Analysis of glyphosate residues in cereals using liquid chromatography-mass spectrometry (LC-MS/MS)

A method for the quantitative analysis of polar anionic pesticides in milk/infant formula, cereals and fruit and vegetables using ion chromatography coupled to tandem mass spectrometry

Polar pesticides such as anionic or ionisable compounds have always provided a challenge for analytical chemists. Methods of analysis have been developed using a range of techniques including normal phase chromatography, ion-pairing, derivatisation and HILIC or multi-mode chromatography. These work well with some of these compounds but, except for HILIC, all of them have their limitations and none of them cover the range required by legislation. Some of these compounds, glyphosate, chlorate and phosphonic acid, are found regularly in a range of food matrices, and therefore reliable methods of analysis are essential. This study describes an ion chromatography method with tandem mass spectrometry detection which not only covers the full range of compounds required by legislation but also can be expanded to include other anionic or ionisable pesticides and metabolites. These include glyphosate and its metabolites, glufosinate and its metabolites, ethephon and its metabolites as well as fosetyl aluminium, chlorate and perchlorate. The method is fully validated according to the performance criteria from the SANTE guidelines for the analysis of pesticides in food and feed over a wide range of matrices, including milk, infant formula, cereals and fruits and vegetables. Over 300 food samples have analysed as part of our routine monitoring program.

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.

Associations of glyphosate exposure and serum sex steroid hormones among 6-19-year-old children and adolescents

Glyphosate, ranked as one of the most widely used herbicides in the world, has raised concerns about its potential disruptive effects on sex hormones. However, limited human evidence was available, especially for children and adolescents. The present study aimed to examine the associations between exposure to glyphosate and sex hormones among participants aged 6-19 years, utilizing data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2013 and 2016. Children and adolescents who had available data on urinary glyphosate, serum sex steroid hormones, including testosterone (TT), estradiol (E2) and sex hormone binding globulin (SHBG), and covariates were selected. Additionally, the ratio of TT to E2 (TT/E2) and the free androgen index (FAI), which was calculated using TT/SHBG, were also included as sex hormone indicators. Survey regression statistical modeling was used to examine the associations between urinary glyphosate concentration and sex hormone indicators by age and sex group. Among the 964 participants, 83.71% had been exposed to glyphosate (>lower limit of detection). The survey regression revealed a marginally negative association between urinary glyphosate and E2 in the overall population, while this association was more pronounced in adolescents with a significant trend. In further sex-stratified analyses among adolescents, a significant decrease in E2, FAI, and TT (p trend <0.05) was observed in female adolescents for the highest quartile of urinary glyphosate compared to the lowest quartile. However, no similar association was observed among male adolescents. Our findings suggest that exposure to glyphosate at the current level may decrease the levels of sex steroids in adolescents, particularly female adolescents. Considering the cross-sectional study design, further research is needed to confirm our findings.

Quantitation of glyphosate, glufosinate, and AMPA in drinking water and surface waters using direct injection and charged-surface ultra-high performance liquid chromatography-tandem mass spectrometry

Herbicides glyphosate (N-(phosphonomethyl)glycine) and glufosinate (2-amino-4-(hydroxymethylphosphinyl)butanoic acid) and the main transformation product of glyphosate, aminomethanephosphonic acid (AMPA), are challenging to analyze for in environmental samples. The quantitative method developed by this study adapts previously standardized dechlorination procedures coupled to a novel charged surface C18 column, ultra-high performance liquid chromatography-tandem mass spectrometry, polarity switching, and direct injection. The method was applied to chlorinated tap water, as well as river samples, collected in the City of Winnipeg and rural Manitoba, Canada. Using only syringe filtration without derivatization, the validated method resulted in good accuracies in both tap and surface water, at both 2 and 20 μg L-1. Method limits of detection (MLD) and quantification (MLQ) ranged from 0.022/0.074 to 0.11/0.36 μg L-1, with precisions of 0.46-2.2% (intraday) and 1.3-7.3% (interday). The mean (SEM) of the pesticides in μg L-1 for tap water were 0.11 (0.007) (AMPA), glufosinate and glyphosate < MLDs; and for Red River water were 0.56 (0.045) (AMPA), glufosinate < MLQ, and glyphosate 0.40 (0.072). For the smaller tributaries, glufosinate was >MLD but < MLQ once and that was for Shannon Creek at 0.2 μg L-1. For the remaining rivers, the mean concentrations ranged from 0.31 to 3.1 μg L-1 for AMPA, and 0.087-0.53 μg L-1 for glyphosate. The method will be ideal for supporting monitoring and risk assessment programs that require high throughput sampling and quantitative methods capable of producing robust results that leverages chromatographic and mass spectrometric paradigms instead of being extraction technology focused.

Effect of temperature on the degradation of glyphosate by Mn-oxide: Products and pathways of degradation

Glyphosate is the most commonly used herbicide in the United States. In the environment, glyphosate residues can either degrade into more toxic and persistent byproducts such as aminomethylphosphonic acid (AMPA) or environmentally benign species such as sarcosine or glycine. In this research, the birnessite-catalyzed degradation of glyphosate was studied under environmentally relevant temperatures (10-40 °C) using high-performance liquid chromatography, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and theoretical calculations. Our results show a temperature-dependent degradation pathway preference for AMPA and glycine production. The AMPA and glycine pathways are competitive at short reaction times, but the glycine pathway became increasingly preferred as reaction time and temperature increased. The measured free energy barriers are comparable for both the glycine and AMPA pathways (93.5 kJ mol-1 for glycine and 97.1 kJ mol-1 for AMPA); however, the entropic energy penalty for the AMPA pathway is significantly greater than the glycine pathway (-TΔS‡ = 26.2 and 42.8 kJ mol-1 for glycine and AMPA, respectively). These findings provide possible routes for biasing glyphosate degradation towards safer products, thus to decrease the overall environmental toxicity.

