A liquid chromatography-miniature mass spectrometry (LC-Mini MS) method for quantitative analysis of risperidone and 9-hydroxyrisperidone in plasma.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a universal method for the quantitative analysis of small molecular drugs in therapeutic drug monitoring (TDM). Alternatively, liquid chromatography-miniature mass spectrometry (LC-Mini MS) is a simple operating technique for quantitative analysis. However, the wide chromatographic peaks and long retention times of TDM samples using the LC-Mini MS system deteriorated the accuracy and efficiency of quantitative analysis. Here, an optimized electrospray ionization (ESI) interface setup with a splitter valve and a capillary needle (I.D. 30 µm and O.D. 150 µm) of the LC-Mini MS system was acquired. The chromatographic peaks were narrower and smoother and the retention time was shorter for TDM compounds. Furthermore, a quantitative analysis method for risperidone and the active metabolite 9-hydroxyrisperidone in plasma was developed based on this optimal LC-Mini MS setup. The results showed that the calibration curves of risperidone and 9-hydroxyrisperidone had good linear ranges of 2-100 ng mL-1 (R2 = 0.9931) and 2-100 ng mL-1 (R2 = 0.9915), respectively. Finally, the matrix effects, recoveries and stability of risperidone and 9-hydroxyrisperidone samples were analyzed. The results satisfied the requirements of quantitative validation in routine TDM procedures.

Challenges in direct determination of Glyphosate and aminomethylphosphonic acid in water by liquid chromatography-tandem mass spectrometry at modified reverse phase columns: Effect of matrix interferences in fresh and hard water systems.

This study validated two underivatized methods (M1 and M2) according to the Eurachem guidelines to analyze the herbicide Glyphosate and its major metabolite aminomethylphosphonic acid simultaneously by liquid chromatography-tandem mass spectrometry in both fresh and hard waters. Samples were analyzed directly after filtration through 0.22 µm syringe filters in M1, while samples were acidified with acetic acid before filtration in M2. Spike recoveries were greater than 80% for Glyphosate and aminomethylphosphonic acid in both methods. The limit of quantitation was 0.5 µg/L for M1, and 0.1 µg/L for M2 by using matrix-matched calibrations. The linear regression coefficient of both methods was greater than 0.995. The expanded uncertainty was found to be less than 25% for both. Moreover, M1 has an additional mass spectral confirmation ability, and the column and the mobile phase used in M2 can be used to analyze the inert surfactant used in Glyphosate formulations, Polyethoxylated tallow amine. The accuracy of the developed methods was assured by participating in a proficiency testing program against M2 and conducting the t-test for results generated by both M1 and M2. Both methods, therefore, can be used to determine Glyphosate and aminomethylphosphonic acid content concurrently in fresh and hard waters.

Development and validation of an integrated microfluidic device with an in-line Surface Enhanced Raman Spectroscopy (SERS) detection of glyphosate in drinking water.

Glyphosate, also known as N-(phosphonomethyl)glycine, is one of the most widely used herbicides in the world. However, the controversy surrounding the toxicity of glyphosate and its main breakdown product, aminomethylphosphonic acid (AMPA), remains a serious public concern. Therefore, there is a clear need to develop a rapid, sensitive and automated alternative method for the quantification of glyphosate and AMPA. In this context, surface enhanced Raman spectroscopy (SERS) coupled with a microfluidic system for the determination of glyphosate in tap water was developed, optimized and validated. The design of the microfluidic configuration for this application was built constructed to integrate the synthesis of the SERS substrate through to the detection of the analyte. To optimize the microfluidic setup, a design of experiments approach was used to maximize the SERS signal of glyphosate. Subsequently, an approach based on the European guideline document SANTE/11312/2021 was used to validate the method in the range of 78-480 µg/L using the normalized band intensities. The limit of detection and quantification obtained for glyphosate were 40 and 78 µg/L, respectively. Recoveries were in the range 76-117%, while repeatability and intra-day reproducibility were ≤17%. Finally, the method was also tested for the determination of AMPA in tap water matrix and for the simultaneous detection of AMPA and glyphosate.

Simultaneous determination of isoxaflutole and its two metabolites in corn under field conditions by LC-MS/MS.

