Anticancer Drug Extraction from Plasma Samples Using Three-Dimensional Polyoxometalate-Based Supramolecular Frameworks as Sorbents.

Four self-assembled inorganic-organic hybrid materials, namely, H{Na(H2O)3[Gd(PDA)(H2O)2]3[BW12O40]}·4H2O (1), H{Na(H2O)3[Tb(PDA)(H2O)2]3[BW12O40]}·3H2O (2), H{Na(H2O)3[Er(PDA)(H2O)3]3[BW12O40]}·H2O (3) (PDA = 1,10-phenanthroline-2,9-dicarboxylate), and [Pr3(H2O)13(pydc-OH)2][BW12O40]·12H2O (4) (pydc-OH = 4-hydroxy-2,6-pyridinedicarboxylate), were hydrothermally synthesized and structurally characterized. Hybrids 1-3 are isostructural and contain a Keggin unit, which is linked to lanthanoids to produce distinct trinuclear lanthanoid building blocks. The fragments are connected by anion-π and hydrogen bonding interactions to create 3D networks. In hybrid 4, a trimeric Pr-organic species bearing a Keggin unit forms a 2D coordination polymer, and then hydrogen bonding interactions between 2D layers lead to the formation of a 3D structure. These polyoxometalate-based frameworks were used as sorbents for the dispersive microsolid-phase extraction (D-µSPE) of two anticancer drugs (doxorubicin and epirubicin) in human plasma samples. Analytes were quantified and separated using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The method's linearity was between 0.8-500 ng mL-1 and 1.0-500 ng mL-1 for the antineoplastic drugs doxorubicin and epirubicin, respectively. The limits of detection (S/N = 3) were in the range of 0.2-0.3 ng mL-1, while the precision was in the range of 3.5-4.3%. Finally, human plasma samples from patients treated with doxorubicin or epirubicin were analyzed by using the D-µSPE-HPLC-FLD method.

Magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from water samples using magnetic carbon nanofiber/MIL-101(Cr) nanocomposites.

In this study, magnetic carbon nanofibers (Fe3O4@CNF) were modified with MIL-101(Cr) (Fe3O4@CNF@MIL-101) and used as sorbents for magnetic solid-phase extraction (MSPE) to extract polycyclic aromatic hydrocarbons (PAHs) from real water samples. Gas chromatography coupled with a flame ionization detector (GC-FID) was used for the determination of the PAHs. The effect of experimental variables on the extraction efficiency of PAHs was investigated and optimized. These variables include the quantity of sorbent, the kind and volume of the elution solvent, the duration of extraction and desorption, and the salt concentration. The linear range was found to be 0.01 to 200 ng mL-1 with correlation coefficients ranging from 0.9906 to 0.9931 after the effective extraction parameters were optimized. Its detection limits (LOD) were also calculated to be between 0.003 and 0.005 ng mL-1 (S/N = 3). The method's repeatability was tested at three different concentration levels (0.1, 1, and 10 ng mL-1), and relative standard deviations (RSDs%) were obtained in the range of 2.3 to 5.0%. Finally, using the MSPE-GC-FID method, PAHs were extracted from tap water, wastewater, seawater, and spring water samples. The relative recoveries were in the range of 95.7 to 99.8%.

Water desalination using stainless steel meshes coated with layered double hydroxide/graphene oxide nanocomposite.

Coated stainless steel meshes with layered double hydroxides and graphene oxide nanocomposites (LDH/GO) were used as desalination membranes. The nature of stainless steel mesh allows a greater amount of sorbent to be coated on the surface using sol-gel technique and increases the adsorption capacity of ions and the efficiency of desalination. These substrates improve the contact surface area so that approximately 5 min is required for the desalination process. The LDH/GO stainless steel mesh exhibited excellent corrosion resistance and tensile strength of 99.9% and 112 MPa, respectively. To achieve the best desalination efficiency, different parameters were optimized, including the ratio of GO to LDH in the nanocomposites, the number of mesh layers, NaCl concentrations, and process cycles. The maximum adsorption capacity for the NaCl was 555.5 mg g-1 . The results revealed that LDH/GO nanocomposite was able to remove (94.3 ± 0.5) % of the NaCl under the optimum conditions. The proposed method was used to successfully remove Na+ , Mg+2 , Ca+2 , and K+ cations from seawater, with the yields of 92.3%, 92.5%, 91.2%, and 90.2%, respectively. PRACTITIONER POINTS: The salts are removed via interaction between salt ions and functional groups on the LDH/GO nanocomposite surface. A high amount of adsorbent loaded on the surface of steel mesh leads to an improvement in the adsorption capacity. The sol-gel technique strengthens the LDH/GO nanocomposites on the surface of steel mesh.

