Dispersive Solid-phase Extraction Adsorbent Research Articles

Zeolitic imidazolate framework-8 as a high-affinity adsorbent for dispersive solid-phase extraction in the analysis of plant growth regulators in fruits.

Facile and sensitive determination of plant growth regulators (PGRs) in food samples is crucial but still poses a significant challenge. In this study, to enhance the sensitivity of the HPLC-DAD method for PGR detection, a dispersive solid phase extraction (d-SPE) method using zeolitic imidazolate framework-8 (ZIF-8) as the highly effective adsorbent is developed. ZIF-8 nanoparticles are formed through the coordination of Zn2+ with 2-methylimidazole. Due to its high porosity, large surface area, abundant π electronics and nitrogen electronics, ZIF-8 exhibits a strong affinity to PGRs due to the synergistic effects of π-π interaction, van der Waals force, H-bond, and surface effect. Under the optimal d-SPE conditions, the sensitivity of the method is significantly enhanced with outstanding performances, including a wide range of linearity (2.0-200 ng g-1) with high correlation coefficients (R ≥ 0.9989), low limits of detection (LODs, 0.9-8.0 ng g-1 for all PGRs), satisfactory precision (intra-day RSDs ≤ 3.3%, inter-day RSDs ≤ 4.2%), and high accuracy (recovery: 86.6-101.5%). The developed method was successfully applied to quantitatively detect 9 PGRs in fruit samples, yielding satisfactory results. This d-SPE-HPLC-DAD method, characterized by high sensitivity, simplicity, efficiency, ease of practice and cost-effectiveness for PGR detection, shows potential for detecting PGRs in other complex samples and provides a strategy for designing target-affinity adsorbents.

Porous poly(bismaleimide-co-divinylbenzene) microspheres as dispersive solid-phase extraction adsorbent coupled to high-performance liquid chromatography for the determination of triazine herbicide residues in vegetable samples.

In this work, monodisperse and nano-porous poly(bismaleimide-co-divinylbenzene) microspheres with large specific surface area (427.6 m2 /g) and rich pore structure were prepared by one-pot self-stable precipitation polymerization of 2,2'-bis[4-(4-maleimidophenoxy) phenyl] propane and divinylbenzene. The prepared poly(bismaleimide-co-divinylbenzene) microspheres were employed as dispersive solid-phase extraction (DSPE) adsorbent for the extraction of triazine herbicides. Under optimized conditions, good linearities were obtained between the peak area and the concentration of triazine herbicides in the range of 1-400µg/L (R2 ≥ 0.9987) with the limits of detection of 0.12-0.31µg/L. Triazine herbicides were detected using the described approach in vegetable samples (i.e., cucumber, tomato, and maize) with recoveries of 93.6%-117.3% and relative standard deviations of 0.4%-3.5%. In addition, the recoveries of triazine herbicides remained above 80.7% after being used for nine DSPE cycles, showing excellent reusability of poly(bismaleimide-co-divinylbenzene) microspheres. The adsorption of poly(bismaleimide-co-divinylbenzene) microspheres toward triazine herbicides was a monolayer and chemical adsorption. The adsorption mechanism between triazine herbicides and adsorbents might be a combination of hydrogen bonding, electrostatic interaction, and π-π conjugation. The results confirmed the potential use of the poly(bismaleimide-co-divinylbenzene) microspheres-based DSPE coupled to the high-performance liquid chromatography method for the detection of triazine herbicide residues in vegetable samples.

Preparation of modified multiwalled carbon nanotubes (l-Arg-CS/MWCNTs-COOH/Fe3O4) as sorbent for dispersive solid phase extraction of Cu(II), Pb(II) and Cd(II) in wastewater samples

A new modified multiwalled carbon nanotube (l-Arg-CS/MWCNTs-COOH/Fe3O4) as sorbent of dispersive solid phase extraction (DSPE) was synthesized for preconcentration and determination of Cu (II), Pb (II), and Cd (II) in wastewater samples. The successful formation of sorbent was characterized by FTIR (Fourier transform infrared) spectroscopy, SEM (Scanning electron microscope), and XRD (X-ray diffraction). Batch experiments such as solution pH, amount of adsorbent, extraction time, type and volume rate of eluent and etc were achieved to study the sorption process. At optimized conditions the adsorbent shows good recovery with 4mL ethylene diamine tetra acetic acid) EDTA( as eluent. Good fitting of sorption kinetics by pseudo-second-order model was obtained. Limits of detection were found in the range of 0.10-0.12 μg L−1 for metal ions, the liner range was 5-1000 μg L−1 for Cd(II) and 10-1000 μg L−1 for Cu(II) and Pb(II) and the preconcentration factor 60, 65 and 55 for Cu(II), Pb(II) and Cd(II), respectively. The relative standard deviation was in the range of 1.5-2.3 %. Results showed that the new magnetic nanosorbent was an efficient DSPE adsorbent for preconcentration and determination of Cu (II), Pb (II), and Cd (II) in wastewater samples.

