Computational design and synthesis of molecular imprinted polymers for selective solid phase extraction of sulfonylurea herbicides.

A high-efficiency approach for the synthesis of molecularly imprinted polymers has been developed and further for the solid-phase extraction of sulfonylurea herbicides in food samples. Molecular simulation approach combined chemometric selected metsulfuron-methyl (MSM) and 2-trifluoromethyl acrylic acid (TFMAA) as the template and the monomer to synthesize the molecularly imprinted polymers (MIPs). Experimental validation confirmed that the MSM-imprinted polymers showed a higher selectivity and affinity to sulfonylurea herbicides. The optimized molecularly imprinted solid-phase extraction (MISPE) conditions, including loading, washing, and eluting conditions, were established. The developed MISPE technology combined HPLC-MSMS was successfully used for the determination of sulfonylurea herbicides in foods. Compared with commercial SPE columns, MISPE showed high affinity, excellent selectivity and low matrix effect. The recoveries of sulfonylurea herbicides spiked in four matrices were between 86.4% and 100.2%, with the relative standard deviations (RSD) in the range of 0.9%-10.5%.

Preparation of molecularly imprinted polymer with class-specific recognition for determination of 29 sulfonylurea herbicides in agro-products.

Molecularly imprinting polymers with high selectivity toward 29 sulfonylurea herbicides were synthesized by precipitation polymerization, using metsulfuron-methyl and chlorsulfuron as the template molecule, 4-vinylpyridine as the function monomer, divinylbenzene as the crosslinking agent, and acetonitrile as porogen. The imprinted polymers were characterized and measured by scanning electron microscopy (SEM) and equilibrium adsorption experiments. The molecularly imprinted polymers displayed specific recognition for the tested 29 sulfonylurea herbicides, and the maximum apparent binding capacity was found to be 18.81 mg/g. The synthesized polymer was used as a solid-phase extraction (SPE) column coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of the tested analytes in agro-products. Within the range of 2-100 µg/L, the tested analytes have achieved a good linear association with correlation coefficient (R2) > 0.999. The calculated limits of detection (LODs, S/N=3) as along with limits of quantification (LOQs, S/N=10) were in the ranges of 0.005-0.07 µg/L and 0.018-0.23 µg/L, respectively. Under different spiking levels, the recovery rates were ranged from 74.8% - 110.5%, and the relative standard deviation (RSDs) were < 5.3%. Finally, the feasibility of the proposed methodology was successfully applied for detection of sulfonylurea herbicides in crops, vegetables, and oils samples.

Preparation of polydopamine-coated, graphene oxide/Fe3 O4 - imprinted nanoparticles for selective removal of sulfonylurea herbicides in cereals.

BACKGROUND: Sulfonylureas are potentially toxic broad-spectrum herbicides. They pose a persistent threat to food safety and the environment. It is therefore important to develop a rapid and efficient pretreatment and detection method to prevent their harmful effects on human health. RESULTS: In the present work, a novel and highly selective absorbent for chlorosulfuron (CS) detection was prepared by the simple self-polymerization of dopamine on the surface of magnetic graphene oxide using a CS template. The resultant imprinted nanoparticles (MGO@PDA-MIPs) were characterized by transmission electron microscopy, X-ray diffraction, vibrating-sample magnetometry, thermogravimetric analysis, and nitrogen adsorption-desorption. The adsorption experiments demonstrated that the MGO@PDA-MIPs have excellent selectivity with regard to CS, with a high imprinting factor of 3.41 compared with a non-imprinted polymer. The nanoparticles rapidly achieve adsorption equilibrium and efficient desorption because there are numerous binding sites on the thin polydopamine imprinting layer. Under optimized conditions, the MGO@PDA-MIPs can be used to detect sulfonylurea residues in cereal samples by magnetic solid phase extraction coupled with high performance liquid chromatography (HPLC). The nanoparticles have a satisfactory recovery rate (80.65-101.01%) with a relative standard deviation (RSD) of less than 7.15%, and a limit of detection with regard to CS of 1.61 µg kg-1 (S/N = 3). They can also be re-used at least seven times. CONCLUSION: The MGO@PDA-MIPs have outstanding recognition performance, and can be prepared by a facile, single-step, and environmentally friendly process. They therefore have excellent potential for the recognition and separation of trace sulfonylurea herbicides in complex matrices. © 2020 Society of Chemical Industry.