Electrospun mesh pattern of polyvinyl alcohol/zirconium-based metal-organic framework nanocomposite as a sorbent for extraction of phthalate esters.

Herein, an electrospun composite polyvinyl alcohol/zirconium-based metal-organic frameworks (PVA@UiO-66) nanofiber coating was prepared on the surface of stainless steel mesh (SSM) and then utilized as novel sorbent for the extraction of phthalate esters (PEs) in milk and water samples. Gas chromatography equipped with a flame ionization detector (GC-FID) was used for the quantitative determination of extracted analytes. The SSM coated with PVA@UiO-66 was used in a polypropylene syringe to fabricate the solid-phase extraction (SPE) device. The PVA@UiO-66 nanofiber coating was confirmed using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy analysis (FT-IR), and field emission scanning electron microscopy (FESEM). The effective parameters of the extraction efficiency including volume and type of desorption solvent, sample volume, ionic strength, pH, extraction flow rate, and desorption flow rate were optimized. At the optimal extraction conditions, the calibration plots for phthalate esters were linear within the range of 0.05-100 ng mL-1 and, low detection limits (0.015-0.06 ng mL-1). Finally, this semi-automated SPE was used for the extraction and detection of phthalate esters (PEs) in milk and various environmental real water samples. The results showed good precision with acceptable and satisfactory extraction recovery values ranging from 89.5 to 99.2% and relative standard deviations (RSDs%) ranging from 4.5 to 6.9%.

Conductive Polymer-Based Nanocomposites as Powerful Sorbents: Design, Preparation and Extraction Applications.

Conductive polymers as composite materials have been attracted tremendous attention due to their versatile and excellent features such as tunable conductivity, facile synthesis and fabrication, high chemical and thermal stability etc. These characteristics make them versatile and let them being used in numerous fields including microelectronics, optics and biosensors. Throughout the mentioned fields, conductive polymers particularly perform as effective sorbents. Although tremendous efforts have been put into this topic, to the best of our knowledge, a comprehensive up-to-date review on the applications of conductive polymers as efficient sorbents has not been reported. The main objective of this paper is to make a significant contribution to the recent literature toward the synthesis and extraction applications of conductive polymers as efficient sorbents.

Opioid Drug Detection in Hair Samples Using Polyoxometalate-Based Frameworks.

A series of two-dimensional (2D) polyoxometalate-based frameworks, [Ln3(PDA)3(H2O)6(PMo12O40)]·xH2O (Ln = La (1); Ce (2); Pr (3); Nd (4); PDA = 1,10-phenanthroline-2,9-dicarboxylate), have been synthesized and structurally characterized by various analytical techniques. Single-crystal X-ray diffraction reveals that 1-4 have a unique 2D layer structure in which Keggin anions have coordinated upward and downward the plane, and this feature makes them suitable candidates for surface binding of common drugs via supramolecular and electrostatic interactions. Also, the ability of 1-4 (as the first polyoxomolybdate-containing frameworks) as sorbents for the extraction and quantitative determination of opioid drugs (morphine, methadone, and pethidine) was investigated by using dispersive micro-solid-phase extraction (D-µSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges in the range of 0.3 to 300 ng mg-1 and low limits of detection (LODs) ranged from 0.1 to 0.2 ng mg-1 of hair.

Nanofiber-based sorbents: Current status and applications in extraction methods.