OBJECTIVE: An improved QuEChERS method was established and verified for simultaneous determination of isoxaflutole and its metabolites diketonitrile and benzoic acid analogue residues in corn and plants. This method was mainly used to study the digestion rule and final residue level of isoxaflutole and its metabolites in corn and plants. It was hoped that the safe use of isoxaflutole in corn can be achieved eventually. METHOD: The method was completed by means of ultra-performance liquid chromatography with triple quadrupole mass spectrometry. The extraction of the target substance was through acetonitrile solution containing 1% acetic acid, and the purification was through primary secondary amine, octadecylsilane and graphitized carbon black sorbent. RESULTS: In the method, the quantitative limits and detection limits of the three analytes were 0.005-0.01 and 0.001-0.003 mg kg-1 respectively. The half-life of isoxaflutole in the plants in Shandong and Anhui was 36.4 and 42.1 days respectively, and the digestion dynamics all conformed to the first-order kinetics. The final residues of isoxaflutole in green corn and mature corn were less than 0.02 mg kg-1 of the maximum residue limit set by the Codex Alimentarius Commission. CONCLUSIONS: The residual amount of isoxaflutole in corn and plants at harvest time was acceptable when isoxaflutole was applied once at a dose of 121.5 g a.i. ha-1 . © 2021 Society of Chemical Industry.

Assay of afoxolaner and determination of its related substances in commercial bulk batches of afoxolaner by reversed-phase HPLC method based on a short octadecyl column.

Afoxolaner is a new insecticidal and acaricidal active pharmaceutical ingredient (API) belonging to the isoxazoline family, widely prescribed for the control of fleas and ticks in dogs. A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method has been developed for the assay of afoxolaner and determination of its related compounds in bulk API lots of afoxolaner. The chromatographic separation of afoxolaner and its related compounds was achieved by gradient elution on a Zorbax-SB C18 column (50 mm × 4.6 mm i.d., 5 µm particle size) maintained at 40 °C. Mobile phase-A is composed of water and mobile phase-B is composed of acetonitrile/methanol (50/50, v/v). Analytes were monitored by UV detection at 225 nm with a flow rate of 2.0 mL/min. The stability-indicating capability of the method has been demonstrated by adequate separation of all the process related impurities and degradation products of afoxolaner generated by stress degradation of afoxolaner bulk drug substance under various stress conditions. This method was also successfully validated as per the current ICH guidelines for afoxolaner and Q6S07 (afoxolaner related substance) with respect to specificity, linearity (R2 > 0.999), detection limit (∼0.21 µg/mL), quantitation limit (∼0.70 µg/mL), accuracy, precision, and robustness. Due to its speed, high degree of selectivity, and accuracy, the proposed method is suitable and highly desirable in quality control laboratories for routine analysis of afoxolaner.

Novel High Affinity Sigma-1 Receptor Ligands from Minimal Ensemble Docking-Based Virtual Screening.

Sigma-1 receptor (S1R) is an intracellular, multi-functional, ligand operated protein that also acts as a chaperone. It is considered as a pluripotent drug target in several pathologies. The publication of agonist and antagonist bound receptor structures has paved the way for receptor-based in silico drug design. However, recent studies on this subject payed no attention to the structural differences of agonist and antagonist binding. In this work, we have developed a new ensemble docking-based virtual screening protocol utilizing both agonist and antagonist bound S1R structures. This protocol was used to screen our in-house compound library. The S1R binding affinities of the 40 highest ranked compounds were measured in competitive radioligand binding assays and the sigma-2 receptor (S2R) affinities of the best S1R binders were also determined. This way three novel high affinity S1R ligands were identified and one of them exhibited a notable S1R/S2R selectivity.

Residues and dietary intake risk assessments of clomazone, fomesafen, haloxyfop-methyl and its metabolite haloxyfop in spring soybean field ecosystem.

Soybean is an important oilseed crop, but weed can have a significant effect on soybean yield. Clomazone, fomesafen, and haloxyfop-methyl are high-efficacy herbicides, and the combination of these herbicides shows an ideal effect on weed control. However, the residues of these herbicides and their impacts on human health are still largely unknown. In the current study, a rapid, sensitive, and selective method using modified QuECHERS procedure combined with HPLC-MS/MS was established to detect these herbicides in soybean matrices. The limits of quantification were 0.01, 0.01 and 0.025 mg/kg for haloxyfop-methyl, haloxyfop and fomesafen, and 0.005, 0.005 and 0.0125 mg/kg for clomazone in green soybean, soybean grain, and straw, with the average recoveries ranging from 80% to 107%. The terminal residues of the target compounds were all below the corresponding limits of quantification. The dietary risk assessment showed that the risk quotient values were far below the acceptable human consumption levels.