Diverging fates of cadmium and glyphosate during pasta cooking

Durum wheat cultivars with varying abilities to accumulate cadmium were grown and treated in the field with a glyphosate-containing herbicide at different stages of maturity to produce grain with higher and lower concentrations of cadmium (0.066-0.214 mg/kg) and glyphosate (0.474-0.874 mg/kg). The grain was milled, and fractions were analysed for cadmium and glyphosate. The highest concentrations for both cadmium and glyphosate were associated with bran and shorts, although the percentage of total cadmium mass in bran (23-25%) was less than glyphosate (38%). The preparation of dried pasta from semolina and flour milling fractions reduced concentrations by a factor of 1.8 for glyphosate and 1.4 for cadmium. Dried pasta was cooked and analysed along with the cooking water for cadmium and glyphosate at seven-time points from 0 to 15 min. Concentrations of glyphosate in cooked pasta decreased significantly with cooking time; no decrease was observed for cadmium concentrations. Analysis of cooking water demonstrated that glyphosate migrated from pasta to the cooking water. After 15 min of cooking, approximately 73% of the total glyphosate mass had transferred from pasta to cooking water. Over the same time period, only 5% of the total cadmium mass had transferred from pasta to cooking water.

Oilseed Rape, Wheat, and Barley Grain Contamination as Affected by Different Glyphosate Usage

Glyphosate is one of the most widely used herbicides, but is still in the spotlight due to its controversial impact on the environment and human health. The main purpose of this study was to explore the effects of different glyphosate usages on harvested grain/seed contamination. Two field experiments of different glyphosate usage were carried out in Central Lithuania during 2015-2021. The first experiment was a pre-harvest application, with two timings, the first according to the label (14-10 days), and the other applied 4-2 days before harvest (off-label), performed in winter wheat and spring barley in 2015 and 2016. The second experiment consisted of glyphosate applications at label rate (1.44 kg ha^-1) and double dose rate (2.88 kg ha^-1) at two application timings (pre-emergence of crop and at pre-harvest), conducted in spring wheat and spring oilseed rape in 2019-2021. The results suggest that pre-emergence application at both dose rates did not affect the harvested spring wheat grain or spring oilseed rape seeds-no residues were found. The use of glyphosate at pre-harvest, despite the dosage and application timing, led to glyphosate's, as well as its metabolite, aminomethosphonic acid's, occurrence in grain/seeds, but the amounts did not reach the maximum residue levels according to Regulation (EC) No. 293/2013. The grain storage test showed that glyphosate residues remain in grain/seeds at steady concentrations for longer than one year. A one year study of glyphosate distribution within main and secondary products showed that glyphosate residues were mainly concentrated in wheat bran and oilseed rape meal, while no residues found in cold-pressed oil and wheat white flour, when glyphosate used at pre-harvest at the label rate.

Association of Lifetime Exposure to Glyphosate and Aminomethylphosphonic Acid (AMPA) with Liver Inflammation and Metabolic Syndrome at Young Adulthood: Findings from the CHAMACOS Study

BACKGROUND

The prevalence of liver disorders and metabolic syndrome has increased among youth. Glyphosate, the most widely used herbicide worldwide, could contribute to the development of these conditions.

OBJECTIVE

We aimed to assess whether lifetime exposure to glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), is associated with elevated liver transaminases and metabolic syndrome among young adults.

METHODS

We conducted a prospective cohort study (n = 480 mother-child dyads) and a nested case-control study (n = 60 cases with elevated liver transaminases and 91 controls) using data from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS). We measured glyphosate and AMPA concentrations in urine samples collected during pregnancy and at child ages 5, 14, and 18 y from cases and controls. We calculated glyphosate residue concentrations: [glyphosate  +   ( 1.5 × AMPA ) ]. We estimated the amount of agricultural-use glyphosate applied within a 1 - km radius of every residence from pregnancy to age 5 y for the full cohort using California Pesticide Use Reporting data. We assessed liver transaminases and metabolic syndrome at 18 y of age.

RESULTS

Urinary AMPA at age 5 y was associated with elevated transaminases [relative risk (RR) per 2 - fold increase = 1.27 , 95% confidence interval (CI): 1.06, 1.53] and metabolic syndrome (RR = 2.07 , 95% CI: 1.38, 3.11). Urinary AMPA and glyphosate residues at age 14 y were associated with metabolic syndrome [RR = 1.80 (95% CI: 1.10, 2.93) and RR = 1.88 (95% CI: 1.03, 3.42), respectively]. Overall, a 2-fold increase in urinary AMPA during childhood was associated with a 14% and a 55% increased risk of elevated liver transaminases and metabolic syndrome, respectively. Living near agricultural glyphosate applications during early childhood (birth to 5 y of age) was also associated with metabolic syndrome at age 18 y in the case-control group (RR = 1.53 , 95% CI: 1.16, 2.02).