Advanced sorbents gradually become a research hotspot on account of the increasing attention paid to environmental problems. Due to the prominent physicochemical features of nanofibers (NFs), such as high porosity, large surface area, favorable interconnectivity, high adsorption capacity, wettability, and the possibility of surface modification using functional groups, these nanostructures are regarded as excellent candidates for extraction applications. Therefore, the research in the field of NFs and their nanocomposites has been increasing in recent years. In the present review, we summarize the most recent studies on NFs-based sorbents focusing on strategies for preparation, characterization, and their unique capabilities as porous sorbents in various sorbent-based extraction methods. Moreover, we further described the performance and selectivity of sorbents to achieve improved extraction efficiency. Finally, some perspectives on the challenges and outlook are provided to aid future investigations related to this topic.

A critical review of covalent organic frameworks-based sorbents in extraction methods.

Recently, covalent organic frameworks (COFs) as an important class of porous frameworks have been employed in analytical applications owing to their significant inherent properties such as a high specific surface area with modifiable pore size and a robust nature that leads to great stabilities. Also, COFs are flexible in design to deliberate changes in their physical or chemical properties by generating functionalized COFs or COF-based composites. Here, we summarize some important categories of COFs from the point of view of their design and synthetic strategies. Subsequently, the synergistic combination aspects of COFs with other materials such as different types of magnetic, metal/metal oxide nanoparticles, silica, carbon nanomaterials, polymers, polyoxometalates (POMs), metal-organic frameworks (MOFs), and COFs are reviewed. Finally, the recent applications of COFs as efficient sorbents in analytical sample preparation methods including solid-phase extraction (SPE), dispersive solid-phase extraction (dSPE), magnetic solid-phase extraction (MSPE), and solid-phase microextraction (SPME) will be surveyed with emphasis on important factors that lead to increase extraction efficiency. In addition, challenges and obstacles in these approaches are discussed with perspective highlights.

Magnetic solid-phase extraction of organophosphorus pesticides from apple juice and environmental water samples using magnetic graphene oxide coated with poly(2-aminoterephthalic acid-co-aniline) nanocomposite as a sorbent.

An effective magnetic solid-phase extraction method was proposed using magnetic graphene oxide coated with poly(2-aminoterephthalic acid-co-aniline) as a sorbent for preconcentration and extraction of organophosphorus pesticides from environmental water and apple juice samples, and determined using the gas chromatography-mass spectrometry analysis. To approve the successful synthesis of the magnetic nanocomposite, the prepared sorbent was characterized by field emission scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Fourier transforms infrared techniques. The main parameters affecting the extraction efficiency were considered and studied to afford an optimized procedure. Systematic method validation verified its suitable recoveries (89.4-107.3%), and precision (relative standard deviations < 6.8%). The method showed a wide linear dynamic range (0.04-700 ng/mL) with low limits of detection (0.01-0.06 ng/mL) and quantification (0.04-0.21 ng/mL). This method presented good potential and great sensitivity for the pesticides determination.

Role of different types of nanomaterials against diagnosis, prevention and therapy of COVID-19.

In 2019, a novel type of coronavirus emerged in China called SARS-COV-2, known COVID-19, threatens global health and possesses negative impact on people's quality of life, leading to an urgent need for its diagnosis and remedy. On the other hand, the presence of hazardous infectious waste led to the increase of the risk of transmitting the virus by individuals and by hospitals during the COVID-19 pandemic. Hence, in this review, we survey previous researches on nanomaterials that can be effective for guiding strategies to deal with the current COVID-19 pandemic and also decrease the hazardous infectious waste in the environment. We highlight the contribution of nanomaterials that possess potential to therapy, prevention, detect targeted virus proteins and also can be useful for large population screening, for the development of environmental sensors and filters. Besides, we investigate the possibilities of employing the nanomaterials in antiviral research and treatment development, examining the role of nanomaterials in antiviral- drug design, including the importance of nanomaterials in drug delivery and vaccination, and for the production of medical equipment. Nanomaterials-based technologies not only contribute to the ongoing SARS- CoV-2 research efforts but can also provide platforms and tools for the understanding, protection, detection and treatment of future viral diseases.

Solid-phase extraction of non-steroidal anti-inflammatory drugs in human plasma and water samples using sol-gel-based metal-organic framework coating.

