Optimization and validation of a liquid chromatography-tandem mass spectrometry method for the determination of glyphosate in human urine after pre-column derivatization with 9-fluorenylmethoxycarbonyl chloride

Low-background interference detection of glyphosate, glufosinate, and AMPA in foods using UPLC-MS/MS without derivatization

The abuse of herbicides has emerged as a great threat to food security. Herein, a low-background interference detection method based on UPLC-MS was developed for the simultaneous determination of glufosinate, glyphosate, and its metabolite aminomethylphosphonic acid (AMPA) in foods. Initially, this study proposed a simple and rapid pretreatment method, utilizing water extraction and PRiME HLB purification to isolate glyphosate, glufosinate, and AMPA from food samples. After the optimization of pretreatment conditions, the processed samples are then analyzed directly by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) without pre-column derivatization. The method can effectively reduce interference from by-products of pre-column derivatization and background substrates of food sample, showing low matrix effects (ME) ranging from - 24.83 to 32.10%. Subsequently, the method has been validated by 13 kinds of food samples. The recoveries of the three herbicides in the food samples range from 84.2 to 115.6%. The limit of detection (LOD) is lower to 0.073 mg/kg, 0.017 mg/kg, and 0.037 mg/kg, respectively. Moreover, the method shows an excellent reproducibility with relative standard deviations (RSD) within 16.9%. Thus, the method can provide high trueness, reproducibility, sensitivity, and interference-free detection to ensure human health safety.

First Report of the Joint Exposure to Glyphosate and Glufosinate of a Male Population in the Province of Córdoba (Argentina)

Despite potential health implications, data on the presence of Glyphosate (GLY) and other non-GLY herbicides in human matrices remain scarce. This study aimed to develop a simple and cost-effective methodology for detecting and quantifying GLY, its primary biodegradation product; aminomethylphosphonic acid (AMPA); and glufosinate (GLU) in plasma and urine of environmentally and occupationally exposed populations from the province of Córdoba (Argentina). Different alternatives of pre-treatment, derivatization with FMOC-Cl, solid phase extraction, and final sample conditioning steps were evaluated to improve the quantification of the herbicides by a high-performance liquid chromatography system coupled to a triple-quadrupole mass spectrometer. Recoveries ranged from 39 to 84% in both matrices, while limits of quantification were 3, 1, and 0.3 ng/mL and 3.6, 5.1, and 0.3 ng/mL for AMPA, GLY, and GLU in plasma and urine, respectively. In plasma samples, GLY was the most frequently detected analyte (32%), followed by GLU (10%). In urine samples, GLU was the most frequently detected herbicide (13%), followed by GLY (6%). No differences between group or matrix correlations were found. This study is the first report of GLU in human biological matrices and should be used to establish baseline values for future surveillance systems.

Advanced Liquid Chromatography with Tandem Mass Spectrometry Method for Quantifying Glyphosate, Glufosinate, and Aminomethylphosphonic Acid Using Pre-Column Derivatization

Analytical limitations make it challenging to develop effective methodologies for understanding glyphosate-based herbicide levels in drinking water and groundwater. Due to their lack of chromophores and zwitterionic nature, glyphosate-based herbicides are difficult to detect using traditional methods. This paper offers a straightforward method for quantifying glyphosate, glufosinate, and aminomethylphosphonic acid (AMPA) via 9-fluorenylmethylchloroformate (FMOC-Cl) pre-column derivatization and analysis by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Method development was focused on optimizing the critical variables for optimal derivatization using a 24-factorial design. We found that complete derivatization significantly depends on the inclusion of borate buffer to create the alkaline conditions necessary for aminolysis. Ethylenediaminetetraacetic acid (EDTA) addition was critical to minimize metallic chelation and ensure reproducible retention times and peaks. However, EDTA concentrations ≥5% decreased peak intensity due to ion suppression. The FMOC-Cl concentration and derivatization time exhibited a direct proportional relationship, with the complete reaction achieved with 2.5 mM FMOC-Cl after 4 h. Concentrations of FMOC-Cl greater than 2.5 mM led to the formation of oxides, which interfere with the detection sensitivity and selectivity. Desirable results were achieved with 1% EDTA, 5% borate, and 2.5 mM FMOC-Cl, which led to complete derivatization after 4 h.

