Zirconium(IV) functionalized magnetic nanocomposites for extraction of organophosphorus pesticides from environmental water samples

Design of reversibly charge-changeable rhodamine B modified magnetic nanoparticles to enrich phosphopeptides

In the present study, by employing ethylenediaminetetraacetic acid (EDTA), tetraethylene pentaamine (TEPA), and rhodamine B (Rb), we designed and synthesized a magnetic adsorbent (Fe₃O₄@EDTA@TEPA@Rb) on the basis of reversible charge change of Rb and applied to capture phosphopeptides. Rb existing in open planarized zwitterion form when stimulated by acidic loading buffer adsorbs negative phosphopeptides via electrostatic interaction. Under the stimulation of alkalic eluent, ring-closed structure of Rb is formed to elute the enriched phosphopeptides. TEPA containing rich amino groups is used as a crosslinking agent, which is also protonated in acidic loading buffer to bond phosphopeptides. Then phosphopeptides are eluted when TEPA deprotonates in alkalic eluent. Coupled with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) detection, phosphopeptide signals originated from 0.4 fmol/μL β-casein digests were successfully detected. In addition, Fe₃O₄@EDTA@TEPA@Rb can also efficiently enrich phosphopeptides from skimmed milk, human serum and saliva samples (26, 4, 39 phosphopeptides, respectively), opening a new gallery for phosphopeptides-related analysis. In general, the developed adsorbent has the great potential for further application in the near future.

Ag-EDTA-Zr and Au-EDTA-Zr Nanocomposites for the Quantitative Determination of Some Organophosphate Pesticides in Water and Tomatoes

Background

Organophosphate pesticides (OP) pose risks to health and the environment, and monitoring them is an urgent task.

Objective

Development of a method for their determination in water and food.

Method

A simple photometric method for the determination of some OPs was demonstrated. Ag-EDTA-Zr and Au-EDTA-Zr nanoparticles were synthesized and were applied for the determination of some OPs (dimethoate, chlorpyrifos, and diazinon).

Results

It was demonstrated that silver nanoparticles provide more sensitivity in comparison to gold nanoparticles. As a result, Ag-EDTA-Zr nanoparticles were further applied for the determination of these pesticides in tomatoes.

Conclusions

The lowest detectable concentrations for dimethoate, diazinon, and chlorpyrifos in water reached 0.1 (SD 0.082), 0.4 (SD 0.075), and 0.4 mg/L (SD 0.088), respectively, whereas in tomato the lowest detectable concentrations for these pesticides were 0.5 (SD 0.789), 2 (SD 0.085), and 0.5 mg/L (SD 0.088). The sensitivity of detection in tomatoes is lower than in water; however, these concentrations are comparable with allowable concentrations of OP pesticides.

Highlights

A novel approach for quantitative detection of OPs was developed. Ag-EDTA-Zr and Au-EDTA-Zr nanocomposites interact with these pesticides, and, as a result, optical changes of these nanoparticles take place. These changes correlate with the concentration of pesticides.

Preparation of magnetic molecularly imprinted polymer based on multiwalled carbon nanotubes for selective dispersive micro-solid phase extraction of fenitrothion followed by ion mobility spectrometry analysis

A novel molecularly imprinted polymer based on magnetic multi-walled carbon nanotubes was fabricated and applied for selective dispersive micro-solid phase extraction of fenitrothion prior its determination by ion mobility spectrometry. The composite was synthesized using magnetic multi-walled carbon nanotubes as the support. Methacrylic acid was used as the functional monomer, fenitrothion as the template, ethylene glycol dimethacrylate as the cross-linker and 2,2-azoisobutyronitrile as the initiator. The resultant polymer was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmet-Teller analysis, thermogravimetric analysis and vibrating sample magnetometer techniques. Experimental factors affecting the extraction efficiency such as pH and amount of sorbent were evaluated. Under optimum experimental conditions, the developed method displayed the linear range of 5-220 μg L^-1 with a detection limit (LOD) of 1.3 μg L^-1 . The intra and inter-day relative standard deviations (RSD%) for determination of fenitrothion were 3.6 and 4.7% (n = 6), respectively. Ultimately, the proposed method was used to monitoring of trace amounts of fenitrothion in fruit,vegetable and water samples. This article is protected by copyright. All rights reserved.