In this research, the Cu-based metal-organic framework (MOF-199) was fabricated and coated on the stainless steel mesh as substrates through sol-gel procedure. Then the coated substrates were placed in a small column known as solid-phase extraction cartridge. The SPE based coated stainless steel mesh coupled with high-performance liquid chromatography-UV detector (HPLC-UV) was used for the fast extraction, and quantification of non-steroidal anti-inflammatory drugs (NSAIDs) from human plasma and water samples. To find optimum extraction conditions, the impacts of effective parameters on analytical performance like sample pH, sample volume, type, and volume of desorption solvent were optimized. At the optimized conditions, calibration graphs of analytes were linear in the concentration range of 0.03-300 ng mL-1 for water samples, and 0.1-200 ng mL-1 for plasma samples. The correlation coefficients were in the range of 0.9938 to 0.9989. Also, the limits of detection (LODs) were from 0.01 to 0.02 ng mL-1 for water samples and 0.03 to 0.1 ng mL-1 for plasma samples. The cartridge repeatability was studied at different values, and the relative standard deviations (RSDs%) were achieved between 3.5 and 5.1%. Consequently, this procedure was successfully used in the extraction and detection of NSAIDs in real water and plasma samples with relative recoveries ranged from 93.6 to 99.6%.

Organophosphorus pesticides extraction with polyvinyl alcohol coated magnetic graphene oxide particles and analysis by gas chromatography-mass spectrometry: Application to apple juice and environmental water.

In this study, we synthesized, characterized the magnetic graphene oxide coated with polyvinyl alcohol (PVA@MGO), and used it as an adsorbent for the magnetic solid-phase extraction (MSPE) of organophosphorus pesticides (OPPs) residue in the apple juice and environmental water samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. Effective factors on the extraction efficiency, including the adsorbent dosage, desorption conditions, sample pH, extraction and desorption time, and ionic strength were optimized. The dynamic range of the MSPE-GC-MS method was obtained in the concentration range of 0.07-500 ng mL-1 OPPs with the limits of detection (LODs) in the range of 20-80 pg mL-1. Also, the intra- and inter-day precisions were determined to be in the range of 3.3-5.7% and 5.9-8.2%. The relative recoveries of pesticides for spiked real water samples and apple juice were in the range of 94.5 and 107.1%, with relative standard deviations between 2.6 and 6.5%. These results propose that the PVA@MGO is appropriate for simultaneous determination and high throughput analysis of OPPs residues.

Efficient dispersive micro solid-phase extraction of antidepressant drugs by a robust molybdenum-based coordination polymer.

A molybdenum-based coordination polymer {[Mo(PDA)(NO)(µ-O)MoO3]·1.42H2O·0.58C2H5OH}n (1) (PDA is 1,10-phenanthroline-2,9-dicarboxylate) was synthesized using solvothermal reaction conditions and characterized using a suite of analytical techniques. Single-crystal X-ray diffraction studies reveal a 1D chain structure, with close contacts expanding the structure into 3D including π-interactions and hydrogen bonding. The utility of 1 as a sorbent for dispersive micro solid-phase extraction (D-µSPE) of basic organic compounds such as antidepressants is supported by the presence of many functional groups on the surface of 1 (such as pendant carboxylates, Mo=O, Mo-NO, and CH groups) as well as extensive electrostatic interactions. Therefore, 1 can be a suitable choice as sorbent in the D-µSPE of antidepressant drugs from human plasma samples via appreciable adsorbate-adsorbent interactions. Determination of the extracted antidepressant drugs was conducted using high-performance liquid chromatography-ultraviolet (HPLC-UV), with calibration plots being linear in the concentration range 0.1-500 ng mL-1 for amitriptyline and nortriptyline, 0.2-500 ng mL-1 for imipramine, and 0.5-300 ng mL-1 for sertraline. The relative standard deviation (RSD) values were calculated for both intra-day and inter-day precision, and the RSD% values were in the range 3.9 to 5.2% and 4.6-5.4%, respectively. The limits of detection (LODs) was determined as 0.03-0.2 ng mL-1. Due to the good stability and reusability of the sorbent, the adsorption capacity had no obvious decrease after being used 20 times. Finally, the D-µSPE-HPLC-UV method was applied for the determination of antidepressant drugs in human plasma samples with recoveries of the analytes in the range 94.9 to 102%. The article describes the synthesis of a robust molybdenum-based coordination polymer, and its application as sorbent for dispersive micro solid-phase extraction of antidepressant drugs from human plasma samples.