DISCUSSION

Childhood exposure to glyphosate and AMPA may increase risk of liver and cardiometabolic disorders in early adulthood, which could lead to more serious diseases later in life. https://doi.org/10.1289/EHP11721.

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%.

Pre-Conceptional Exposure to Glyphosate Affects the Maternal Hepatic and Ovarian Proteome

Exposure to glyphosate (GLY), a commonly used herbicide, is supported by urinary detection and associated with shortened gestation in women. This study tested the hypothesis that chronic low-dose pre-conceptional GLY exposure would affect maternal ovarian function mid- and post-gestation. Mice (C57BL/6; n = 40) were exposed per os to saline vehicle control (CT; n = 20) or GLY (2 mg/kg; n = 20) daily for 10 weeks starting at 7 weeks of age. Post-exposure, females were impregnated and euthanized at gestation day 14 (GD14) or post-weaning (PW). Pregnancy success was reduced from 75% to 55% by GLY exposure. No treatment effect (p > .05) on body weight, maternal serum 17β-estradiol, or litter size was noted. Ovarian weight was unaffected or reduced (p < .05) by GLY in GD14 and PW dams, respectively. Exposure to GLY decreased (p < .05) PW ovarian secondary follicle number with no other follicle composition impacts. Protein abundance analysis by LC-MS/MS identified that GLY altered (p < .05) 26 ovarian and 41 hepatic proteins in GD14 dams and 39 hepatic proteins in PW dams. In GD14 dams, GLY increased ovarian protein abundance of SEC16A (p < .05; 29-fold) and hepatic RPS27L and GM4952 (p < .05; ∼4-fold). In both GD14 and PW dams, GLY exposure increased (p < .05) hepatic RPS4 and decreased (p < .05) ECHDC3. Pathway analysis using DAVID identified 10 GLY hepatic pathway targets with FDR ≤ 0.07 in GD14 dams.

A Method for the Analysis of Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Human Urine Using Liquid Chromatography-Tandem Mass Spectrometry

The extensive use of herbicides, such as glyphosate and glufosinate, in crop production during recent decades has raised concerns about human exposure. Nevertheless, analysis of trace levels of these herbicides in human biospecimens has been challenging. Here, we describe a method for the determination of urinary glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate using liquid chromatography-tandem mass spectrometry (LC−MS/MS). The method was optimized using isotopically labelled internal standards (13C2, 15N-glyphosate, 13C, 15N, D2-AMPA, and D3-glufosinate) and solid-phase extraction (SPE) with cation-exchange and anion-exchange cartridges. The method provides excellent chromatographic retention, resolution and peak shape of target analytes without the need for strong acidic mobile phases and derivatization steps. The instrument linearity was in the range of 0.1−100 ng/mL, with R > 0.99 in the matrix for all analytes. The method detection limits (MDLs) and the method quantification limits (MQLs) were in the ranges of 0.12 (AMPA and glufosinate)−0.14 (glyphosate) ng/mL and 0.40 (AMPA)−0.48 (glyphosate) ng/mL, respectively. The recoveries of analytes spiked into urine matrix ranged from 79.1% to 119%, with coefficients of variation (CVs) of 4−10%. Repeated analysis of samples for over 2 weeks showed intra-day and inter-day analytical variations of 3.13−10.8% and 5.93−12.9%, respectively. The matrix effects for glyphosate, AMPA, and glufosinate spiked into urine matrix averaged −14.4%, 13.2%, and 22.2%, respectively. The method was further validated through the analysis of external quality assurance proficiency test (PT) urine samples. The method offers optimal sensitivity, accuracy, and precision for the urine-based assessment of human exposure to glyphosate, AMPA, and glufosinate.

Glyphosate at low doses changes the physiology and increases the productivity of common bean as affected by sowing seasons

Glyphosate applied at low doses can stimulate photosynthesis and yield. The objective of this study was to evaluate the application of low doses of glyphosate and sowing seasons in physiological characteristics and grain yield of common bean of early cycle. Two experiments were conducted in the field, the first in winter season and the second in wet season. The experimental design was a randomized complete block design, consisting of five and seven low doses of glyphosate and one period of application, with four replications. Glyphosate low dose of 108.0 g a.e. ha-1 impaired net CO2 assimilation rate, stomatal conductance, transpiration rate, instantaneous carboxylation efficiency, number of pods per plant, number of grains per plant and number of grains per pod. Glyphosate dose of 7.2 g a.e. ha-1 provided a 23% increase in grain yield in winter season, and the dose of 36.0 g a.e. ha-1 provided a 109% increase in grain yield in wet season. To our knowledge, this is the first report on effect of glyphosate at low doses and sowing season to obtain yield increases in common bean of early cycle.

Rapid, sensitive and selective detection of glyphosate in wheat and rice flour using a polar stationary phase by LC-MS/MS

Rapid, sensitive and selective method was studied for the determination of glyphosate in rice and wheat flour using a Raptor Polar column. Samples were extracted with acidified methanol solution. Isotope labeled internal standard was added with the extraction solvent to ensure accurate tracking and quantitation. The glyphosate was analyzed by liquid chromatography tandem mass spectrometry using a Raptor Polar column. Method performance was evaluated through a series of parameters that include accuracy, precision, linearity, limit of detection (LOD), limit of quantitation (LOQ) and matrix effect. Mean recoveries for all matrices were within 96-116% at three fortification levels. Precision for replicates was ≤19% relative standard deviation (RSD%) for wheat and ≤9% RSD% for rice across all fortification levels. Linearity was good for both matrices with a correlation coefficient >0.999 and residual <20% in the concentration range 0.025-1 mg kg-1. LOD was 0.005 mg kg-1for both rice and wheat flour and the LOQ was 0.05 mg kg-1for both matrices. The matrix effect was also studied. A successful method for the analysis of glyphosate in wheat and rice flour assure that the criteria of acceptability of the maximum residue levels (MRLs) are insured.