Chromatographic techniques for the analysis of organophosphate pesticides with their extraction approach: a review (2015-2020)

In agriculture, a wide range of OPPs has been employed to boost crop yield, quality, and storage life. However, due to the ever-increasing population and rapid urbanization, pesticide use has surged in recent years. These compounds are exceedingly poisonous to humans, and despite the fact that specific legislation prohibits their use, the frequency of toxic and/or fatal incidents, as well as current statistics, suggest that they are currently accessible. As a result, determining the exposure to these substances as well as their detection (and that of their metabolites) in different types of exposed samples has become a hot issue in terms of quality and safety concerns. However, developing tools for the evaluation of these substances is a critical challenge for laboratories. Various chromatographic-based methods reported in the period of 2015-2020 have been developed, which are summarized and critically reviewed in this article, including the extraction of the target OPPs from different kinds of matrices. A comparison among the extraction and analysis techniques has been made in the current review article.

Novel Fe3O4@metal-organic framework@polymer core-shell-shell nanospheres for fast extraction and specific preconcentration of nine organophosphorus pesticides from complex matrices

Herein, a novel core-shell-shell magnetic nanosphere denoted as Fe₃O₄@ZIF-8@polymer was fabricated by sequential in situ self-assembly and precipitation polymerization for effective magnetic solid-phase extraction of nine organophosphorus pesticides (OPPs) from river water, pear, and cabbage samples. The integrated Fe₃O₄@ZIF-8@polymer featured convenient magnetic separation property and excellent multi-target binding ability. More importantly, the functional polymer coating greatly improved the extraction performance of Fe₃O₄@ZIF-8 for OPPs, thus facilitating the simultaneous determination of trace OPP residues in real samples. The developed MPSE-LC-MS/MS method exhibited good linearity (R² ≥ 0.9991) over the concentration range of 0.2-200 µg L^-1, low limits of detection of 0.0002-0.005 μg L^-1 for river water and 0.006-0.185 μg kg^-1 for pear and cabbage, satisfactory precision with relative standard deviations ≤ 9.7% and accuracy with recoveries of 69.5-94.3%. These results highlight that the combination of polymers with MOFs has great potential to fabricate excellent adsorbents for high-throughput analysis of various contaminants in complex matrices.

A facile "one-material" strategy for tandem enrichment of small extracellular vesicles phosphoproteome

Small extracellular vesicles (SEVs), are cell-derived, membrane-enclosed nanometer-sized vesicles that play vital roles in many biological processes. Recent years, more and more evidences proved that small EVs have close relationship with many diseases such as cancers and Alzheimer's disease. The use of phosphoproteins in SEVs as potential biomarkers is a promising new choice for early diagnosis and prognosis of cancer. However, current techniques for SEVs isolation still facing many challenges, such as highly instrument dependent, time consuming and insufficient purity. Furthermore, complex enrichment procedures and low microgram amounts of proteins available from clinical sources largely limit the throughput and the coveage depth of SEVs phosphoproteome mapping. Here, we synthesized Ti⁴⁺-modified magnetic graphene-oxide composites (GFST) and developed a "one-material" strategy for facile and efficient phosphoproteome enrichment and identification in SEVs from human serum. By taking advantage of chelation and electrostatic interactions between metal ions and phosphate groups, GFST shows excellent performance in both SEVs isolation and phosphopeptide enrichment. Close to 85% recovery is achieved within a few minutes by simple incubation with GFST and magnetic separation. Proteome profiling of the isolated serum SEVs without phosphopeptide enrichment results in 515 proteins, which is approximately one-fold more than those otained by ultracentrifugation or coprecipitation kits. Further application of GFST in one-material-based enrichment led to identification of 859 phosphosites in 530 phosphoproteins. Kinase-substrate correlation analysis reveals enriched substrates of CAMK in serum SEVs phosphoproteome. Therefore, we expect that the low instrument dependency and the limited sample requirement of this new strategy may facilitate clinical investigations in SEV-based transportation of abnormal kinases and substrates for drug target discovery and cancer monitoring.