Dissipation of Herbicide Methiozolin and Its Metabolites in Aerobic Sediment-Water Systems.

Methiozolin is a novel herbicide for controlling annual bluegrass. After applying 14C labelled methiozolin in two sediment (clay loam and sand)-water systems under aerobic conditions, its distribution, half-life, and metabolites within 300 days were investigated. The mass balance ranged within 92.0%-104.4% of applied radioactivity (AR). Radioactivity in the water declined sharply from 94.4% to 0.5% AR, while in the sediment it increased to 83.9% AR at 14 days before declining to 9.1% AR. The volatiles were minimal (< 0.5% AR), and the evolved labelled CO2 accounted for up to ~ 33.4% AR. From Radio-HPLC analysis, labelled methiozolin in water decreased from 108.9% to 0% AR, while a maximum of 15.1% AR remained in the sediment at the end. Eight metabolites were detected, all at minor levels and accounting for < 5.5% AR. The half-life of labelled methiozolin in the total sediment-water systems were 50.7 and 38.7 days for clay loam and sand, respectively.

Developing New 4-PIOL and 4-PHP Analogues for Photoinactivation of γ-Aminobutyric Acid Type A Receptors.

The critical roles played by GABAA receptors as inhibitory regulators of excitation in the central nervous system has been known for many years. Aberrant GABAA receptor function and trafficking deficits have also been associated with several diseases including anxiety, depression, epilepsy, and insomnia. As a consequence, important drug groups such as the benzodiazepines, barbiturates, and many general anesthetics have become established as modulators of GABAA receptor activity. Nevertheless, there is much we do not understand about the roles and mechanisms of GABAA receptors at neural network and systems levels. It is therefore crucial to develop novel technologies and especially chemical entities that can interrogate GABAA receptor function in the nervous system. Here, we describe the chemistry and characterization of a novel set of 4-PIOL and 4-PHP analogues synthesized with the aim of developing a toolkit of drugs that can photoinactivate GABAA receptors. Most of these new analogues show higher affinities/potencies compared with the respective lead compounds. This is indicative of cavernous areas being present near their binding sites that can be potentially associated with novel receptor interactions. The 4-PHP azide-analogue, 2d, possesses particularly impressive nanomolar affinity/potency and is an effective UV-inducible photoinhibitor of GABAA receptors with considerable potential for photocontrol of GABAA receptor function in situ.

Modeling the mobility of glyphosate from two contrasting agricultural soils in laboratory column experiments.

Glyphosate (GLP) currently is one of the most widely used herbicides worldwide. The persistence of GLP and its major metabolite, aminomethylphosphonic acid (AMPA) in the environment has been described by other authors. This study was aimed at comparing the GLP and AMPA behavior in sandy and loamy sand soils after spiking with enhanced (445 µg g-1) concentrations of GLP in herbicide KLINIK® (Nufarm, Austria) and bioaugmentation followed by 40 days weathering and a consistent three-stage leaching in a laboratory column experiment. Soil samples were obtained from mineral topsoil (0-10 cm) within former agricultural lands where soil parent material was formed by glacigenic deposits. The total amount of GLP and AMPA collected during three leaching stages was significantly (p<.05) higher from columns with sandy soil, compared to loamy sand soil. Bioaugmentation resulted in considerably lower concentrations of AMPA in leachates, especially in the sets with sandy soil (p=.01). Leachates were tested using FTIR spectroscopy and Daphnia magna. Statistical analysis of the changes in Ntot, Ctot, K+, Mg2+, Al3+, Ca2+, Mn2+ and Fe3+ concentrations in soils after the leaching experiment revealed that the loamy sand soil was likely to be more sensitive to the addition of GLP and bioaugmentation than sandy soil.

Fast analysis of glufosinate, glyphosate and its main metabolite, aminomethylphosphonic acid, in edible oils, by liquid chromatographycoupled with electrospray tandem mass spectrometry.

