excellent separation ability for polar and ionic compounds with small molecular weight and high detection sensitivity and selectivity. This paper reviews the progress of sample preparation and ion-exchange IC-MS methods in the analysis of several major categories of environmental polar and ionic pollutants including perchlorate, inorganic and organic phosphorus compounds, metalloids and heavy metals, polar pesticides, and disinfection by-products in past two decades. The comparison of various methods to reduce the influence of matrix effect and improve the accuracy and sensitivity of analysis are emphasized throughout the process from sample preparation to instrumental analysis. Furthermore, the human health risks of these pollutants in the environment with natural concentration levels in different environmental medias are also briefly discussed to raise public attention. Finally, the future challenges of IC-MS for analysis of environmental pollutants are briefly discussed.

A Turn-On Fluorescence Sensor Based on Nitrogen-Doped Carbon Dots and Cu2+ for Sensitively and Selectively Sensing Glyphosate

Glyphosate has excellent herbicidal activity, and its extensive use may induce residue in the environment and enter into humans living through the food chain, causing negative impact. Here, water-soluble 1.55 nm size nitrogen-doped carbon quantum dots (NCDs) with strong blue fluorescence were synthesized using sodium citrate and adenine. The maximum excitation and emission wavelengths of NCDs were 380 nm and 440 nm, respectively. The above synthesized NCDs were first used for the construction of a fluorescence sensor for glyphosate detection. It was found that Cu²⁺ could quench the fluorescence of NCDs effectively through the photoinduced electron transfer (PET) process, which was confirmed using fluorescence lifetime measurements. Additionally, the fluorescence was restored with the addition of glyphosate. Hence, a sensitive turn-on fluorescence sensor based on NCDs/Cu²⁺ for glyphosate analysis was developed. The LODs of glyphosate for water and rice samples were recorded as 0.021 μg/mL and 0.049 μg/mL, respectively. The sensor was applied successfully for ultrasensitive and selective detection of glyphosate in environmental water and rice samples with satisfied recoveries from 82.1% to 113.0% using a simple sample pretreatment technique. The proposed strategy can provide a significant potential for monitoring glyphosate residue in water and agricultural product samples.

Efficient Validation Strategies in Environmental Analytical Chemistry: A Focus on Organic Micropollutants in Water Samples

This article critically reviews analytical method validation and quality control applied to the environmental chemistry field. The review focuses on the determination of organic micropollutants (OMPs), specifically emerging contaminants and pesticides, in the aquatic environment. The analytical technique considered is (gas and liquid) chromatography coupled to mass spectrometry (MS), including high-resolution MS for wide-scope screening purposes. An analysis of current research practices outlined in the literature has been performed, and key issues and analytical challenges are identified and critically discussed. It is worth emphasizing the lack of specific guidelines applied to environmental analytical chemistry and the minimal regulation of OMPs in waters, which greatly affect method development and performance, requirements for method validation, and the subsequent application to samples. Finally, a proposal is made for method validation and data reporting, which can be understood as starting points for further discussion with specialists in environmental analytical chemistry.

A Novel Fluorescent Sensor Based on Aptamer and qPCR for Determination of Glyphosate in Tap Water

Glyphosate (GLYP) is a broad-spectrum, nonselective, organic phosphine postemergence herbicide registered for many food and nonfood fields. Herein, we developed a biosensor (Mbs@dsDNA) based on carboxylated modified magnetic beads incubated with NH2-polyA and then hybridized with polyT-glyphosate aptamer and complementary DNA. Afterwards, a quantitative detection method based on qPCR was established. When the glyphosate aptamer on Mbs@dsDNA specifically recognizes glyphosate, complementary DNA is released and then enters the qPCR signal amplification process. The linear range of the method was 0.6 μmol/L−30 mmol/L and the detection limit was set at 0.6 μmol/L. The recoveries in tap water ranged from 103.4 to 104.9% and the relative standard deviations (RSDs) were <1%. The aptamer proposed in this study has good potential for recognizing glyphosate. The detection method combined with qPCR might have good application prospects in detecting and supervising other pesticide residues.