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.

Glyphosate Use, Toxicity and Occurrence in Food

Glyphosate is a systemic, broad-spectrum and post-emergent herbicide. The use of glyphosate has grown in the last decades, and it is currently the most used herbicide worldwide. The rise of glyphosate consumption over the years also brought an increased concern about its possible toxicity and consequences for human health. However, a scientific community consensus does not exist at the present time, and glyphosate’s safety and health consequences are controversial. Since glyphosate is mainly applied in fields and can persist several months in the soil, concerns have been raised about the impact that its presence in food can cause in humans. Therefore, this work aims to review the glyphosate use, toxicity and occurrence in diverse food samples, which, in certain cases, occurs at violative levels. The incidence of glyphosate at levels above those legally allowed and the suspected toxic effects of this compound raise awareness regarding public health.

Glyphosate Herbicide: Reproductive Outcomes and Multigenerational Effects

Glyphosate base herbicides (GBHs) are the most widely applied pesticides in the world and are mainly used in association with GBH-tolerant crop varieties. Indiscriminate and negligent use of GBHs has promoted the emergence of glyphosate resistant weeds, and consequently the rise in the use of these herbicides. Glyphosate, the active ingredient of all GBHs, is combined with other chemicals known as co-formulants that enhance the herbicide action. Nowadays, the safety of glyphosate and its formulations remain to be a controversial issue, as evidence is not conclusive whether the adverse effects are caused by GBH or glyphosate, and little is known about the contribution of co-formulants to the toxicity of herbicides. Currently, alarmingly increased levels of glyphosate have been detected in different environmental matrixes and in foodstuff, becoming an issue of social concern. Some in vitro and in vivo studies have shown that glyphosate and its formulations exhibit estrogen-like properties, and growing evidence has indicated they may disrupt normal endocrine function, with adverse consequences for reproductive health. Moreover, multigenerational effects have been reported and epigenetic mechanisms have been proved to be involved in the alterations induced by the herbicide. In this review, we provide an overview of: i) the routes and levels of human exposure to GBHs, ii) the potential estrogenic effects of glyphosate and GBHs in cell culture and animal models, iii) their long-term effects on female fertility and mechanisms of action, and iv) the consequences on health of successive generations.

Epigenetic Changes Associated With Exposure to Glyphosate-Based Herbicides in Mammals

Glyphosate is a phosphonomethyl amino acid derivative present in a number of non-selective and systemic herbicides. During the last years the use of glyphosate-based herbicide (GBH) has been increasing exponentially around the world, including Argentina. This fact added to the detection of glyphosate, and its main metabolite, amino methylphosphonic acid (AMPA), in environmental matrices such as soil, sediments, and food, has generated great concern about its risks for humans, animals, and environment. During the last years, there were controversy and intense debate regarding the toxicological effects of these compounds associated with the endocrine system, cancer, reproduction, and development. The mechanisms of action of GBH and their metabolites are still under investigation, although recent findings have shown that they could comprise epigenetic modifications. These are reversible mechanisms linked to tissue-specific silencing of gene expression, genomic imprinting, and tumor growth. Particularly, glyphosate, GBH, and AMPA have been reported to produce changes in global DNA methylation, methylation of specific genes, histone modification, and differential expression of non-coding RNAs in human cells and rodents. Importantly, the epigenome could be heritable and could lead to disease long after the exposure has ended. This mini-review summarizes the epigenetic changes produced by glyphosate, GBHs, and AMPA in humans and rodents and proposes it as a potential mechanism of action through which these chemical compounds could alter body functions.

Determination of glyphosate and AMPA in oat products for the selection of candidate reference materials

The use of reference materials (RMs) is critical for validating and testing the accuracy of analytical protocols. The National Institute of Standards and Technology (NIST) is in initial stages of developing a glyphosate in oats RM. The first aim of this study was to optimize and validate a robust method for the extraction and analysis of glyphosate and aminomethylphosphonic acid (AMPA). The optimized method was used to screen thirteen commercially available oat products to identify candidate RMs. Glyphosate was detected in all samples, with the highest glyphosate mass fraction of 1100 ng/g; lower levels were measured in grains from organic agriculture. AMPA was quantified in nine samples up to 40 ng/g. The findings of this study led to the identification of candidate RMs, with "high" and "low" glyphosate levels. A preliminary stability study determined that glyphosate is stable in oat material at room temperature for six months.