Polyoxometalate-Based Frameworks as Adsorbents for Drug of Abuse Extraction from Hair Samples.

The linkage of molecular components into functional heterogeneous framework materials has revolutionized modern materials chemistry. Here, we use this principle to design polyoxometalate-based frameworks as high affinity adsorbents for drugs of abuse, leading to their application in solid-phase extraction analysis. The frameworks are assembled by the reaction of a Keggin-type polyanion, [SiW12O40]4-, with lanthanoids Dy(III), La(III), Nd(III), and Sm(III) and the multidentate linking ligand 1,10-phenanthroline-2,9-dicarboxylic acid (H2PDA). Their reaction leads to the formation of crystalline 1D coordination polymers. Because of the charge mismatch between the lanthanoids (+3) and the dodecasilicotungstate (-4), we observe incorporation of the PDA2- ligands into crystalline materials, leading to four polyoxometalate-based frameworks where Keggin-type heteropolyanions are linked by cationic {Lnn(PDA)n} groups (Ln = Dy (1), La (2), Nd (3), and Sm (4)). Structural analysis of the polyoxometalate-based frameworks suggested that they might be suitable for surface binding of common drugs of abuse via supramolecular interactions. To this end, they were used for the extraction and quantitative determination of four model drugs of abuse (amphetamine, methamphetamine, codeine, and morphine) by using micro-solid-phase extraction (D-µSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges, low limits of detection (0.1-0.3 ng mL-1), high precision, and satisfactory spiked recoveries. Our results demonstrate that polyoxometalate-based frameworks are suitable sorbents in D-µSPE for molecules containing amine functionalities. The modular design of these networks could in the future be used to expand and tune their substrate binding behavior.

Microcrystalline cellulose/metal-organic framework hybrid as a sorbent for dispersive micro-solid phase extraction of chlorophenols in water samples.

In this study, the microcrystalline cellulose/metal-organic framework 199 hybrid (MCC/MOF-199) was applied as sorbent for the dispersive micro-solid phase-extraction (D-µSPE) of chlorophenols. The D-µSPE method combined with high-performance liquid chromatography- ultraviolet detection (HPLC-UV) was employed to determine of four chlorophenols including 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,3-dichlorophenol (2,3-DCP), and 2,5-dichlorophenol (2,5-DCP) in aqueous. The main parameters of the D-µSPE process that influence the extraction (i.e. the amount of sorbent, elution condition, extraction time, and pH) were investigated and optimized. Based on the outputs, the presence of MCC on the surface of MOF-199 leads to improve the properties of MOF-199 and the MCC/MOF-199 has the highest sorption capacity, durability, and porosity in comparison with MCC and MOF-199. According to the validation study at the optimized conditions, the linearity for the analytes was achieved in the range from 0.1 to 200 ng mL-1 for 2-CP and 4-CP and 0.15 to 200 ng mL-1 for 2,3-DCP and 2,5-DCP with correlation coefficients between 0.9928 and 0.9965. The limits of detection calculated at S/N=3 were in the range of 0.03-0.05 ng mL-1. Besides, the relative standard deviations (RSDs) for three spiking levels (0.2, 10,100 ng mL-1) do not exceed 6.8% and extraction recoveries are between 81.0% and 88.3%. Finally, the D-µSPE-HPLC-UV method was successfully applied to the analysis of CPs in real water samples (mineral, river and wastewater samples) with good recoveries (95.8 to 99.5%) and satisfactory precisions (RSD < 6.8%).

Electrode designed with a nanocomposite film of CuO Honeycombs/Ag nanoparticles electrogenerated on a magnetic platform as an amperometric glucose sensor.

Here, an ultrasensitive non-enzymatic glucose sensor was fabricated using a facile and low price electro-deposition method. At first, thiol-functionalized magnetic nanoparticles cast onto the glassy carbon electrode (GCE) surface to provide a stable substrate with the high surface area. Then, CuO nanoparticles and Ag nanoparticles electrodeposit on the surface of Fe3O4-SH/GCE to obtain the final modified GCE. The characterization of electro-synthesized nanoparticles and the modified GCE was done by different related techniques such as field emission scanning electronic microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed electrode was applied to the electrochemical sensing of glucose. By employing the optimum conditions on the preparation of modified electrode such as time and potential for electrosynthesis of two different nanoparticles, high reproducibility of measurement and sensor preparation were achieved. The thus optimized simple glucose sensor could be provided stable responses in a wide linear range from 0.06 to 1000 µM with detection limit 15 nM, indicating its potential application for real biological samples.