Preparation and comparison of Fe3O4@graphene oxide nanoclusters for analysis of glimepiride in urine by surface-assisted laser desorption/ionization time-of-flight mass spectrometry.

Graphene oxide (GO) has the ability to absorb certain compounds, and it can be modified with functional groups for different purposes; for instance, iron oxide (IO) nanoparticles can be used to concentrate analyte by a magnet. Recently, many kinds of GO have been developed, such as single-layer GO (SLGO), two-to-four layers of GO (i.e., few-layer GO, FLGO2-4), and four-to-eight layers of GO (i.e., multi-layer GO, MLGO4-8). However, the abilities of these layered GO coated with IO nanoparticles have not been investigated. In this study, we conducted a novel analysis of glimepiride by using layered GO-coated magnetic clusters of IO nanoparticles that were synthesized through a simple and facile emulsion-solvent evaporation method. The methodology is based on (i) enrichment of glimepiride using the layered GO-coated magnetic clusters of IO nanoparticles (IO@SLGO, IO@FLGO2-4, and IO@MLGO4-8), and (ii) rapid determination using magnetic cluster-based surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOFMS). We found that IO@MLGO4-8, the magnetic cluster with the greatest number of GO layers, had the best limit of detection (28.6 pmol/µL for glimepiride). The number of GO layers played a significant role in increasing the sensitivity of the SALDI-MS, indicating that the size of GO in the magnetic clusters contributed to the desorption/ionization efficiency. To the best of our knowledge, this is the first study to enrich glimepiride using magnetic clusters of different GO types and to show that the glimepiride in HLB purified urine adsorbed by magnetic clusters can be analyzed by SALDI-TOFMS.

Porous monolith-based magnetism-reinforced in-tube solid phase microextraction of sulfonylurea herbicides in water and soil samples.

In the present study, porous monolith-based magnetism-reinforced in-tube solid phase microextraction (MB-MR/IT-SPME) was first introduced to concentrate sulfonylurea herbicides (SUHs). To realize the effective capture of SUHs, a monolithic capillary microextraction column (MCMC) based on poly (vinylimidazole-co-ethylene dimethacrylate) polymer doped with Fe3O4 magnetic nanoparticles was in-situ synthesized in the first step. After that, the MCMC was twined with a magnetic coil which was employed to carry out variable magnetic field during adsorption and desorption procedure. Various important parameters that affecting the extraction performance were inspected in detailed. Results well indicated that exertion of magnetic field in the whole extraction procedure was in favor of the capture and release of the studied SUHs, with the extraction efficiencies increased from 36.8-58.1% to 82.6-94.5%. At the same time, the proposed MB-MR/IT-SPME was online combined to HPLC with diode array detection (HPLC/DAD) to quantify trace levels of SUHs in water and soil samples. The limits of detection (S/N = 3) for water and soil samples were in the ranges of 0.030-0.15 µg/L and 0.30-1.5 µg/kg, respectively. The relative standard deviations (RSDs) for intra- and inter-day variability were both less than 10%. Finally, the introduced approach was successfully applied to monitor the low contents of studied SUHs in environmental water and soil samples. Satisfying fortified recovery and precision were achieved.

Genome Mining and Enzymatic Total Biosynthesis of Purincyclamide.

A cyclodipeptide synthase-containing gene cluster (pcm) was identified in Streptomyces chrestomyceticus NA4264 through genome mining. Heterologous expression of the cryptic pcm gene cluster in Streptomyces albus led to the production of a new highly modified cyclodipeptide named purincyclamide (1). Bioinformatic analysis and gene knockout experiments revealed the biosynthetic pathway. The production of 1 was achieved through a one-pot enzymatic reaction.

Magnetic polydopamine modified with deep eutectic solvent for the magnetic solid-phase extraction of sulfonylurea herbicides in water samples.

A novel magnetic solid-phase extraction (MSPE) technique coupled with ultra performance liquid chromatography (UPLC) has been developed for the determination of four sulfonylurea herbicides (sulfosulfuron, bensulfuron-methyl, pyrazosulfuron-ethyl and halosulfuron-methyl) in aqueous samples. The key point of this method was the application of a novel magnetic nanomaterial (Fe3O4 @ PDA-DES). The functional groups, morphology, and magnetic properties of this magnetic nanomaterial were investigated through fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and X-ray diffraction (XRD) respectively. The main factors which could affect the experiment results were optimized. Under the optimum conditions, the linearity of this method ranged from 5.0-200 µg L-1 for all analytes, with correlation coefficients (r) ≥0.9901. The enrichment factors were between 495 and 630, and the relative standard deviations (RSDs) were less than 3.6%. The limits of detections (LODs) varied from 0.0098 to 0.0110 µg L-1. In the final experiment, the developed method has been successfully applied to the determination of sulfonylurea herbicides in environment and drinking water samples, and the obtained recoveries were between 61.3% and 108.6%.