Low-dose exposure of glyphosate-based herbicides disrupt the urine metabolome and its interaction with gut microbiota

Glyphosate-based herbicides (GBHs) can disrupt the host microbiota and influence human health. In this study, we explored the potential effects of GBHs on urinary metabolites and their interactions with gut microbiome using a rodent model. Glyphosate and Roundup (equal molar for glyphosate) were administered at the USA glyphosate ADI guideline (1.75 mg/kg bw/day) to the dams and their pups. The urine metabolites were profiled using non-targeted liquid chromatography-high resolution mass spectrometry (LC-HRMS). Our results found that overall urine metabolite profiles significantly differed between dams and pups and between female and male pups. Specifically, we identified a significant increase of homocysteine, a known risk factor of cardiovascular disease in both Roundup and glyphosate exposed pups, but in males only. Correlation network analysis between gut microbiome and urine metabolome pointed to Prevotella to be negatively correlated with the level of homocysteine. Our study provides initial evidence that exposures to commonly used GBH, at a currently acceptable human exposure dose, is capable of modifying urine metabolites in both rat adults and pups. The link between Prevotella-homocysteine suggests the potential role of GBHs in modifying the susceptibility of homocysteine, which is a metabolite that has been dysregulated in related diseases like cardiovascular disease or inflammation, through commensal microbiome.

Effects of glyphosate exposure on human health: Insights from epidemiological and in vitro studies

Glyphosate (GLY) is a broad-spectrum, post-emergent, non-selective and synthetic universal herbicide, whose commercial formulations are referred to as glyphosate-based-herbicides (GBHs). These chemicals and their metabolites can be found in soil, air, water, as well as groundwater and food products. This review summarizes to summarize current in vitro and epidemiological studies investigating the effects of GLY exposure on human health. Recent human cell studies have reported several GLY and GBH toxicological effects and have contributed to a better understanding of the deleterious consequences associated with their exposure. However, these detrimental effects are dependent on the cell type, chemical composition, as well as magnitude and time of exposure, among other factors. Moreover, the deleterious effects of GLY exposure on human health were observed in epidemiological studies; however, most of these studies have not determined the GLY dosage to confirm a direct effect. While GLY toxicity is clear in human cells, epidemiological studies investigating individuals exposed to different levels of GLY have reported contradictory data. Therefore, based on currently available in vitro and epidemiological data, it is not possible to confirm the complete safety of GLY use, which will require additional comprehensive studies in animal models and humans.

Robust and highly sensitive micro liquid chromatography-tandem mass spectrometry method for analyses of polar pesticides (glyphosate, aminomethylphosfonic acid, N-acetyl glyphosate and N-acetyl aminomethylphosfonic acid) in multiple biological matrices

Glyphosate is the most used herbicide in agriculture. To monitor glyphosate exposure, analytical methods have to fulfill requirements with regard to sensitivity, reproducibility, ease of handling/high-throughput and applicability to multiple biological matrices. Furthermore, the methods have to include the degradation product of glyphosate, aminomethylphosfonic acid (AMPA) and preferably metabolites of glyphosate and AMPA, N-acetyl AMPA and N-acetyl glyphosate. Majority of the published methods for glyphosate and AMPA require derivatization to be able to achieve high sensitivity. In this work, we present highly sensitive microLC-MS/MS method for simultaneous quantification of glyphosate, AMPA, N-acetyl AMPA and N-acetyl glyphosate in multiple biological matrices without derivatization. The combination of simple sample clean-up procedures for simultaneous handling of 96 sample and short chromatographic run of only 3.4 min, meets the requirements for high-throughput methods. Simple mobile phase of water containing formic and medronic acids and isocratic run provided robust chromatographic separation on hypercarb column. The use of micro-flow system decreased the background noise, increasing the sensitivity. Achieved Low Limits of Quantification (LOQs) for liquid samples (plasma/serum/urine) were 0.00005 mg L-1 and 0.0001 mg kg-1 for solid samples (grain and soybean based feed/stomach/gizzard/intestinal content), which is more than 100 time more sensitive compared to QuPPe-Method. The method was validated in representative matrices with minimum of five fortification levels, six measurements per spiked concentration and three batches. All the samples were spiked with corresponding internal standards for all four analytes before sample clean-up procedures, ensuring high accuracy and precision. Recoveries for plasma/serum ranged between 86-108%, urine 93-120%, feed 91-115% and stomach/gizzard/intestinal content 92-110% with precision below 20%. The method's applicability was tested on 2000 samples measured during one year period.

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.

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.

Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence

Glyphosate is the most widely used broad-spectrum systemic herbicide in the world. Recent evaluations of the carcinogenic potential of glyphosate-based herbicides (GBHs) by various regional, national, and international agencies have engendered controversy. We investigated whether there was an association between high cumulative exposures to GBHs and increased risk of non-Hodgkin lymphoma (NHL) in humans. We conducted a new meta-analysis that includes the most recent update of the Agricultural Health Study (AHS) cohort published in 2018 along with five case-control studies. Using the highest exposure groups when available in each study, we report the overall meta-relative risk (meta-RR) of NHL in GBH-exposed individuals was increased by 41% (meta-RR = 1.41, 95% confidence interval, CI: 1.13-1.75). For comparison, we also performed a secondary meta-analysis using high-exposure groups with the earlier AHS (2005), and we calculated a meta-RR for NHL of 1.45 (95% CI: 1.11-1.91), which was higher than the meta-RRs reported previously. Multiple sensitivity tests conducted to assess the validity of our findings did not reveal meaningful differences from our primary estimated meta-RR. To contextualize our findings of an increased NHL risk in individuals with high GBH exposure, we reviewed publicly available animal and mechanistic studies related to lymphoma. We documented further support from studies of malignant lymphoma incidence in mice treated with pure glyphosate, as well as potential links between glyphosate / GBH exposure and immunosuppression, endocrine disruption, and genetic alterations that are commonly associated with NHL or lymphomagenesis. Overall, in accordance with findings from experimental animal and mechanistic studies, our current meta-analysis of human epidemiological studies suggests a compelling link between exposures to GBHs and increased risk for NHL.