Direct determination of glyphosate, aminomethylphosphonic acid and glufosinate in food samples with ion chromatography coupled to electrospray ionization tandem mass spectrometry

A fast and reliable method for the direct determination of the herbicide glyphosate, its major degradation product aminomethylphosphonic acid (AMPA) and glufosinate is presented for a variety of food matrices. The Quick Polar Pesticides in food of Plant Origin method (QuPPe-PO-Method) was used for extraction without further preconcentration or clean-up steps involving e.g. solid phase extraction (SPE). The method makes use of a commercially available high performance liquid chromatograph coupled to a tandem mass spectrometer with electrospray ionization (LC-ESI-MS/MS) - as present in many laboratories - equipped with an ion chromatography (IC)-column using an MS-compatible eluent made of 0.8% formic acid in water. Due to the absence of time-consuming clean-up procedures, strong matrix effects (ME) of up to 91% for AMPA in grapefruit can be observed, when comparing its sensitivity to that obtained for solvent-based standards. The limits of detection (LODs) were determined for the sample matrices apple, mushrooms, grapefruit, linseed, red lentils and wheat and they were found to be in the range of 0.09 to 0.8, 0.04 to 1 and 0.2 to 2 µg/kg for glyphosate, AMPA and glufosinate, respectively. For the same matrices the validation was carried out according to SANTE guidelines for different commodity groups by spiking them up prior to extraction to concentrations ranging from 10 to 400 µg/kg for matrices with high water content and from 10 to 800 µg/kg for matrices with low water content. When using solvent-based calibration under the use of isotopically labelled internal standards (ILIS) the recoveries were found to range from 84% to 120% and the relative standard deviations (RSD) range between 1% and 19% for glyphosate, AMPA and glufosinate at all fortification levels for all matrices investigated. Accordingly, the method was successfully introduced in our laboratory with limits of quantification (LOQs) of 10 µg/kg for glyphosate, AMPA and glufosinate in samples from SANTE commodity groups 1, 2, 4a and 5. The reliability and robustness of the method are demonstrated by showing a recovery control chart obtained for glyphosate in randomly selected samples from different commodity groups. Therefore, the samples were spiked up with 10 µg/kg of glyphosate during routine analysis, whereby all recoveries were found to be in the range between 70 and 120%.

Evaluation of pesticide pollution in the Gualeguay Basin: An extensive agriculture area in Argentina

The current agricultural production model was established in the 1990s based on the use of genetically modified organisms and agrochemicals, mainly pesticides. Despite pesticide spread and prevalence, data on the associated concentrations in surface watercourses are comparatively scarce. The aim of this work was to evaluate to what extent the >20 years of agricultural activity with the use of pesticides has impacted on the Gualeguay-River basin, with respect to the different stream orders: the tributary streams and main channel. Thirteen sites within the lower Gualeguay basin were sampled once every season (autumn, winter, spring, and summer) in 2017-2018. The samples were analyzed by gas chromatography time-of-flight mass-spectrometry (GC-TOF-MS) and ultraperformance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). The most frequently detected pesticide was glyphosate along with its metabolite (aminomethyl)phosphonic acid (AMPA), at 82 % and 71 % of surface water samples and 97 % and 92 % of bottom sediments, respectively; followed by atrazine in 73 % of the water samples. The concentrations of these compounds, each in their respective matrices, did not present sufficient statistically significant differences for differentiating a tributary stream from the main channel. Regardless of glyphosate's affinity for the suspended particulate and bottom sediments, over the entire basin the soluble fraction contributed on average to >80 % of the total concentration in surface water. Despite not being so frequently detected, certain insecticides, mostly deltamethrin, were likewise detected at concentrations above their water-quality guidelines for the protection of aquatic life, even in samples from the main channel. Upon comparison of the pesticide profiles of extensive- and horticultural-production systems in the country, atrazine emerged as a prime candidate to be used as a tracer of extensive agriculture contamination in the environment. Further research is required to establish to what degree pesticides used in agriculture and mobilized by watercourses have an impact on their associated wetland ecosystems.

Airborne polar pesticides in rural and mountain sites of North-Eastern Italy: An emerging air quality issue

North-Eastern Italy and in particular Veneto Region, stands out as a major centre of agriculture and viticulture which has rapidly expanded in the last decade with high productivity indexes. In this context, assessing atmospheric pollution caused by crop spraying with pesticides in rural areas and their transport to high-altitude remote sites is crucial to provide a basis for understanding possible impacts on the environment and population health. We aim to improve existing methods with a highly sensitive technique by using high pressure anion exchange chromatography coupled to a triple quadrupole mass spectrometer. Thus, a total of fourteen polar pesticides were determined in aerosol samples collected from August to December 2021 at Roncade (Venetian plain) and Col Margherita Observatory (Dolomites). The observatory was chosen as the background site as it is representative of the surrounding alpine region. Some samples revealed a substantial amount of cyanuric acid mainly at Roncade (mean concentration of 10 ± 10 ng m^-3), glyphosate and fosetyl-aluminium (0.1 ± 0.2 and 0.1 ± 0.1 ng m^-3, respectively). Surprisingly, some pesticides have been also found at Col Margherita, a high mountain background site, with concentrations an order of magnitude lower than at Roncade. This is the first time that fourteen polar pesticides have been assessed in the aerosol phase of the Po' Valley and detected at a high-altitude remote site, and consequently this study provides the first data on their occurrences in Italian aerosols. It represents a basis for the assessment of risks for humans.