Mesoporous MIP-capped luminescent MOF as specific and sensitive analytical probe: application for chlorpyrifos

Specific recognition of organophosphate pesticides (OPs) is a significant challenge for analytical researchers. Herein, surface imprinted terbium-based luminescent metal-organic framework (MOF-76) are presented as a highly specific probe for the measurement of chlorpyrifos (CP). A mesoporous molecular imprinted polymer (mMIP) layer was generated on the surface of nano-sized MOF-76 using CP, as template. The resulting mMIP-capped MOF-76 (mMIP@MOF-76) contained specific sites for adsorption of CP molecules, guaranteeing the selectivity of the designed probe. The high porosity of rod-shape MOF-76, as well as the mesoporous structure of the MIP layer improved the diffusion process and caused the high sensitivity of the probe. The detection process is based on the remarkable quenching effect of CP on the fluorescence emission of mMIP@MOF-76. Plotting the CP concentration against the fluorescence intensity (λ_ex = 285 nm and λ_em = 544 nm) gave a linear curve in the concentration range 10-1000 ng mL^-1 CP, with 3.41 ng mL^-1 limit of detection. The designed probe was utilized for CP determination in fruit juice and environmental samples. The combination of the stable MOF-based support, as well as its remarkable fluorescence features and specific MIP sites, led to a highly selective and ultrasensitive detection system.Graphical abstract.

Polydimethylsiloxane/ionic liquid sponge used in headspace solid-phase extraction coupled with GC-MS for rapid analysis of essential oil in lavender

A headspace (HS) solid-phase extraction (SPE) based on polydimethylsiloxane (PDMS)/ionic liquid (IL) sponge was developed for the extraction of lavender essential oil. The PDMS after loading of 1-butyl-3-methylimidazolium tetrachloroferrate ([BMIM]FeCl₄ ) with a high surface area and excellent adsorption capacity was successfully applied in the SPE process. Microwave distillation (MD) coupled with HS-PDMS/[BMIM]FeCl₄ extraction after GC-MS was proposed. Various experimental parameters were studied. The optimal conditions were as follows: optimal IL, [BMIM]FeCl₄ ; volume ratio of IL to ethanol, 1:5; extraction solvent, n-hexane; microwave power, 600 W; and irradiation time, 12 min. The limits of detection and quantification of the analytic compounds were in the ranges 4.00-16.32 and 10.00-40.00 ng, respectively. The intra-day and inter-day precisions were in the ranges 0.37-1.94% and 1.20-2.45%, respectively. Under the optimized conditions, 13 samples of 3 lavender varieties were analyzed, and 40 compounds were identified. Lavender varieties were distinguished using principal component analysis. The results showed that MD-HS-PDMS/IL-GC-MS is a novel, simple, and sensitive method for the determination of essential oil in complex plant samples.

Fabrication of zirconium (IV)-loaded chitosan/Fe3O4/graphene oxide for efficient removal of alizarin red from aqueous solution

Zirconium(IV)-loaded chitosan/Fe₃O₄/graphene oxide (Zr-CMGO) was fabricated and applied to remove alizarin red (AR) from aqueous solution. Characterizations of Zr-CMGO were performed using several techniques. The effects of initial AR pH, coexisted NaCl, contact time and AR concentration were systematically investigated in batch mode. The increased pH had a negative effect on AR adsorption while there was little impact with salinity. Adsorption capacity toward AR reached up to 231 mg/g at 313 K. The kinetic and isotherm analyses indicated that pseudo-second-order kinetic model and Freundlich model could predicted the uptake of AR. In addition, the mechanism of AR adsorption could be mainly complexation, electrostatic force, etc. There is antibacterial activity from test about Zr-CMGO. Furthermore, the two-stage design could be applied for the theoretical support. Based on all results, Zr-CMGO is a novel and selective adsorbent for practical applications.