An analytical method for the determination of glyphosate and aminomethylphosphoric acid using an anionic polar pesticide column and the application in urine and serum from glyphosate poisoning patients

An analytical method for the determination of glyphosate (GLY) and aminomethylphosphoric acid (AMPA) in biological fluid samples (serum and urine) from poisoning patients using liquid chromatography-tandem mass spectrometry (LC-MS/MS) is established. After the sample pretreatment, including protein precipitation and a modified liquid-liquid extraction method, the chromatographic separation was conducted on a trifunctional modified hydrophilic column. The mobile phases in the gradient program were 2.5% formic acid aqueous solution and acetonitrile. The multiple reaction monitoring (MRM) models and the isotope-labeled internal standards were used in the acquisition process. Good linearities and satisfying recovery rates were obtained in two sample matrices with good RSDs. The detection limits of GLY and AMPA were <2 μg L^-1, which were close to those obtained in our previous research. The established method was applied to biological samples from five patients with glyphosate intoxication. The analysis of the trend for the concentration of GLY and AMPA in two biological samples was investigated, and the difference in the downward trend of AMPA in urine was found in patients with a relatively higher concentration of GLY in serum.

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.

Aptamer Trimode Biosensor for Trace Glyphosate Based on FeMOF Catalytic Oxidation of Tetramethylbenzidine

The stable and highly catalytic Fe metal-organic framework (FeMOF) nanosol was prepared and characterized by electron microscopy, and energy and molecular spectral analysis. It was found that FeMOF strongly catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H₂O₂ to produce TMBox, which had a fluorescence (FL) peak at 410 nm. When silver nanoparticles were added, it exhibited strong resonance Rayleigh scattering (RRS) activity and surface-enhanced Raman scattering (SERS) effect. This new FeMOF nanocatalytic trimode indicator reaction was combined with the glyphosate aptamer reaction to establish a new SERS/RRS/FL trimode biosensor for glyphosate. The sensor can be used for the analysis of environmental wastewater, and a new method for detecting glyphosate content in wastewater is proposed. The linear range of the sensor is 0.1-14 nmol/L, the detection limit is 0.05 nmol/L, the recovery is 92.1-97.5%, and the relative standard deviation is 3.6-8.7%.

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.

Validation of exposure indexes to pesticides through the analysis of exposure and effect biomarkers in ground pesticide applicators from Argentina

The characterization of the population exposed to pesticides and the use of effective biomarkers to evaluate potential health effects are determinant to identify vulnerable groups, understanding the causality of diverse pathologies and propose prevention policies. This is particularly important in countries where intensive agricultural practices had an explosive expansion in last decades. The aim of this study was assessing the usefulness of two exposure indexes questionnaire-based: Intensity Level of the pesticide Exposure (ILE) and Cumulative Exposure Index (CEI) and their scales, in terrestrial applicators of pesticide from the Province of Córdoba (Argentina). The analysis was performed contrasting ILE and CEI results with perceived symptomatology, in addition to effect and exposure biomarkers. A cross-sectional study was designed to compare pesticides body burdens and effect biomarkers between subjects occupationally (OE) and non-occupationally exposed (NOE) to pesticides. Prevalence of perceived symptomatology and genotoxicity damage was higher in the OE group. The exposure condition was the only variable explaining these differences. Significant associations were found between CEI and neurologic symptomatology (p < 0.05) and between ILE and plasmatic cholinesterase (p < 0.1). However, residues of HCB, β-HCH, α-endosulfan, pp'DDE, endrin, β-endosulfan, pp'DDT, endosulfan sulfate and mirex were found in blood samples from both groups. To our knowledge, this is the first report on pesticides body burdens in occupational exposure settings in Argentina. So far, our current results indicate that the occupational condition affects the health of the workers. Significant associations found between symptomatology and biomarkers with scales of CEI and ILE suggest their usefulness to verify different levels of exposure. Further research is necessary to propose these indexes as an affordable tool for occupational health surveillance in areas with difficult access to health care centres.