A method has been developed for the rapid, specific, accurate, precise and sensitive determination of glufosinate, glyphosate and its major metabolite, aminomethylphosphonic acid, in edible oils, by liquid chromatography coupled to tandem mass spectrometry. Oils were extracted with acidified water (1% formic acid), and the extracts were directly injected into an LC using a Hypercarb column as the stationary phase. The analytes were eluted by a mobile phase of methanol and water containing 1% acetic acid, and they were ionised by electrospray ionisation in negative ion mode. The method was validated and limits of quantification ranged from 5 µg kg-1 (aminomethylphosphonic acid) to 10 µg kg-1 (glyphosate and glufosinate). Three concentrations (10, 50 and 100 µg kg-1) were selected to perform recovery studies. Mean recoveries ranged from 81.4% to 119.4%. Intra and inter-day precision were lower than 19%. Different edible oils were analysed, and no residues of the studied herbicides were detected above limits of quantification.

Determination of glyphosate, AMPA, and glufosinate in honey by online solid-phase extraction-liquid chromatography-tandem mass spectrometry.

A simple method was developed for the simultaneous determination of glyphosate, its main degradation product (aminomethylphosphonic acid), and glufosinate in honey. Aqueous honey solutions were derivatised offline prior to direct analysis of the target analytes using online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry. Using the developed procedure, accuracies ranging from 95.2% to 105.3% were observed for all analytes at fortification levels of 5, 50, and 150 µg kg-1 with intra-day precisions ranging from 1.6% to 7.2%. The limit of quantitation (LOQ) was 1 µg kg-1 for each analyte. Two hundred honey samples were analysed for the three analytes with AMPA and glyphosate being most frequently detected (99.0% and 98.5% of samples tested, respectively). The concentrations of glyphosate were found to range from <1 to 49.8 µg kg-1 while those of its degradation product ranged from <1 to 50.1 µg kg-1. The ratio of glyphosate to AMPA was found to vary significantly amongst the samples where both analytes were present above the LOQ. Glufosinate was detected in 125 of 200 samples up to a maximum concentration of 33.0 µg kg-1.

Direct Determination of Glyphosate and its Metabolite AMPA in Soil Using Mixed-Mode Solid-Phase Purification and LC-MS/MS Determination on a Hypercarb Column.

Background: Although glyphosate is widely used in agriculture, information on its residue level in soils remains scarce partly because of the difficulty in its analysis. Objective: Develop and validate a method to directly analyze glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in soil. Method: Soils were extracted with 0.6 M KOH solution, and coextracted interferences were removed using a mixed-mode Bond Elut Plexa PAX®. The extracts were analyzed by LC-tandem MS fitted with a Hypercarb column and isotope-labeled (13C,15N) glyphosate and AMPA were used as internal standards. Results: LOQs were 0.05 mg/kg for both glyphosate and AMPA in soils. Correlation coefficients were ≥0.99, residuals were below 20%, and calibrations were linear in the range 0.02-1.0 µg/mL. The method was validated on five contrasting soils (Vertosol, Calcarosol, Chromosol, Sodosol, and Tenosol) commonly used for grain production in Australia. The recoveries for glyphosate and AMPA in the soils were 96-121 and 91-118%, respectively, with RSD in the range of 3-16%. Conclusions: This paper presents using the validated method in analysis glyphosate and AMPA in soils collected from crop production paddocks in Australia. The survey data showed that glyphosate and AMPA were detected in all collected soils, with concentrations ranging between 0.05 and 1.2 mg/kg. Highlights: The study demonstrates that the mixed-mode solid-phase extraction is effective in removing interferences and validates the use of Hypercarb as an alternative stationary phase for glyphosate and AMPA analysis from soils.

Biogenic transport of glyphosate in the presence of LDPE microplastics: A mesocosm experiment.