Determination of Glufosinate-P-Ammonium in Soil Using Precolumn Derivation and Reversed-Phase High-Performance Liquid Chromatography

This study developed an analytical method to quantify glufosinate-P-ammonium (GLUF-P) in farmland soil using a reversed-phase high-performance liquid chromatography (HPLC) system with a fluorescence detector after derivatization. GLUF-P in farmland soil was extracted with a mixed alkaline solution and was further derivatized with 9-fluorenyl methyl chloroformate (FMOC) at 25 °C for 1 h. The derivatives were separated with an ACE-C18 column, gradient eluted with a mobile phase A of acetonitrile and a mobile phase B of 0.2% phosphoric acid solution, and finally determined by high-performance liquid chromatography (HPLC) with fluorescence detection at an excitation wavelength of 254 nm and an emission wavelength of 279.8 nm. The limits of detection (LODs) in the four types of soil ranged from 0.004 to 0.015 mg/kg, and the limits of quantification (LOQs) ranged from 0.0125 to 0.05 mg/kg. The mean recoveries of GLUF-P ranged from 94% to 119.8%, and the relative standard deviations (RSDs) varied between 2.8% and 9.0% when the spiked concentrations of GLUF-P were 0.1 mg/kg and 1.0 mg/kg, respectively. The coefficients of regression for the linearity equation were more than 0.99. The proposed method had high sensitivity and could be used for the determination of GLUF-P residues in farmland soil.

Comparing toxicity and biodegradation of racemic glufosinate and L-glufosinate in green algae Scenedesmus obliquus

Glufosinate-ammonium, a widely used chiral herbicide, has become the focus of attention because of its toxicity toward non-target organisms and its degradation behavior in the environment. With the introduction of L-glufosinate-ammonium products, the toxicity and environmental behavior of rac-glufosinate-ammonium and L-glufosinate-ammonium have become the subject of increasing interest. The overall goal of this study was to investigate the differences in toxicity and biodegradation of rac-glufosinate-ammonium and L-glufosinate-ammonium in an aquatic organism, Scenedesmus obliquus. The toxicity of rac-glufosinate-ammonium and L-glufosinate-ammonium to S. obliquus was compared by measuring EC₅₀, malondialdehyde (MDA) content, protein content and antioxidant enzyme activity. The 96-h EC₅₀ values of rac-glufosinate-ammonium and L-glufosinate-ammonium were 57.22 μg/mL and 25.55 μg/mL, respectively, which indicated that L-glufosinate-ammonium was more toxic to S. obliquus than rac-glufosinate-ammonium. Based on the MDA content, protein content, and antioxidant enzyme (SOD and CAT) activity, we found that L-glufosinate-ammonium could cause more serious oxidative damage than rac-glufosinate-ammonium. The residual amount of glufosinate-ammonium and its metabolites in the culture medium and S. obliquus were determined by HPLC-HRMS. Comparison of glufosinate-ammonium concentrations in algae-free and algae-containing media, showed that glufosinate-ammonium degradation in the S. obliquus system was significantly increased, and the degradation rate of L-glufosinate-ammonium was faster than that of D-glufosinate-ammonium. No enantiomerization was observed for pure L-glufosinate-ammonium treatment. N-acetyl-glufosinate was identified as the main metabolite of glufosinate-ammonium.

