Method For Determination Of Glyphosate Research Articles

Nonderivatization method for determination of glyphosate, glufosinate, bialaphos, and their main metabolites in environmental waters based on magnetic metal-organic framework pretreatment.

A novel magnetic metal-organic framework composite was prepared by a self-assembly approach. The material properties were characterized by Fourier-transform infrared spectroscopy, vibrating sample magnetometry, thermogravimetry and differential thermogravimetric analysis, and X-photoelectron spectroscopy. Then, the as-prepared material was used as an adsorbent and indicated great enrichment ability toward glyphosate, glufosinate, bialaphos, and their main metabolites aminomethylphosphonic acid and 3-methylphosphinicopropionic acid. Based on this, an efficient magnetic solid-phase extraction method combined with ultra high performance liquid chromatography with high-resolution mass spectrometry for the pretreatment and determination of five target compounds in environmental waters was established. Parameters that could impact on the adsorption performance had been studied in detail. The proposed method was successfully applied for the simultaneous determination of glyphosate, glufosinate, bialaphos, and their main metabolites aminomethylphosphonic acid and 3-methylphosphinicopropionic acid in environmental water with recoveries in range of 86.2-104.6% with relative standard deviations less than 10%. Desired linearity was achieved varying from 1 to 100μg/L for five target analytes, respectively. The limits of detection were between 0.01 and 0.03μg/L.

HPLC Determination of Glyphosate, Aminomethylphosphonic Acid, and Glufosinate Using a Hypercarb Porous Graphite Adsorbent

A method for the HPLC determination of glyphosate, aminomethylphosphonic acid, and glufosinate using the gradient separation of analytes on a Hypercarb porous graphitized carbon adsorbent and an aqueous solution of ammonium formate and ammonia as a mobile phase is proposed. Analytes are detected using quadrupole and three-quadrupole mass spectrometers. In order to increase the retention of the analytes, the chromatographic column is washed with water before the injection of a sample solution. This procedure results in a three- to fourfold increase in the retention factors of the analytes in comparison with the analogues described in the publications.

Determination of glyphosate in surface water with high organic matter content

In this paper, we investigate the sample preparation and analysis process in order to achieve adequate results for surface water collected from rivers that flow through swamps and are consequently rich in organic matter. We show that matrix effects in glyphosate determination can be reduced by optimizing sample volume, liquid chromatography (LC) mobile phase buffer concentration and pH as well as gradient speed. Also, aspects of derivatization procedure (borate buffer concentration, fluorenylmethyloxycarbonyl chloride concentration) and their influence on accuracy are considered in detail. We encountered a cross-talk effect in the mass spectra, interfering with quantization during analysis, which was removed by optimizing MS parameters. As a result it was demonstrated that isotope-labelled internal standard with just one 13C atom is sufficient for the analysis.All these aspects were found to strongly impact the accuracy of the glyphosate determination but have received little or no attention in earlier works. We propose a reliable solid phase extraction and LC/ESI/MS/MS method for determination of glyphosate in organic-rich waters and demonstrate that LoD can be decreased by about two times using an ESI nebulizer with a modified design.

Development of simple and sensitive HPLC method for determination of glyphosate residues in soybean

The purpose of this study was to develop a simple and sensitive high performance liquid chromatography (HPLC) method for determination of glyphosate (GP) residues in soybean grains. From soybean matrix, glyphosate was extracted with a mixture of water and methanol (4:1, v/v) from soybean samples followed by protein precipitation with equal volume of methanol. No preconcentration and further clean up of the sample were required. Pre-column derivatization was carried out with excess amount of 9- fluorenylmethyl chloroformate (FMOC-Cl) in the presence of borate buffer. The gradient program developed in this method was successfully applied to a reverse phase HPLC system with a C18 column (ACE 5 μm 4.6 x 250 mm), and eluted with a mobile phase consisting of 50 mM phosphate buffer, pH 2.5, and acetonitrile at the flow rate of 0.8 ml/min and fluorescence detection. Parameters and conditions affecting extraction, derivatization reaction and chromatographic separation were systematically examined. Linearity of the method ranged from 0.005 - 1.0 μg/ml. The correlation coefficient (r2) of calibration curve for glyphosate in soybean sample was found to be 0.99929. The limit of detection (LOD) and limit of quantitation (LOQ) values were determined to be 0.125 mg/kg and 0.25 mg/kg, respectively. Average recovery was 95.2%. Repeatability and intermediate precision calculated on the basis of peak area were excellent and showed relative standard deviation ranged from 0.15 - 1.29% and 1.15 - 3.87%, respectively. The developed method has been successfully applied for determination of glyphosate residues in soybean grains obtained from Thailand and Nepal. Soybean samples (53) from two different lots were analyzed and glyphosate residues ranged from 0.23 mg/kg to 5.06 mg/kg. Almost 50% soybean samples contained nearly consistent residue levels in both lots but in remaining samples there was a significant variation of glyphosate levels between two lots. Relatively higher residues were detected in samples from Thailand (0.27-5.06 mg/kg) compared to Nepal (0.23-0.99 mg/kg). The results suggest that the proposed method can be used to determine glyphosate residues in foods derived from soybean and other crops such as corn, cotton, wheat, etc. where glyphosate is widely applied to these crops.