The accumulation of plastic debris and herbicide residues has become a huge challenge and poses many potential risks to environmental health and soil quality. In the present study, we investigated the transport of glyphosate and its main metabolite, aminomethylphosphonic acid (AMPA) via earthworms in the presence of different concentrations of light density polyethylene microplastics in the litter layer during a 14-day mesocosm experiment. The results showed earthworm gallery weight was negatively affected by the combination of glyphosate and microplastics. Glyphosate and AMPA concentrated in the first centimetre of the top soil layer and the downward transport of glyphosate and AMPA was only detected in the earthworm burrows, ranging from 0.04 to 4.25 µg g-1 for glyphosate and from 0.01 (less than limit of detection) to 0.76 µg g-1 for AMPA. The transport rate of glyphosate (including AMPA) from the litter layer into earthworm burrows ranged from 6.6 ±â€¯4.6% to 18.3 ±â€¯2.4%, depending on synergetic effects of microplastics and glyphosate application. The findings imply that earthworm activities strongly influence pollutant movement into the soil, which potentially affects soil ecosystems. Further studies focused on the fate of pollutants in the microenvironment of earthworm burrows are needed.

Effect of crop residues on interception and activity of prosulfocarb, pyroxasulfone, and trifluralin.

Crop residue retention on the soil surface in no-tillage system can intercept pre-emergent herbicides and reduce their efficacy. Three experiments were conducted to investigate the effect of crop residue amount (0, 1, 2 and 4 t ha-1), moisture (wet versus dry), type (wheat, barley, canola, chickpea and lupin) and age (fresh or aged for one year) on the interception and subsequent leaching of prosulfocarb, pyroxasulfone, and trifluralin from the residue into soil. Bioassays, using cucumber and annual ryegrass as indicator plants, were used to assess herbicide activity/availability in the soil and on the residue. Herbicide interception increased considerably as residue quantity increased from 2 to 4 t ha-1. After simulated rainfall, which washed herbicide into the soil, complete control of ryegrass occurred for trifluralin with 0 t ha-1 residue, for prosulfocarb with 0 and 1 t ha-1 residue, and for pyroxasulfone with all residue rates. Therefore, with rain or irrigation, pyroxasulfone was the herbicide least affected by high residue loads. Less chemical leached from the crop residue into the soil after rainfall, when prosulfocarb and trifluralin were applied to wet residue compared with dry residue, but the initial moisture condition had no effect on the leaching of pyroxasulfone from residue. If practically possible, farmers should minimise spraying prosulfocarb and trifluralin onto wet crop residue. Barley and wheat residues intercepted more herbicide than an equivalent mass of canola, chickpea or lupin residue, which was largely due to the increased ground cover with cereal residues. The effect of residue age on herbicide interception and leaching was relatively small and variable. Overall, more herbicide reached the soil when sprayed on one-year old residue than new residue, which was largely due to reduced ground cover with aged residue. A strong positive linear relationship existed between ground cover percentage and growth of bioassay species (r2 = 0.75). This means that there was little difference in the ability of residue to adsorb and retain herbicide between crop residue types and ages, such that farmers can simply use the ground cover of the crop residue to assess interception.

[Determination of glyphosate, glufosinate, and main metabolite aminomethylphosphonic acid residues in dry tea using ultra-high performance liquid chromatography-tandem mass spectrometry].

A method has been developed for the determination of glyphosate (GLY), glufosinate (GLUF), and the main metabolite aminomethylphosphonic acid (AMPA) residues in dry tea based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with pre-column derivatization. A systematic study of the effects of pretreatment methods including extraction and purification procedures was designed and carried out for the determination of GLY, GLUF, and AMPA. The results indicated that the optimal pretreatment method was as follows:the tea sample was first extracted by water in vortex, and then purified by a cation exchange solid-phase extraction column with the elution of 0.5% (v/v) formic acid aqueous solution. Finally, the eluant was derivatized by 9-fluorenylmethyl chloroformate, and the target compounds were separated on a C18 chromatographic column and analysed by UPLC-MS/MS (ESI+). GLY, GLUF, and AMPA showed good linearity in the range of 1-100 µ g/L, with correlation coefficients above 0.991. The limits of detection and limits of quantification were found to be 0.0160-0.0300 mg/kg and 0.0530-0.100 mg/kg, respectively. The average spiked recoveries of GLY, GLUF, and AMPA varied from 78.3% to 108% at three spiked levels (0.0500, 0.400, and 1.20 mg/kg), while the relative standard deviations ranged from 5.46% to 9.63%. The proposed method was utilized to detect 837 batches of tea samples. The detection ratios of GLY, GLUF, and AMPA were 3.46%, 0.24%, and 4.42%, respectively, while 0.24% of the investigated tea samples had values above maximum residue limits. The developed method is simple, rapid, sensitive, and accurate for the determination of GLY, GLUF, and AMPA in dry tea and may be used for routine analysis.