Reduced graphene oxide-zinc iron oxide nanomaterial as selective dispersive solid-phase extraction sorbent for extraction and enrichment of aflatoxins from milk combined with UHPLC-MS/MS analysis

Fungal species capable of producing aflatoxins frequently contaminate the feed provided to dairy animals, leading to the subsequent occurrence of aflatoxin contamination in milk. Milk is renowned for its exceptional nutritional composition, and the consumption of milk contaminated with aflatoxins by humans can engender a multitude of health complications. In this study, reduced graphene oxide zinc iron oxide (rGO-Zn/Fe2O4) nanomaterial was utilized as a dispersive solid phase extraction adsorbent to separate and enrich aflatoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, and aflatoxin M1) from milk. The rGO-Zn/Fe2O4 nanomaterial was morphologically characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, indicating that Zn/Fe2O4 nanoparticles were embedded on the surface of rGO. The acetonitrile/formic acid (99/1, v/v) combined with ultrasonic treatment for a duration of 40 min expressed an efficient extraction solvent. Employing the matrix-spiked technique, different parameters of the dispersive solid-phase extraction (d-SPE) method were meticulously optimized, yielding the following conditions: 2% acetonitrile as loading solvent, 15 mg of rGO-Zn/Fe2O4 as the adsorbent quantity, 15 min of ultrasonication as adsorption time, and n-hexane as the washing solvent. The desorption reagent was 5 mL acetonitrile, with a desorption time of 5 min. The combination of the dispersive solid-phase extraction (d-SPE) technique with validated UHPLC-MS/MS quantitative analysis demonstrated excellent selectivity, a robust linear relationship (R2 ≥ 0.994), remarkable sensitivity (limit of quantification ranging from 0.006 to 0.013 µg/L), and satisfactory recovery rates of 78%–104% at three different matrix-spiked levels. Moreover, the method exhibited precision with relative standard deviations (RSD) ranging from 2.4% to 10.8%. Following appropriate pretreatment procedures, the milk samples underwent rigorous aflatoxin analysis, leading to the identification of AFM1 presence in all of the examined milk samples (n = 9). However, the contamination levels detected were found to be within the permissible limits as defined by regulatory standards.

Facile synthesis of spherical covalent organic frameworks for enrichment and quantification of aryl organophosphate esters in mouse serum and tissues.

Here, an imine-linked-based spherical covalent organic framework (COF) was prepared at room temperature. The as-synthesized spherical COF served as an adsorbent in dispersive solid-phase extraction (dSPE), by its virtue of great surface area (1542.68 m2 /g), regular distribution of pore size (2.95nm), and excellent stability. Therefore, a simple and high-efficiency dispersive solid phase extraction method based on a spherical COF coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established to determine aryl organophosphate esters in biological samples. This approach displayed favorable linearity in the range of 10.0-1000.0ng/L (r>0.9989), a high signal enhancement factor (58.8-181.8 folds) with low limits of detection (0.3-3.3ng/L). Moreover, it could effectively eliminate complex matrix interference to accurately extract seven aryl organophosphate esters from mouse serum and tissue samples with spiked recoveries of 82.0%-117.4%. The as-synthesized spherical COF has been successfully applied in sample preparation. The dSPE-HPLC-MS/MS method based on a spherical COF has potential application to study the pollutants' metabolism in vivo.

Slice-layer COFs-aerogel: a regenerative dispersive solid-phase extraction adsorbent for determination of ultra-trace quinolone antibiotics.

A novel type of three-dimensional network structure, covalent organic frameworks (COFs) aerogel, was fabricated and applied to dispersive solid-phase extraction (dSPE) of quinolone antibiotics (QAs). Density functional theory (DFT) was applied to investigate the possible interaction mechanism and results confirmed that the strong adsorption affinity is attributed to the intralayer hydrogen bonds and π-π interaction. Furthermore, a sensitive analytical method based on COFs-aerogel for determining quinolone antibiotics residues in water and honey samples was developed and HPLC-MS/MS was used for sample detection and quantification. Under the optimal conditions, COFs-aerogel exhibited a wide linearity (0.1-500 ng∙L-1), low limits of detection (0.02-0.06 ng∙L-1), and good precision (RSD ˂ 10%) for selected QAs. A preliminary practical application of the developed method was proved by the efficient detection of quinolone antibiotics in water and food samples with good recoveries (68.2-104% and 64.0-100% for water and honey samples, respectively). Combining the experimental data with theoretical calculation, results illustrated that COFs-aerogel holds a great potential to capture contaminants and address environmental and food safety issues.