Rapid method for determination of glyphosate in groundwater using high performance liquid chromatography and solid-phase extraction after derivatization

The intensive use of pesticides in agriculture has prompted researchers to develop new methods for identifying these pollutants in water. This study sought to validate a high performance liquid chromatography (HPLC) method to determine the concentration of the pesticide glyphosate in groundwater samples by using solid-phase extraction (SPE) filters after derivatization with chloroformate 9-fluorenylmethoxycarbonyl (FMOC-Cl). For the HPLC method, we evaluated the following main validation parameters: linearity, specificity, precision, accuracy, robustness, and limits of detection and quantification. After validation of the method, we determined the concentration of glyphosate in samples from thirteen deep, tubular wells distributed in urban and rural areas in Chapeco, SC, Brazil. The solvent used in the extraction of excess FMOC-Cl was dichloromethane and subsequently filtration was performed on C18 SPE, and injected into the chromatograph column in amino polymer with fluorescence detection. The analytical curve made in ultrapure water was linear, with a correlation coefficient of 0.99. The limits of detection and quantification were 0.24 and 0.07 µg L-1, respectively. Recovery tests in natural waters ranged from 90.37 to 101.70%. Glyphosate was detected in 5 of the thirteen wells evaluated. The highest concentration of glyphosate (6.80 µg L-1) was detected in a countryside well, near the municipal water supply. Despite the low levels of glyphosate detected in our study, any amount present in groundwater samples is worrisome, as these molecules have low ground mobility.

Study on the method for determination of glyphosate in workplace air by HPLC post-column derivatization

目的 建立工作场所空气中草甘膦测定的柱后衍生-高效液相色谱法.方法 样品溶液中草甘膦通过液相色谱分离后,经柱后衍生仪与邻苯二甲醛(OPA)及巯基乙醇反应,形成具有极强荧光性的杂环化合物,使用荧光检测器检测,保留时间定性,峰面积定量.结果 草甘膦在0.05～2.00 mg/L范围内线性关系良好,相关系数为0.999 3;以3倍信噪比计算,该法的检出限为0.05 mg/L;若采集15L空气进行测定,最低检出浓度为3.4 mg/m3;0.1～0.5mg/L的草甘膦加标样品重复测定6次,相对标准偏差1.18％～5.02％,回收率为88.7％～98.9％.结论 该方法可用于工作场所空气中草甘膦含量的检测。

A sequential-injection reversed-phase chromatography method for fluorimetric determination of glyphosate and aminomethylphosphonic acid

Glyphosate (GLYPH) is one of the most used herbicides around the world. In soil and waters, GLYPH is metabolized into aminomethylphosphonic acid (AMPA). Because of their high water solubility and half-life, both GLYPH and AMPA have been detected long after application. The present paper describes the development of a low cost Sequential Injection Chromatography (SIC) method for determination of GLYPH and AMPA based on pre-column oxidation of GLYPH to glycine (GLY) by hypochlorite, exploiting the stopped flow approach, followed by reaction with the fluorogenic reagent o-phthaldialdehyde in the presence of 2-mercaptoethanol (OPA-2ME) in borate buffer (pH > 9) to produce the fluorescent 1-(2′-hydroxyethylthio)-2-N-alkylisoindole. While GLYPH is being converted into GLY, the determination of AMPA is made by pre-column derivatization with OPA-2ME. Isocratic elution of both GLYPH and AMPA derivatives was done using a mobile phase composed of 20:80 (v/v) methanol:10 mM phosphate buffer (pH 6.8) at a flow rate of 30 μL s−1. The proposed method solved the mutual fluorescence interference of AMPA and GLY derivatives, and the interference of humic substances. A linear response was observed for concentrations up to 5.0 μM for both compounds, with limits of detection and quantification of 0.11 and 0.35 μM (GLYPH), and 0.06 and 0.20 μM (AMPA), respectively. Application of the method to spiked natural waters gave recoveries between 78 and 134%, suggesting that the method has potential to be applied for water sampling trials.