Occurrence of glyphosate in beer from the Latvian market

A sensitive LC-MS/MS method for the determination of glyphosate in beer has been developed, validated, and applied to analyse 100 beer samples from 24 different producers and distributors in Latvia. The selected samples represented most beer brands and varieties sold in local supermarkets. Different procedures for sample preparation and chromatographic separation were compared. The final version of the method consisted of solid phase extraction, chromatographic separation on aminopropyl stationary phase, and detection using tandem mass spectrometry. The concentration of glyphosate in beer varied from below the LOD of 0.2 μg kg-1 up to 150 μg kg-1, higher than previously reported. Significantly higher (p < 0.01) content of glyphosate was observed in beers that did not have the country of production disclosed on the label and were sold in local supermarkets by distributors from Latvia (1.8 μg kg-1 median concentration in locally produced beer, 6.7 μg kg-1 in beer of undisclosed origin).

The Ramazzini Institute 13-week study on glyphosate-based herbicides at human-equivalent dose in Sprague Dawley rats: study design and first in-life endpoints evaluation

BACKGROUND

Glyphosate-based herbicides (GBHs) are the most widely used pesticides worldwide, and glyphosate is the active ingredient of such herbicides, including the formulation known as Roundup. The massive and increasing use of GBHs results in not only the global burden of occupational exposures, but also increased exposure to the general population. The current pilot study represents the first phase of a long-term investigation of GBHs that we are conducting over the next 5 years. In this paper, we present the study design, the first evaluation of in vivo parameters and the determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) in urine.

METHODS

We exposed Sprague-Dawley (SD) rats orally via drinking water to a dose of glyphosate equivalent to the United States Acceptable Daily Intake (US ADI) of 1.75 mg/kg bw/day, defined as the chronic Reference Dose (cRfD) determined by the US EPA, starting from prenatal life, i.e. gestational day (GD) 6 of their mothers. One cohort was continuously dosed until sexual maturity (6-week cohort) and another cohort was continuously dosed until adulthood (13-week cohort). Here we present data on general toxicity and urinary concentrations of glyphosate and its major metabolite AMPA.

RESULTS

Survival, body weight, food and water consumption of the animals were not affected by the treatment with either glyphosate or Roundup. The concentration of both glyphosate and AMPA detected in the urine of SD rats treated with glyphosate were comparable to that observed in animals treated with Roundup, with an increase in relation to the duration of treatment. The majority of glyphosate was excreted unchanged. Urinary levels of the parent compound, glyphosate, were around 100-fold higher than the level of its metabolite, AMPA.

CONCLUSIONS

Glyphosate concentrations in urine showed that most part of the administered dose was excreted as unchanged parent compound upon glyphosate and Roundup exposure, with an increasing pattern of glyphosate excreted in urine in relation to the duration of treatment. The adjuvants and the other substances present in Roundup did not seem to exert a major effect on the absorption and excretion of glyphosate. Our results demonstrate that urinary glyphosate is a more relevant marker of exposure than AMPA in the rodent model.

Development and Validation of Ion Chromatography-Tandem Mass Spectrometry-Based Method for the Multiresidue Determination of Polar Ionic Pesticides in Food

An extraction method using acidified methanol based on the quick polar pesticide (QuPPe) method using suppressed ion chromatography coupled to mass spectrometry was developed and validated for the direct analysis of polar pesticides, without the need for derivatization or ion pairing, in cereals and grapes. The method was robust, and results for glyphosate, aminomethyl phosphonic acid (AMPA), N-acetyl-AMPA, glufosinate, 3-methylphosphinicopropionic acid (3-MPPA), N-acetyl glufosinate, ethephon, chlorate, perchlorate, fosetyl aluminum, and phosphonic acid at three concentration levels (typically 0.01, 0.05, and 0.1 mg/kg) were compliant with SANTE/11945/2015 guideline method performance criteria. Cereal-based infant food proved to be a more challenging matrix and validated only for glyphosate, chlorate, and perchlorate at 0.005, 0.01, and 0.05 mg/kg. The developed method enables the multiresidue analysis of 12 ionic pesticides and relevant metabolites in a single analysis. Until now, the analysis of these compounds required several different single-residue methods using different chromatographic conditions. This multiresidue approach offers the possibility of more cost-effective and more efficient monitoring of polar ionic pesticides and contaminants that are of concern to food regulation bodies and consumers.

Direct and sensitive determination of glyphosate and aminomethylphosphonic acid in environmental water samples by high performance liquid chromatography coupled to electrospray tandem mass spectrometry

A novel method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed for the sensitive determination of glyphosate and its major degradation product, AMPA in environmental water samples. The method involves the use of MS compatible mobile phases (0.1% formic acid in water and acetonitrile) for HPLC and direct analysis of water samples without sample derivatization. The method has been validated in different types of water matrices (drinking, surface and groundwater) by accuracy and precision studies with samples spiked at 0.1, 7.5 and 90 ppb. All mean accuracy values ranged from 85% to 112% for glyphosate and AMPA using both primary and secondary quantitative ion transitions (RSD ≤ 10%). Moreover, both primary and secondary ion transitions for glyphosate and AMPA can achieve the quantitation limits at 0.1 ppb. The linear dynamic range of the calibration curves were from 0.1 to 100 ppb for each analyte at each ion transitions with correlation coefficient higher than 0.997.