Preparation of iron-based MIL-101 functionalized polydopamine@Fe3 O4 magnetic composites for extracting sulfonylurea herbicides from environmental water and vegetable samples.

Here, we describe a simple one-pot solvothermal method for synthesizing MIL-101(Fe)@polydopamine@Fe3 O4 composites from polydopamine-modified Fe3 O4 particles. The composite was used as a magnetic adsorbent to rapidly extract sulfonylurea herbicides. The herbicides were then analyzed by high-performance liquid chromatography. The best possible extraction efficiencies were achieved by optimizing the most important extraction parameters, including desorption conditions, extraction time, adsorbent dose, salt concentration, and the pH of the solution. Good linearity was found (correlation coefficients >0.9991) over the herbicide concentration range 1-150 µg/L using the optimal conditions. The limits of detection (the concentrations giving signal/noise ratios of 3) were low, at 0.12-0.34 µg/L, and repeatability was good (the relative standard deviations were <4.8%, n = 6). The method was used successfully to determine four sulfonylurea herbicides in environmental water and vegetable samples, giving satisfactory recoveries of 87.1-108.9%. The extraction efficiency achieved using MIL-101(Fe)@polydopamine@Fe3 O4 was compared with the extraction efficiencies achieved using other magnetic composites (polydopamine@Fe3 O4 , Hong Kong University of Science and Technology (HKUST)-1@polydopamine@Fe3 O4 , and MIL-100(Fe)@polydopamine@Fe3 O4 ). The results showed that the magnetic MIL-101(Fe)@polydopamine@Fe3 O4 composites have great potential for the extraction of trace sulfonylurea herbicides from various sample types.

Mixed functional monomers-based monolithic adsorbent for the effective extraction of sulfonylurea herbicides in water and soil samples.

Effective extraction is a key step in the determination of sulfonylurea herbicides (SUHs) in complicated samples. According to the chemical properties of SUHs, a new monolithic adsorbent utilizing acrylamidophenylboronic acid and vinylimidazole as mixed functional monomers was synthesized. The new adsorbent was employed as the extraction phase of multiple monolithic fiber solid-phase microextraction (MMF-SPME) of SUHs, and the extracted SUHs were determined by high-performance liquid chromatography with diode array detection (HPLC-DAD). Results well evidence that the prepared adsorbent could extract SUHs in environmental waters and soil effectively through multiply interactions such as boronate affinity, dipole-dipole and π-π interactions. Under the optimized extraction conditions, the limits of detection for target SUHs in environmental water and soil samples were 0.018-0.17µg/L and 0.14-1.23µg/kg, respectively. At the same time, the developed method also displayed some analytical merits including wide linear dynamic ranges, good method reproducibility, satisfactory sensitivity and low consume of organic solvent. Finally, the developed were successfully applied to monitor trace SUHs in environmental water and soil samples. The recoveries at three fortified concentrations were in the range of 70.6-119% with RSD below 11% in all cases. The obtained results well demonstrate the excellent practical applicability of the developed MMF-SPME-HPLC-DAD method for the monitoring of SUHs in water and soil samples.

Sorption potential of alkaline treated straw and a soil for sulfonylurea herbicide removal from aqueous solutions: An environmental management strategy.

The adsorption potential of alkaline treated straw (wheat and corn) in mixture with soil, has been investigated for the removal of sulfonylurea molecules from an aqueous solutions. The surface characteristics were investigated by scanning electron microscopy and Fourier Transform Infrared - FTIR, while the adsorbent capacity was evaluated using batch sorption tests and liquid chromatography coupled with mass spectrometry. Surface analysis of alkaline treated straw samples by scanning electron microscopy - SEM showed the increasing of the surface roughness improving their functional surface activity. An increase (337.22 mg g-1) of adsorption capacity of sulfonylurea molecules was obtained for all studied straw. The Langmuir isotherm model was the best model for the mathematical description of the adsorption process indicating the forming of a surface sorption monolayer with a finite number of identical sites. The kinetics of sulfonylurea herbicide followed the pseudo-second order mechanism corresponding to strong chemical interactions. The results sustained that the alkaline treated straw have biosorption characteristics, being suitable adsorbent materials.