Development, validation, comparison, and implementation of a highly efficient and effective method using magnetic solid-phase extraction with hydrophilic-lipophilic-balanced materials for LC-MS/MS analysis of pesticides in seawater

To achieve multi-pesticides residue analysis in seawater, hydrophilic-lipophilic-balanced magnetic particles were designed and fabricated by swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe₃O₄@SiO₂ magnetic particles. The ratio of DVB to NVP was adjusted to achieve a proper balance in hydrophilicity and lipophilicity. The obtained magnetic particles were systematically characterized by TEM, SEM, FT-IR and vibrating sample magnetization. Based on the optimized magnetic nanoparticles, a sensitive magnetic solid-phase extraction method was developed for the simultaneous pre-concentration and determination of 96-pesticide residues from large-volume seawater samples prior to being detected by liquid chromatography-tandem mass spectrometry. Recoveries of pesticides in spiked seawater samples (0.001, 0.01, 0.1, 1.0 μg L^-1) ranged from 62% to 112% with RSDs less than 21%. The method limits of detection of 96 pesticides ranged from 0.13 to 0.42 ng L^-1, the method limits of quantification of 96 pesticides ranged from 1.0 to 10 ng L^-1. The method was successfully applied to pesticide residue analysis in water samples from Jiulong River Estuary of China, demonstrating the prospects of this technique as a potential method for the rapid determination of trace levels of multi-pesticide residues in seawater.

A glassy carbon electrode modified with a monolayer of zirconium(IV) phosphonate for sensing of methyl-parathion by square wave voltammetry

A glassy carbon electrode (GCE) was consecutively modified with amino groups and phosphate groups, and then loaded with Zr(IV) ions. Fourier transform infrared spectrophotometry, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy and cyclic voltammetry were used to characterize the morphologies and electrochemical properties. The sensor was used to detect p-nitrophenyl-substituted organophosphorus pesticides, with methyl-parathion (MP) as the model analyte. Under optimized conditions, the oxidation current of square wave voltammetry (typically measured at around -0.28 V vs. saturated calomel electrode) increases linearly in the 1.0 to 100 ng mL^-1 MP concentration range, and the detection limit is 0.25 ng mL^-1 (at a signal to noise ratio of 3). Average recoveries from (spiked) real water samples are 99.9-102.2%, with relative standard deviations of 0.3-2.6% (n = 3) at three levels. The reliability and accuracy of the method was validated by HPLC. Graphical abstract Zr(IV) modified GCE is prepared via three steps. The electrode shows high specificity and selectivity towards methyl-parathion. And the linear range is 1.0 - 100.0 ng mL-¹ with the detection limit as low as 0.25 ng mL-¹ with SWV.

Application of fabric phase sorptive extraction with gas chromatography and mass spectrometry for the determination of organophosphorus pesticides in selected vegetable samples

In the present work, a high-efficiency and solvent minimized microextraction technique, fabric phase sorptive extraction followed by gas chromatography and mass spectrometry analysis is proposed for the rapid determination of four organophosphorus pesticides (terbufos, malathion, chlorpyrifos, and triazofos) in vegetable samples including beans, tomato, brinjal, and cabbage. Fabric phase sorptive extraction combines the beneficial features of sol-gel derived microextraction sorbents with the rich surface chemistry of cellulose fabric substrate, which collectively form a highly efficient microextraction system. Fabric phase sorptive extraction membrane, when immersed directly into the sample matrix, may extract target analytes even when high percentage of matrix interferents are present. The technique also greatly simplifies sample preparation workflow. Most important fabric phase sorptive extraction parameters were investigated and optimized. The developed method displayed good linearity over the concentration range 0.5-500 ng/g. Under optimum experimental conditions, the limits of detection were found in the range of 0.033 to 0.136 ng/g. The relative standard deviations for the extraction of organophosphorus pesticides were < 5%. Subsequently, the new method was applied to beans, tomato, brinjal, and cabbage samples. The results from the real sample analysis indicate that the method is green, rapid, and economically feasible for the determination of organophosphorus pesticides in vegetable samples.

Magnetite-sporopollenin/graphene oxide as new preconcentration adsorbent for removal of polar organophosphorus pesticides in vegetables