Determination of Glyphosate, Glufosinate, and Their Major Metabolites in Tea Infusions by Dual-Channel Capillary Electrophoresis following Solid-Phase Extraction

In this study, two analytical procedures were developed and validated using dual-channel capillary electrophoresis-coupled contactless conductivity detection (CE-C4D) followed by solid-phase extraction (SPE) for simultaneous determination of glyphosate (GLYP), glufosinate (GLUF), and their two major metabolites, aminomethylphosphonic acid (AMPA) and 3-(methylphosphinico) propionic acid (MPPA), respectively, in a popular beverage such as tea infusions. GLYP, GLUF, and AMPA were analyzed in the first channel using background electrolyte (BGE) of 1 mM histidine (His) adjusted to pH 2.75 by acetic acid (Ace). In contrast, MPPA was quantified in the second channel with a BGE of 30 mM His adjusted to pH 6.7 by 3-(N-morpholino) propanesulfonic acid (MOPS) and 10 µM of cetyltrimethylammonium bromide (CTAB). In addition, the samples of tea infusions were treated using SPE with 10 mL of 0.5 mM HCl in methanol as eluent. At the optimized conditions, the method detection limit (MDL) of GLYP, GLUF, AMPA, and MPPA is 0.80, 1.56, 0.56, and 0.54 μg/l, respectively. The methods were then applied to analyze four target compounds in 16 samples of tea infusions. GLYP was found in two infusion samples of oolong tea with concentrations ranging from 5.34 to 10.74 µg/L, and GLUF was recognized in three samples of green tea infusion in the range of 45.1-53.9 µg/L.

Anion Exchange Chromatography Coupled to Electrospray-Mass Spectrometry: An Efficient Tool for Food, Environment, and Biological Analysis

For over 50 years, ion chromatography has been demonstrated to be a successful technique used to quantify a wide range of ions and ionizable compounds, either organic or inorganic, in various matrices using conductimetric or electrochemical detection. It was only since 1996 that ion chromatography was coupled to electrospray-mass spectrometry, opening the field to new applications in complex matrices and the detection of compounds at trace levels. This review covers the recent developments of ion exchange chromatography and mass spectrometry. It focuses on the choice of mobile phases, column geometry, suppressors, make-up solvents and type of ionization sources reported in the literature. A brief overview of a large range of applications in food analysis, environmental analysis and bioanalysis is presented, and performances are discussed.

Assessment of Environmental Pollution and Human Exposure to Pesticides by Wastewater Analysis in a Seven-Year Study in Athens, Greece

Pesticides have been used in large amounts around the world for decades and are responsible for environmental pollution and various adverse effects on human health. Analysis of untreated wastewater can deliver useful information on pesticides’ use in a particular area and allow the assessment of human exposure to certain substances. A wide-scope screening method, based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry, was applied, using both target and suspect screening methodologies. Daily composite influent wastewater samples were collected for seven or eight consecutive days in Athens between 2014 and 2020 and analyzed for 756 pesticides, their environmental transformation products and their human metabolites. Forty pesticides were quantified at mean concentrations up to 4.9 µg/L (tralkoxydim). The most abundant class was fungicides followed by herbicides, insect repellents, insecticides and plant growth regulators. In addition, pesticide transformation products and/or metabolites were detected with high frequency, indicating that research should be focused on them. Human exposure was evaluated using the wastewater-based epidemiology (WBE) approach and 3-ethyl-carbamoyl benzoic acid and cis-1,2,3,6-tetrahydrophthalimide were proposed as potential WBE biomarkers. Wastewater analysis revealed the presence of unapproved pesticides and indicated that there is an urgent need to include more transformation products in target databases.

One-step purification/extraction method to access glyphosate, glufosinate, and their metabolites in natural waters

A new green method for trace level quantification of four herbicides, glyphosate (GLYP), glufosinate (GLUF), and their main metabolites, aminomethylphosphonic acid (AMPA) and 3-(methyl-phosphinico)-propionic acid (MPPA), was developed. The purification step without any derivatization was conducted by solid-phase extraction using Chelex-100 resin in the Fe (III) form, followed by elution with 5% NH4OH. The four analytes were quantified by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The developed extraction method was validated on five fresh and sea water matrices with mean recoveries ranging from 80.1% to 109.4% (relative standard deviation < 20%). The extraction conditions were evaluated and certified for the high applicability of the extraction method too. The limits of detection (ng/L) in the five water matrices were in ranges 0.70 - 4.0, 2.4 - 3.9, 1.8 - 4.7, and 1.6 - 4.0 for GLYP, AMPA, GLUF, and MPPA, respectively. The method was successfully applied to detect the four compounds in surface waters sampled along the Red River Delta region in July 2019. The highest concentrations were detected at 565, 1,330, 234, and 871 ng/L for GLYP, AMPA, GLUF, and MPPA, respectively. These results showed the potential capacity of this new method for convenient monitoring of herbicides and their metabolites in the diverse natural water system.