Determination of six sulfonylurea herbicides in environmental water samples by magnetic solid-phase extraction using multi-walled carbon nanotubes as adsorbents coupled with high-performance liquid chromatography.

Magnetic solid-phase extraction (MSPE) using magnetic multi-walled carbon nanotubes (mag-MWCNTs) as adsorbents, coupled with high-performance liquid chromatography-diode-array detector (HPLC-DAD), was developed for the simultaneous separation and determination of six types of sulfonylurea herbicides (SUs) in environmental water samples. Several variables affecting MSPE efficiency were systematically investigated, including the type and volume of desorption solvent, sample solution pH, salt concentration, amount of mag-MWCNTs, and extraction and desorption time. Response surface was employed to assist in the MSPE optimization. Under optimized conditions, excellent linearity was achieved in the range of 0.05-5.0µg/L for all six SUs, with coefficients of correlation r>0.9994, and preconcentration factors ranging from 178 to 210. Limits of detection and quantification were 0.01-0.04µg/L and 0.03-0.13µg/L, respectively. The intra-day and inter-day precision (relative standard deviations, n=6, %) at three spiked levels were 2.0-11.0% and 2.1-12.9% in terms of peak area, respectively. The method recoveries at three fortified concentrations were obtained within 76.7-106.9% for reservoir water samples and 78.2-105.4% for tap water samples. The developed MSPE-HPLC method demonstrated high sensitivity, repeatability, simplicity, rapidity, and excellent practical applicability.

Core-shell magnetic molecularly imprinted polymers as sorbent for sulfonylurea herbicide residues.

Sulfonylurea herbicides are widely used at lower dosage for controlling broad-leaf weeds and some grasses in cereals and economic crops. It is important to develop a highly efficient and selective pretreatment method for analyzing sulfonylurea herbicide residues in environments and samples from agricultural products based on magnetic molecularly imprinted polymers (MIPs). The MIPs were prepared by a surface molecular imprinting technique especially using the vinyl-modified Fe3O4@SiO2 nanoparticle as the supporting matrix, bensulfuron-methyl (BSM) as the template molecule, methacrylic acid (MAA) as a functional monomer, trimethylolpropane trimethacrylate (TRIM) as a cross-linker, and azodiisobutyronitrile (AIBN) as an initiator. The MIPs show high affinity, recognition specificity, fast mass transfer rate, and efficient adsorption performance toward BSM with the adsorption capacity reaching up to 37.32 mg g(-1). Furthermore, the MIPs also showed cross-selectivity for herbicides triasulfuron (TS), prosulfuron (PS), and pyrazosulfuron-ethyl (PSE). The MIP solid phase extraction (SPE) column was easier to operate, regenerate, and retrieve compared to those of C18 SPE column. The developed method showed highly selective separation and enrichment of sulfonylurea herbicide residues, which enable its application in the pretreatment of multisulfonylurea herbicide residues.

Transformation of sulfonylurea herbicides in simulated drinking water treatment processes.

Sulfonylurea herbicides (SUs) were detected in natural waters and could be potentially exposed to human beings via portable use. Thus, the removal of five representative SUs in simulated water treatment processes including coagulation, activated carbon adsorption, and chlorination disinfection was systematically investigated. Results showed that coagulation had little effect on the removal of the herbicides with the average removal less than 10 %. Powder-activated carbon adsorption was apparently more effective with removal rates of 50 ~ 70 %. SUs were also partially removed in chlorination process. A complete removal was achieved when the three treatments were performed in series. However, it was found that parts of the SUs were transformed into certain stable products with triazine/pyrimidine structures which might be of potential health risks in chlorination process. Thus, current drinking water treatment processes are not likely to provide sufficient protection for human population from exposure to SUs.

Determination of four sulfonylurea herbicides in tea by matrix solid-phase dispersion cleanup followed by dispersive liquid-liquid microextraction.