Analysis of glyphosate and aminomethylphosphonic acid in water, plant materials and soil

There is a need for simple, fast, efficient and sensitive methods of analysis for glyphosate and its degradate aminomethylphosphonic acid (AMPA) in diverse matrices such as water, plant materials and soil to facilitate environmental research needed to address the continuing concerns related to increasing glyphosate use. A variety of water-based solutions have been used to extract the chemicals from different matrices. Many methods require extensive sample preparation, including derivatization and clean-up, prior to analysis by a variety of detection techniques. This review summarizes methods used during the past 15 years for analysis of glyphosate and AMPA in water, plant materials and soil. The simplest methods use aqueous extraction of glyphosate and AMPA from plant materials and soil, no derivatization, solid-phase extraction (SPE) columns for clean-up, guard columns for separation and confirmation of the analytes by mass spectrometry and quantitation using isotope-labeled internal standards. They have levels of detection (LODs) below the regulatory limits in North America. These methods are discussed in more detail in the review.

Analysis of glyphosate and aminomethylphosphonic acid in leaves from Coffea arabica using high performance liquid chromatography with quadrupole mass spectrometry detection

Glyphosate is a commonly applied herbicide in coffee plantations. Because of its non-selective mode of action it can damage the crop exposed through spray drift. Therefore, it is of interest to study glyphosate fate in coffee plants. The aim of this study was to develop an analytical method for accurate and precise quantification of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) at trace levels in coffee leaves using liquid chromatography with single-quadrupole mass spectrometry detection. The method is based on a two-step solid phase extraction (SPE) with an intermediate derivatization reaction using 9-fluorenylmethylchloroformate (FMOC). An isotope dilution method was used to account for matrix effects and to enhance the confidence in analyte identification. The limit of quantification (LOQ) for glyphosate and AMPA in coffee leaves was 41 and 111 μg kg(-1) dry weight, respectively. For the method optimization a design of experiments (DOE) approach was used. The sample clean-up procedure can be simplified for the analysis of less challenging matrices, for laboratories having a tandem mass spectrometry detector and for cases in which quantification limits above 0.1 mg kg(-1) are acceptable, which is often the case for glyphosate. The method is robust, possesses high identification confidence, while being suitable for most commercial and academic laboratories. All leaf samples from five coffee fields analyzed (n=21) contained glyphosate, while AMPA was absent. The simplified clean-up procedure was successfully validated for coffee leaves, rice, black beans and river water.

Analysis of Glyphosate and Aminomethylphosphonic Acid in Nutritional Ingredients and Milk by Derivatization with Fluorenylmethyloxycarbonyl Chloride and Liquid Chromatography-Mass Spectrometry

A straightforward analytical method based on derivatization with fluorenylmethyloxycarbonyl chloride and liquid chromatography-mass spectrometry has been developed for the analysis of residues of glyphosate and aminomethylphosphonic acid (AMPA) in a suite of nutritional ingredients derived from soybean, corn, and sugar beet and also in cow's milk and human breast milk. Accuracy and intermediate precision were 91-116% and <10% RSD, respectively, in soy protein isolate. Limits of quantitation were 0.05 and 0.005 μg/g in powdered and liquid samples, respectively. Glyphosate and AMPA were quantified at 0.105 and 0.210 μg/g (soy protein isolate) and 0.850 and 2.71 μg/g (soy protein concentrate, both derived from genetically modified soybean), respectively. Residues were not detected in soy milk, soybean oil, corn oil, maltodextrin, sucrose, cow's milk, whole milk powder, or human breast milk. The method is proposed as a convenient tool for the survey of glyphosate and AMPA in the ingredient supply chain.

Direct liquid chromatography-tandem mass spectrometry determination of underivatized glyphosate in rice, maize and soybean

The residue determination of the widely used herbicide glyphosate (GLY) is highly problematic due to its amphoteric character, low mass and lack of chemical groups that might facilitate its detection. Most methods developed up to now have employed pre-column or post-column derivatization to form fluorescent derivatives and/or to reduce the polar character of the analyte facilitating its chromatographic retention. The aim of this work is to evaluate the feasibility of performing the direct LC-MS/MS determination of GLY residues in vegetables. After testing several Hydrophilic Interaction Liquid Chromatography (HILIC) columns, Obelisc N was selected due to its better chromatographic retention. LC-MS/MS determination has been performed in negative ionization mode, monitoring up to four transitions to give high reliability to the identification/confirmation process. This approach has been evaluated for the determination of GLY residues in rice, maize and soybean samples, and the method validated at different concentrations in compliance with the maximum residue limits established in the current legislation. After sample extraction with water, a combination of extract dilution, partition with dichloromethane, and solid phase extraction (SPE) using Oasis HLB cartridges (depending on the sample matrix under analysis) was applied. Quantification was made by using isotope-labeled GLY as internal standard and calibration in solvent. The methodology developed allows the rapid determination of GLY residues avoiding the derivatization step typically applied for this herbicide. The most critical issue is the robustness of the Obelisc N column, which was found to suffer rapid degradation with time. Extreme care and continuous testing of retention times and peak shapes is required for a reliable determination.