Application of Diphenyl Functionalization of Nickel Foam as Dispersive Solid-Phase Extraction Adsorbent to Polycyclic Aromatic Hydrocarbon Contaminants in Chinese Herbal Medicines

Application of Diphenyl Functionalization of Nickel Foam as Dispersive Solid-Phase Extraction Adsorbent to Polycyclic Aromatic Hydrocarbon Contaminants in Chinese Herbal Medicines

Efficient fabrication of pH-modified graphene nano-adsorbent for effective determination and monitoring of multi-class pesticide residues in market-fresh vegetables by GC-MS

Toxic pesticide residues in edible vegetables cause major health risks for consumers, hence quantifying them is essential. However, simultaneous and trace level determination of xenobiotic residues of various classes in complex food matrices is still a challenging analytical task. In this experiment, reduced graphene oxide (RGO-B), a carbon nano-structure with stunning adsorbent properties and ultrahigh surface area (pore size ∼6 Å) was efficiently (≥96%) synthesized via pH-controlled reduction process and characterized by ultraviolet-visible (UV–VIS) spectrophotometer, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Fourier Transform Infrared (FTIR). Adsorption efficiency of different pH-regulated RGOs was studied in terms of dye (Malachite Green) removal percentage. Two-dimensional carbon (sp2) RGO was used as a dispersive solid-phase extraction adsorbent in a modified QuEChERS method in combination (4:1) with primary secondary amine (PSA) to extract 28 multi-class pesticides (OC, OP, SP) from chilli, cabbage, tomato, and cucumber. The experimental results established the best extraction ability and adsorption capacity of RGO over traditional and high-cost adsorbents. Moreover, the introduction of graphene has helped improve the percent recovery (75.36–118.32%) with acceptable (<12.8%) relative standard deviation (RSD) at limits of quantification (LOQs) (S/N = 10:1) levels of 0.01–0.1 mgL−1. Gas chromatography-mass spectrometry (GC-MS)-based multi-pesticide analytical method was successfully validated as per SANTE/12682/2019 guidelines for monitoring 144 market-fresh vegetables in West Bengal, India. The analysis results indicated that eight (8) samples (5.55%) were contaminated with toxicants 5–10 times higher than the European Union Maximum Residue Limits (EU-MRLs). Matrix removal abilities and cost analysis proved that graphene has significant prospects as an expectant non-conventional adsorbent for low-cost (53.3% cheaper) pesticide residue analysis.

Magnetic cork composites as biosorbents in dispersive solid-phase extraction of pesticides in water samples.

This study assessed the use of magnetic biosorbents in dispersive solid-phase extraction with a gas chromatograph-electron capture detector for the determination of trifluralin, chlorothalonil, transfluthrin, bromopropylate, and bifenthrin in water samples. To our knowledge, this is the first time that magnetic cork composites are used as an adsorbent in dispersive solid-phase extraction. The advantages of magnetic cork composites include their density regulation and high surface areas. The magnetic composites can be recovered using a magnetic field for desorption purposes, which can improve the operation process and reduce the extraction time. Moreover, the parameters affecting the extraction performances were optimized. The method has a limit of detection between 0.30 and 2.02 μg L-1. Good linearities (R2 > 0.99) were obtained in the linear range of 1.00 to 2000 μg L-1. The relative recoveries of the analytes in tap water, river, and lake water samples spiked at different concentrations ranged between 90% and 104%, and the relative standard deviations were less than 7.1%. Therefore, this study showed that Fe3O4/cork magnetic composites can be used as efficient and eco-friendly biosorbents in dispersive solid-phase extraction for the determination of pesticides in water samples. The use of these composites contributes to the current trend of green chemistry.

Ant nest-like hierarchical porous imprinted resin-dispersive solid-phase extraction for selective extraction and determination of polychlorinated biphenyls in milk

Polychlorinated biphenyls (PCBs) are persistent toxic, organic chemicals that tend to accumulate in the food chain. This study reports the rapid and selective extraction and determination of PCBs (PCB81, 153, 105, 126, and 157) in milk samples by a dispersive solid-phase extraction (DSPE) coupled with gas chromatography-tandem mass spectrometry (GC–MS/MS). An ionic liquid-molecularly imprinted porous resin (IL-MIPPR) as a DSPE adsorbent was synthesized from m-aminophenol, formaldehyde, and 2,2′-benzidinedisulfonic acid as the monomer, crosslinker, and virtual template, respectively. The IL-MIPPR had a fast mass transfer (1.0 min) and good selectivity (imprinting factors of 1.8–3.0). The IL-MIPPR − DSPE − GC–MS/MS method exhibited good linearity (R2 ≥ 0.9995), the limit of detections (LODs) < 0.6 pg/g, and the recoveries ranged from 82.8 % to 106 % with relative standard deviations ≤ 6.6 %. This method is thus better than previously reported methods in terms of the LOD, the adsorbent dosage, and the extraction time.