Matrix solid-phase dispersion combined with dispersive liquid-liquid microextraction has been developed as a new sample pretreatment method for the determination of four sulfonylurea herbicides (chlorsulfuron, bensulfuron-methyl, chlorimuron-ethyl, and pyrazosulfuron) in tea by high-performance liquid chromatography with diode array detection. The extraction and cleanup by matrix solid-phase dispersion was carried out by using CN-silica as dispersant and carbon nanotubes as cleanup sorbent eluted with acidified dichloromethane. The eluent of matrix solid-phase dispersion was evaporated and redissolved in 0.5 mL methanol, and used as the dispersive solvent of the following dispersive liquid-liquid microextraction procedure for further purification and enrichment of the target analytes before high-performance liquid chromatography analysis. Under the optimum conditions, the method yielded a linear calibration curve in the concentration range from 5.0 to 10 000 ng/g for target analytes with a correlation coefficients (r(2)) ranging from 0.9959 to 0.9998. The limits of detection for the analytes were in the range of 1.31-2.81 ng/g. Recoveries of the four sulfonylurea herbicides at two fortification levels were between 72.8 and 110.6% with relative standard deviations lower than 6.95%. The method was successfully applied to the analysis of four sulfonylurea herbicides in several tea samples.

Preparation of molecularly imprinted polymer for use as SPE adsorbent for the simultaneous determination of five sulphonylurea herbicides by HPLC.

A high selective pre-treatment method for the analysis of sulphonylurea herbicides (SUHs) in rice grain samples based on molecularly imprinted solid-phase extraction (MISPE) was developed. The molecularly imprinted polymers (MIPs) were synthesised with high adsorption capacity and suitable particle size using pyrazosulphuron ethyl (PS) as the template and by screening three porogens and porogen volumes. The resulting MIPs showed high selectivity for PS. The MISPE procedure was developed for the purification and enrichment of PS, bensulphuron methyl (BSM), tribenuron methyl (TBM), metsulphuron methyl (MSM) and nicosulphuron (NS) from a rice grain sample prior to reversed-phase high-performance liquid chromatography (HPLC) analysis. Average recoveries of the PS, NS, MSM and BSM were 95.6%, 88.6%, 87.8% and 89.4%, respectively, but the recovery of TBM was lower (48.2%). This pre-treatment methodology for extracting SUHs was simple and cleaner extractions. The limits of detection ranged from 10.1 to 50.0ngL(-)(1). Five local rice grain samples were analysed by HPLC-MISPE, and PS was detected in all five samples, while BSM was detected in one sample.

[Degradation of nicosulfuron by combination effects of microorganisms and chemical hydrolysis].

A strain which was capable of degrading nicosulfuron in the presence of glucose was isolated from nicosulfuron contaminated wetland soil, and it was identified as Klebsiella sp. based on 16S rDNA gene sequencing analysis. The strain could grow using nicosulfuron as the sole nitrogen source. The optimal temperature was 35 degrees C and the initial pH was neutral to weak acid. Hydrolysis experiments indicated that nicosulfuron remained stably under neutral and alkaline conditions, while in acidic conditions, it hydrolyzed quickly. Based on biodegradation experiments, when the concentration of glucose in culture was 5 g x L(-1), the strain could degrade 99.4% of nicosulfuron after incubation for 10 days at 35 degrees C, initial pH = 7; pH of the solution decreased from initial 7.0 to 4.0 in the meantime. When the concentration of glucose in culture solution was decreased to 500 mg x L(-1) and 100 mg x L(-1), with other conditions unchanged, only 11.7% and 6.6% of nicosulfuron were degraded, respectively, and pH of the solution remained at around 7.0. It was proposed that the degradation of nicosulfuron was caused by hydrolysis under acidic conditions at low pH which was resulted from the biodegradation of glucose by the strain. Therefore, the removal of nicosulfuron was actually caused by combined effects of microorganisms and chemical hydrolysis.

Hollow-fiber liquid-phase microextraction combined with capillary HPLC for the selective determination of six sulfonylurea herbicides in environmental waters.

A three-phase hollow-fiber liquid-phase microextraction combined with a capillary LC method using diode array detection was proposed for the determination of six sulfonylurea herbicides, triasulfuron, metsulfuron-methyl, chlorsulfuron, flazasulfuron, chlorimuron-ethyl, and primisulfuron-methyl, in environmental water samples. Different factors that can affect the extraction process such as extraction solvent, acidity of the donor phase, composition and pH of the acceptor phase, salt addition, stirring speed, and extraction time were optimized. Under the optimum conditions, detection and quantitation limits between 0.1-1.7 and 0.3-5.7 µg/L, respectively, and enrichment factors ranging from 71 to 548 were obtained. The calibration curves were linear within the range of 0.3-40 µg/L. Intra- and interday RSDs were <6.3 and 8.4%, respectively. The relative recoveries of the spiked ground and river water samples were in the range of 69.4-119.2 and 77.4-111.7%, respectively. The results of the study revealed that the developed methodology involves an efficient sample pretreatment allowing the preconcentration of analytes, combined with the use of a miniaturized separation technique, suitable for the accurate determination of sulfonylurea herbicides in water.