In this study, a new magnetic adsorbent based on magnetite-sporopollenin/graphene oxide (Fe₃O₄-SP/GO) was successfully developed. The adsorbent was applied for magnetic solid phase extraction (MSPE) of three selected polar organophosphorus pesticides (OPPs), namely, dimethoate, phenthoate, and phosphamidon, prior to gas chromatography analysis with electron capture detection (GC-μECD). The Fe₃O₄-SP/GO adsorbent combines the advantages of superior adsorption capability of the modified sporopollenin (SP) with graphene oxide (GO) and magnetite (Fe₃O₄) for easy isolation from sample solution. Several MSPE parameters were optimized. Under optimized conditions, excellent linearity (R² ≥ 0.9994) was achieved using matrix match calibration in the range of 0.1 to 500 ng mL^-1. The limit of detection (LOD) method (S/N = 3) was from 0.02 to 0.05 ng mL^-1. The developed Fe₃O₄-SP/GO MSPE method was successfully applied for the determination of these three polar OPPs in cucumber, long beans, bell pepper, and tomato samples. Good recoveries (81.0-120.0%) and good relative standard deviation (RSD) (1.4-7.8%, n = 3) were obtained for the spiked OPPs (1 ng mL^-1) from real samples. This study is beneficial for adsorptive removal of toxic pesticide compounds from vegetable samples.

Dual-Readout Immunochromatographic Assay by Utilizing MnO2 Nanoflowers as the Unique Colorimetric/Chemiluminescent Probe

Manganese dioxide nanoflowers (MnO₂ NFs) were synthesized and used as a dual readout probe to develop a novel immunochromatographic test strip (ITS) for detecting pesticide residues using chlorpyrifos as the model analyte. MnO₂ NFs-labeled antibody for chlorpyrifos was employed as the signal tracer for conducting the ITS. After 10 min competitive immunoreaction, the tracer antibody was captured by the immobilized immunogen in the test strip, resulting in the captured MnO₂ NFs on test line. The captured MnO₂ NFs led to the appearance of brown color on the test line, which could be easily observed by the naked eye as a qualitative readout. Due to the very slight colorimetric difference of chlorpyrifos at trace concentrations, the semiquantitative readout by naked eyes could not meet the demand of quantitative analysis. MnO₂ NFs showed a significant effect on the luminol-H₂O₂ chemiluminescent (CL) system, and the CL signal driven by MnO₂ NFs were used to detect the trace concentration of chlorpyrifos quantitatively. 1,3-Diphenylisobenzofuran quenching studies and TMB-H₂O₂ coloration assays were conducted for studying the enhancing mechanism of MnO₂ NFs, which was based on the oxidant activity to decompose H₂O₂ for forming reactive oxygen species. Under optimal conditions, the linear range of chlorpyrifos was 0.1-50 ng/mL with a low detection limit of 0.033 ng/mL (S/N = 3). The reliability of the dual-readout ITS was successfully demonstrated by the application on traditional Chinese medicine and environmental water samples. Due to the simultaneous rapid-qualitative and sensitive-quantitative detection, the dual-readout protocol provides a promising strategy for rapid screening and field assay on various areas such as environmental monitoring and food safety.

Determination of six organophosphorus pesticides in water samples by three-dimensional graphene aerogel-based solid-phase extraction combined with gas chromatography/mass spectrometry

In the present study, a three-dimensional graphene aerogel (3D-GA), synthesised by chemical reduction of an aqueous solution of graphene oxides (GOs) with ethylenediaminethermal by a simple water bath method followed by freeze-drying treatment, was used for the solid-phase extraction (SPE) of six organophosphorus pesticides (OPPs) (i.e. trichlorfon, dimethoate, ethoprophos, parathion, fenitrothion and fenthion) from water samples. The target analytes were extracted using packed SPE cartridges and then eluted with tetrahydrofuran. The eluate was collected and dried with high-purity nitrogen gas at room temperature. After redissolving in acetone, the residue was analysed using gas chromatography/mass spectrometry (GC/MS). The proposed method demonstrated a good linearity between 0.5 and 500 μg L-1 with the correlation coefficient of 0.9990-0.9998. The limits of detection (LODs) (S/N = 3) and the limits of quantification (LOQs) (S/N = 10) for the six OPPs pesticides were in the range of 0.12-0.58 μg L-1 and 0.41-1.96 μg L-1, respectively. The accuracy of the present method was evaluated by measuring the recovery of the spiked samples, which ranged from 93.8% to 104.2% with relative standard deviations (RSDs) of 1.1-5.6%. The established method was successfully applied to the determination of the target analytes in environmental water samples including tap water, river water, drinking water and lake water, demonstrating its great potential for the determination of OPPs in water.