Direct determination of glyphosate and its major metabolite, aminomethylphosphonic acid, in fruits and vegetables by mixed-mode hydrophilic interaction/weak anion-exchange liquid chromatography coupled with electrospray tandem mass spectrometry

A novel method was developed for the direct, sensitive, and rapid determination of glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA), in fruit and vegetable samples by mixed-mode hydrophilic interaction/weak anion-exchange liquid chromatography (HILIC/WAX) coupled with electrospray tandem mass spectrometry (ESI-MS/MS). Homogenized samples were extracted with water, without derivatization or further clean-up, and the extracts were injected directly onto the Asahipak NH2P-50 4E column (250 mm × 4.6 mm i.d., 5 μm). The best results were obtained when the column was operated under mixed-mode HILIC/WAX elution conditions. An initial 10-min washing step with acetonitrile/water (10:90, v/v) in HILIC mode was used to remove potentially interfering compounds, and then the analytes were eluted in WAX mode with acetonitrile and water containing 0.1 molL(-1) ammonium hydroxide under gradient elution for the ESI analysis in negative ion mode. Limits of quantification of glyphosate and AMPA were 5 μgkg(-1) and 50 μgkg(-1), respectively, with limits of detection as low as 1.2 μgkg(-1) for glyphosate and 15 μgkg(-1) for AMPA. The linearity was satisfactory, with correlation coefficients (r)>0.9966. Recovery studies were carried out on spiked matrices (6 vegetables, 3 fruits) with glyphosate at four concentrations and AMPA at three concentrations. The mean recoveries for glyphosate and AMPA were 75.3-110% and 76.1-110%, respectively, with relative standard deviations in the range of 1.1-13.8%. The intra-day precision (n=7) for glyphosate and AMPA in vegetable and fruit samples spiked at an intermediate level between 5.9% and 7.5%, and the inter-day precision over 11 days (n=11) was between 7.0% and 13%.

Development and application of a liquid chromatography-mass spectrometry method to evaluate the glyphosate and aminomethylphosphonic acid dissipation in maize plants after foliar treatment

A simple and fast method has been developed and validated to measure glyphosate (GLYP) and aminomethylphosphonic acid (AMPA), which were previously derivatized with 9-fluorenylmethylchloroformate (FMOC-Cl), in maize plants using liquid chromatography (LC) coupled to fluorescence (FLD) and electrospray ionization mass spectrometry (ESI-MS) detection. The method has shown to be consistent, reliable, precise, and efficient. Moreover, the limits of detection (LOD) and quantification (LOQ) reached with the proposed method for GLYP and AMPA are lower than the established maximum residue levels (MRLs). The validated method was applied to quantify GLYP and AMPA in genetically modified (GM) maize foliar treated with the herbicide. It has been found that the GLYP dissipation was mainly due to the progressive dilution effect after herbicide treatment. Finally, it was also observed that the GLYP residue dissipation trend in maize shoot (leaves and stem) tissue determined by LC-ESI-MS matched that determined by liquid scintillation.

Study of liquid chromatography/electrospray ionization mass spectrometry matrix effect on the example of glyphosate analysis from cereals

Glyphosate is one of the most common pesticides used in the pre-harvest treatment of cereals. This paper examines the matrix effect of glyphosate liquid chromatography/electrospray ionization mass spectrometric (LC/ESI-MS) analysis in wheat and rye. The matrix effect (ionization suppression) was found to be dependent on sample particle size taken for the extraction. If samples are ground to very small particles severe ionization suppression occurs. For lower glyphosate contents (<1 mg/kg) the signal may even be suppressed by more than 90%. The matrix effect was found to be dependent on the matrix - rye showed significantly stronger ionization suppression than wheat, although these matrices are not very different. The matrix effect also depends on the concentration of glyphosate in the post-extraction spiked samples. It is demonstrated that the isotope-labelled standard (13)C(2)-glyphosate undergoes different ionization suppression than glyphosate and is therefore not efficient in compensating for matrix effect. At the same time the extrapolative dilution approach allows to efficiently compensate for matrix effect.

[Determination of glyphosate and aminomethylphosphonic acid in rice using liquid chromatography-tandem mass spectrometry]

A method was developed for the determination of glyphosate (GLY) and aminomethylphosphonic acid (AMPA) in rice using liquid chromatography tandem mass spectrometry (LC-MS/MS). The sample was extracted with water followed by a simple cleanup with a C18 solid phase extraction (SPE) cartridge, and then GLY and AMPA were derivatized using 9-fluorenylmethoxycarbonyl (FMOC-Cl) in borate buffer. The derivatives of GLY and AMPA were separated on a C18 column with gradient elution with the mobile phase of acetonitrile and 5 mmol/L ammonium acetate (pH 9), and finally detected with negative ion electrospray ionization-mass spectrometry (ESI-MS) in multiple reaction monitoring (MRM) mode. The results showed that the linearities of GLY and AMPA were in the concentration range of 0.000 50 to 1.0 mg/L with the correlation coefficients of 0.999 7 and 0.999 9, respectively. The mean spiked recoveries of GLY and AMPA at 3 spiked levels ranged from 72.5% to 113.6% with the relative standard deviations (RSD, n = 5) of 3.8% - 16.2%. The limits of detection were 2.0 and 3.0 microg/kg for GLY and AMPA, respectively. This method is rapid, sensitive, and suitable for simultaneous determination of GLY and AMPA in rice.