Effective extraction of organophosphorus pesticides using sol-gel based coated stainless steel mesh as novel solid-phase extraction sorbent.

In this study, for the first time, stainless steel meshes coated with poly(ethylene glycol) and carbon nanotubes (PEG-CNT) by sol-gel technique were used as the adsorbent for solid-phase extraction. The coated stainless steel is loaded onto a cartridge and used to isolate and extract organophosphorus pesticides (OPPs) from water and fruit juice samples. Effective extraction parameters such as sample volume, desorption solvent, and desorption solvent volume were studied and investigated. Under optimal conditions, the linearity of the method was obtained in the range of 0.03 to 80 ng mL-1 and also the limits of detection (LODs) of the method were ranged from 0.01 to 0.03 ng mL-1. The repeatability of the method was evaluated at three concentration levels (0.1, 1, and 50 ng mL-1), and the relative standard deviation (RSD%) of the method was obtained in the range of 3.8 to 4.8%. Finally, the proposed method was used to analysis of OPPs in real water and fruit juice samples, with relative recovery in the range of 94.3 to 99.8%.

Graphene oxide/polydimethylsiloxane-coated stainless steel mesh for use in solid-phase extraction cartridges and extraction of polycyclic aromatic hydrocarbons.

The stainless steel mesh, in the form of the disk, was coated with graphene oxide and poly(dimethylsiloxane) (GO-PDMS) by sol-gel technique. The coated stainless steel meshes are loaded in the mini-column as solid-phase extraction cartridge for the fast isolation and preconcentration of polycyclic aromatic hydrocarbons (PAHs) from real water samples. The extracted PAHs (naphthalene, acenaphthene, acenaphthylene, anthracene, benz[a]anthracene, fluorene, and pyrene) were quantified by gas chromatography-mass spectrometry. The operation parameters affecting the extraction efficiency including sample volume, desorption conditions, and ionic strength were investigated. At optimized conditions, the linearity of this method is obtained from 0.001 to 20 ng mL-1 with 0.2 to 1.0 pg mL-1 limit of detection. For 5 replicates at 3 spiking levels (0.1, 1, and 10 ng mL-1), the relative standard deviations between 4.0 and 6.3% were achieved. The absolute extraction recovery varied from 89.1 to 94.7%. The enrichment factors were in the range of 2227-2367. The method has been employed in the determination of PAHs in the real water samples including well water, tap water, river water, and wastewater. Relative recoveries are between 95.2 and 100.9%. Graphical abstractSchematic representation of the SPE procedure using the self-assembly SPE cartridge.

A nanohybrid composed of polyoxotungstate and graphene oxide for dispersive micro solid-phase extraction of non-steroidal anti-inflammatory drugs prior to their quantitation by HPLC.

A nanohybrid was prepared from polyoxotungstate anion and graphene oxide (POT/GO) and characterized in terms of porosity by applying Fourier transform infrared and transmission electron microscopy. The nanohybrid was applied as a sorbent for the dispersive micro solid-phase extraction of the non-steroidal anti-inflammatory drugs (NSAIDs) ibuprofen, diclofenac, and naproxen. Different types of sorbents were compared, and the POT/GO nanohybrid was found to have the best adsorption affinity. The NSAIDs were quantified via HPLC with UV detection. Under the optimum conditions, the limits of detection (at an S/N ratio of 3) range between 0.02-0.03 ng.mL-1, and the linear response ranges extend from 0.08-200 ng.mL-1, respectively. The relative standard deviations (RSDs) for five replicates at three concentration levels (0.1, 5 and 100 ng.mL-1) of NSAIDs ranged from 4.1 to 6.1%. The applicability of the method was confirmed by analyzing spiked real water samples, and satisfactory results were obtained, with recoveries between 95.6 and 99.6%. Graphical abstract Schematic representation of the polyoxotungstate/graphene oxide nanohybrid preparation.