Use of gold nanoparticle-coated sorbent materials for the selective preconcentration of sulfonylurea herbicides in water samples and determination by capillary liquid chromatography.

Two new gold nanoparticle (NP) coated materials (silica supported on gold NP with and without ionic liquid) were synthesized for solid phase extraction of sulfonylurea herbicides (SUHs), such as bensulfuron-methyl (BSM), metsulfuron-methyl (MSM), pyrazosulfuron-methyl (PSM), thifensulfuron-methyl (TFM) and triasulfuron (TS), from water samples, followed by capillary liquid chromatography coupled to diode array detection (CLC-DAD). Several factors influencing the preconcentration efficiency of SUHs and its subsequent determination, such as pH of the sample, eluent and reusability of sorbents, have been investigated. Under the optimum conditions, the developed method allowed the determination of BSM, MSM, PSM, TFM and TS in a linear range between 0.05 and 1.00 µg mL(-1), with relative standard deviation values lower than 4.5% (n=10), in all cases. Detection limits within 0.002-0.009 µg mL(-1) range were achieved. The usefulness of the proposed method was demonstrated by the analysis of river water samples, in which recoveries between 83.9 and 105.0% were obtained. The Au-NP-ionic liquid-functionalized silica sorbent showed higher recoveries (selectivity) for the SUHs than the commercially available C18 sorbents.

On-line preconcentration and determination of six sulfonylurea herbicides in cereals by MEKC with large-volume sample stacking and polarity switching.

A new MEKC method with large-volume sample stacking and polarity switching was developed for on-line preconcentration and detection of sulfonylurea herbicide (SUH) residues in cereals, including nicosulfuron (NS), thifensulfuon (methyl) (TFM), tribenuron-methly (TBM), sulfometuron-methyl (SMM), pyrazosulfuron-ethyl (PSE), and chlorimuron-ethyl (CME). In order to achieve a high resolution and enrichment factor, several parameters were optimized, such as the pH of the running buffer, the concentration of the BGE and the SDS, the separate voltage, the sample size, the pH, and the electrolyte concentration of the sample. The optimal running buffer was composed of 30 mM borate and 80 mM SDS at pH 7.0. The borate concentration in the sample was 30 mM and the pH value of the sample was the same as that of the running buffer. The concentrating voltage and the separating voltage were -15 kV and 15 kV, respectively. The sample size was 1.455 kPa × 780 s (33.11 cm). Under the optimum conditions, for NS, TFM, TBM, SMM, PSE, and CME, the enrichment factors were 613, 642, 835, 570, 709, and 599; the LODs were 0.29-0.50 ng/g, 0.22-0.36 ng/g, 0.60-0.89 ng/g, 0.39-0.72 ng/g, 0.28-0.56 ng/g, and 0.31-0.57 ng/g; the LOQs of six SUHs were all 5 ng/g; the average recoveries of the spiked sample were 86.68-92.99%, 80.73-93.65%, 81.49-94.40%, 82.97-95.1%, 82.96-98.84%, and 80.41-92.94%, respectively.

Ionic liquids supported on magnetic nanoparticles as a sorbent preconcentration material for sulfonylurea herbicides prior to their determination by capillary liquid chromatography.

A magnetic material based on N-methylimidazolium ionic liquid and Fe(3)O(4) magnetic nanoparticles incorporated in a silica matrix has been used to extract and preconcentrate sulfonylurea herbicides, such as thifensulfuron methyl (TSM), metsulfuron methyl (MSM), triasulfuron (TS), tribenuron methyl (TBM) and primisulfuron methyl (PSM) from polluted water samples, prior to their analysis by capillary liquid chromatography with a diode array detector (DAD). Under the optimum conditions, this method allows the determination of TSM, MSM, TS, TBM and PSM in a linear range between 5 and 100 ng mL(-1), with relative standard deviation values lower than 5.3% (n = 10), in all cases. Detection limits ranging between 1.13 and 2.95 ng mL(-1) were achieved. The usefulness of the proposed method was demonstrated by the analysis of river water samples, obtaining recoveries higher than 91%.