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

Flow Cytometry and Fluorescence Microscopy as Tools for Structural and Functional Analysis of Vacuoles Isolated from Yeast and Plant Cells.

A series of optimized protocols to isolate vacuoles from both yeast and plant cells, and to characterize the purified organelles at a functional and structural level, are described. For this purpose, we took advantage of the combined use of cell fractionation techniques with different fluorescence-based approaches namely flow cytometry, fluorescence microscopy and spectrofluorimetry. These protocols altogether constitute valuable tools for the study of vacuole structure and function, as well as for the high-throughput screening of drug libraries to identify new molecules that target the vacuole.

Herbicides in river water across the northeastern Italy: occurrence and spatial patterns of glyphosate, aminomethylphosphonic acid, and glufosinate ammonium.

Glyphosate and glufosinate ammonium are the active ingredients of commonly used herbicides. Active agricultural lands extend over a large part of the Veneto region (Eastern Po Valley, Italy) and glyphosate and glufosinate ammonium are widely used. Consequently, surface waters can be potentially contaminated. This study investigates the occurrence of glyphosate and glufosinate ammonium as well as aminomethylphosphonic acid (AMPA, the degradation product of glyphosate) in river water of Veneto. Eighty-six samples were collected in 2015 at multiple sampling points across the region. Samples were analyzed for the two target herbicides, AMPA as well as for other variables, including water temperature, pH, dissolved oxygen, conductivity, hardness, BOD, COD, inorganic ions, total nitrogen, total phosphorus, total suspended solids, arsenic, and lead. The average concentrations (all samples) were 0.17, 0.18, and 0.10 µg L-1 for glyphosate, AMPA, and glufosinate ammonium, respectively. The European upper tolerable level for pesticides (annual average 0.1 µg L-1) was often exceeded. Chemometric analysis was therefore applied to (i) investigate the relationships among water pollutants, (ii) detect the potential sources of water contamination, (iii) assess the effective water pollution of rivers by identifying river basins with anomalous pollution levels, and (iv) assess the spatial variability of detected sources. Factor analysis identified four factors interpreted as potential sources and processes (use of herbicides, leaching of fertilizers, urban/industrial discharges, and the biological activity on polluted or stagnant waters). A discriminant analysis revealed that the pollution from anthropogenic discharges is homogeneously present in surface water of Veneto, while biological activity and fertilizers present heterogeneous distributions. This study gives insights into the concentrations of herbicides in rivers flowing through a wide region that has heavy use of these chemicals in agriculture. The study also points out some hot-spots and suggests the future implementation of the current monitoring protocols and network.

Non-point source pollution of glyphosate and AMPA in a rural basin from the southeast Pampas, Argentina.

We measured the occurrence and seasonal variations of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in different environmental compartments within the limits of an agricultural basin. This topic is of high relevance since glyphosate is the most applied pesticide in agricultural systems worldwide. We were able to quantify the seasonal variations of glyphosate that result mainly from endo-drift inputs, that is, from direct spraying either onto genetically modified (GM) crops (i.e., soybean and maize) or onto weeds in no-till practices. We found that both glyphosate and AMPA accumulate in soil, but the metabolite accumulates to a greater extent due to its higher persistence. Knowing that glyphosate and AMPA were present in soils (> 93% of detection for both compounds), we aimed to study the dispersion to other environmental compartments (surface water, stream sediments, and groundwater), in order to establish the degree of non-point source pollution. Also, we assessed the relationship between the water-table depth and glyphosate and AMPA levels in groundwater. All of the studied compartments had variable levels of glyphosate and AMPA. The highest frequency of detections was found in the stream sediments samples (glyphosate 95%, AMPA 100%), followed by surface water (glyphosate 28%, AMPA 50%) and then groundwater (glyphosate 24%, AMPA 33%). Despite glyphosate being considered a molecule with low vertical mobility in soils, we found that its detection in groundwater was strongly associated with the month where glyphosate concentration in soil was the highest. However, we did not find a direct relation between groundwater table depth and glyphosate or AMPA detections. This is the first simultaneous study of glyphosate and AMPA seasonal variations in soil, groundwater, surface water, and sediments within a rural basin.