A simple and green analytical method for determination of glyphosate in commercial formulations and water by diffuse reflectance spectroscopy

This article describes a simple, inexpensive, and environmentally friendly method for the monitoring of glyphosate using diffuse reflectance spectroscopy. The proposed method is based on reflectance measurements of the colored compound produced from the spot test reaction between glyphosate and p-dimethylaminocinnamaldehyde ( p-DAC) in acid medium, using a filter paper as solid support. Experimental designs were used to optimize the analytical conditions. All reflectance measurements were carried out at 495 nm. Under optimal conditions, the glyphosate calibration graphs obtained by plotting the optical density of the reflectance signal (A R) against the concentration were linear in the range 50–500 μg mL −1, with a correlation coefficient of 0.9987. The limit of detection (LOD) for glyphosate was 7.28 μg mL −1. The technique was successfully applied to the direct determination of glyphosate in commercial formulations, as well as in water samples (river water, pure water and mineral drinking water) after a previous clean-up or pre-concentration step. Recoveries were in the ranges 93.2–102.6% and 91.3–102.9% for the commercial formulations and water samples, respectively.

An alternative and fast method for determination of glyphosate and aminomethylphosphonic acid (AMPA) residues in soybean using liquid chromatography coupled with tandem mass spectrometry

A simple and specific method using reversed-phase liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was investigated, which allowed the determination of residues of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in soybean samples. An aqueous extraction with liquid-liquid partition followed by protein precipitation was performed before the LC/MS/MS determination. The quantitation of glyphosate and AMPA was performed in positive and negative ESI mode, respectively, using the multiple reaction monitoring (MRM) mode with three transitions for each analyte to enhance the specificity of the method and avoid false positives. The methodology reported in this work is capable of detecting residues of glyphosate and AMPA in soybean samples with limits of quantification of 0.30 and 0.34 mg kg(-1), respectively. This alternative method has throughput advantages such as simpler sample preparation and faster chromatographic analysis.

High-performance liquid chromatographic determination of glyphosate in water and plant material after pre-column derivatisation with 9-fluorenylmethyl chloroformate

This paper describes a robust and sensitive HPLC method for determination of glyphosate in water and plant material after pre-column derivatisation with 9-fluorenylmethyl chloroformate (FMOC-Cl) using single and coupled polymeric amino columns, respectively. New findings about optimisation of the derivatisation reaction and chromatographic behaviour of glyphosate and AMPA on polymeric amino column are also presented. The best HPLC conditions for the separation of glyphosate and AMPA in water samples were achieved using a single polymeric amino column and mobile phase at pH 10 which contained 55% (v/v) acetonitrile and 50 mM phosphate buffer. The method was validated by analysing 10 fortified rainwater samples at a level of 1 μg/l. The average recovery was 94% with relative standard deviation (R.S.D.) of 5.4% and the method detection limit of 0.16 μg/l. The HPLC separation of glyphosate (only) in plant material entailed the coupling of two polymeric amino columns via a switching valve to separate interfering products from the desired analyte. The method was validated using grass samples spiked at the level of 1 mg/kg and gave a method detection limit of 0.3 mg/kg for glyphosate and a recovery of 82.4% with R.S.D. of 10.3%.

Liquid Chromatographic Determination of Glyphosate and Aminomethylphosphonic Acid (AMPA) in Environmental Water: Collaborative Study

A new method for determination of glyphosate and aminomethylphosphonic acid (AMPA) residues in environmental water was collaboratively studied by 6 laboratories. The method is simpler and shorter than previous methods. A filtered volume of water is evaporated to dryness and the residue is dissolved in a buffered EDTA solution. Glyphosate and AMPA are determined by liquid chromatography with postcolumn reaction detection. The method was validated over the range 0.50-5000 ppb, although one of the collaborating laboratories could not reliably quantitate below 1.0 ppb. Statistical analysis of the results showed that typical reproducibility relative standard deviations (RSDR) ranged from 11 to 20% for both glyphosate and AMPA, which compares very well with predicted values for this concentration range. Total variability (as measured by sR) increased with increasing fortification level. The method has been adopted official first action by AOAC.

Improved Polarographic Method for Determination of Glyphosate Herbicide in Crops, Soil, and Water

A prior method for determination of glyphosate in water samples has been modified to accommodate samples of crops and soils. Differential pulse polarography as the determinative step enables analysis in an aqueous medium, which is important during extraction of this compound. Residues are cleaned up and concentrated by ion exchange on a strong basic resin in OH- form. The method is rapid, is applicable to a relatively broad selection of sample types, and gives recoveries consistently better than 60% with good precision. The main shortcoming of the method is that the limit of detection of 0.5-1.0 ppm may sometimes be inadequate. The metabolite, aminomethyl phosphonic acid, is not detected.