NiO/ZnO-Coated Carbon Microspheres for Dispersive Solid-Phase Extraction (DSPE) of Malachite Green and Crystal Violet in Aquatic Food Products with Determination by Ultra-High-Performance Liquid Chromatography (UPLC)

Developing highly efficient adsorbents toward trace pollutant analysis in complex biological samples is a challenge in analytical chemistry. Herein, NiO/ZnO-coated carbon microspheres (denoted by NiO/ZnO@C) with a well-defined core–shell structure were prepared through hydrothermal treatment and subsequent pyrolysis in air to enrich malachite green (MG) and crystal violet (CV). Hydrophilic carbon microspheres played an important role in the formation of core–shell NiO/ZnO@C, which may lead to the deposition of Ni2+/Zn2+ upon the surface via acidic chelating ligands. Based on the Langmuir model, NiO/ZnO@C demonstrated high adsorption capacities of 333.3 and 192.3 mg/g for MG and CV, respectively. Moreover, the NiO/ZnO@C composite served as a dispersive solid-phase extraction adsorbent to determine MG and CV in aquatic products combined with ultra-high performance liquid chromatography. High linearity was obtained for analyte concentrations from 5 to 500 μg/L with correlation coefficients (r) exceeding 0.9991. The limits of detection of the method were 0.50 μg/L (MG) and 0.35 μg/L (CV) with relative standard deviations less than 7.47%. Furthermore, the developed method was employed to determine MG and CV in aquatic products.

Covalent Organic Framework/Polyacrylonitrile Electrospun Nanofiber for Dispersive Solid-Phase Extraction of Trace Quinolones in Food Samples.

The extraction of quinolone antibiotics (QAs) is crucial for the environment and human health. In this work, polyacrylonitrile (PAN)/covalent organic framework TpPa–1 nanofiber was prepared by an electrospinning technique and used as an adsorbent for dispersive solid-phase extraction (dSPE) of five QAs in the honey and pork. The morphology and structure of the adsorbent were characterized, and the extraction and desorption conditions for the targeted analytes were optimized. Under the optimal conditions, a sensitive method was developed by using PAN/TpPa–1 nanofiber as an adsorbent coupled with high-performance liquid chromatography (HPLC) for five QAs detection. It offered good linearity in the ranges of 0.5–200 ng·mL−1 for pefloxacin, enrofloxacin, and orbifloxacin, and of 1–200 ng·mL−1 for norfloxacin and sarafloxacin with correlation coefficients above 0.9946. The limits of detection (S/N = 3) of five QAs ranged from 0.03 to 0.133 ng·mL−1. The intra-day and inter-day relative standard deviations of the five QAs with the spiked concentration of 50 ng·mL−1 were 2.8–4.0 and 3.0–8.8, respectively. The recoveries of five QAs in the honey and pork samples were 81.6–119.7%, which proved that the proposed method has great potential for the efficient extraction and determination of QAs in complex samples.

Progress in preparation of plant biomass-derived biochar and application in pesticide residues field

随着农药的广泛使用,其已普遍存在于环境中,对人们的身体健康产生巨大影响。因此,环境中农药残留的去除和分析检测对保护人体安全健康至关重要。同时,农药在环境中残留浓度低,需要一种对目标物有较强选择性和富集作用,并对环境影响小的前处理吸附剂。植物源生物炭是由植物源生物质作为碳源衍生得到的材料,其比表面积大、孔容量高、表面官能团可调节,且环境相容性好,其原料植物源生物质的价格低廉、来源广泛并可再生,是一种廉价高效的吸附剂。该文主要综述了近10年来植物源生物炭用于环境中农药残留去除和分析检测前处理的应用进展。其中在农药残留去除方面的应用主要包括降低农药在土壤中的移动性,修复手性农药造成的污染,负载降解农药的细菌及作为化肥的缓释载体。在农药残留分析检测前处理方面,植物源生物炭可用作分散固相萃取、固相微萃取和磁性固相萃取的吸附剂来选择性吸附水果和蔬菜中的有机磷类和三唑类农药,以及水环境中的有机氯类农药。另外,还介绍了植物源生物炭的吸附机理,详细阐述了基于计算模拟如密度泛函理论、分子动力学模拟和巨正则蒙特卡洛模拟的吸附机理研究并讨论了其优势。最后,总结了植物源生物炭在农药去除和农药残留分析检测前处理方面应用的优势,指出了其在农药残留领域应用待解决的问题。

In-situ sorbent formation for the extraction of pesticides from honey.

An organic polymer was re-precipitated in solution to use as an adsorbent in dispersive solid-phase extraction of some pesticides from honey samples prior to their determination by high-performance liquid chromatography-tandem mass spectrometry. In this approach, different deep eutectic solvents were prepared using lysine and their ability in elution of the analytes from the adsorbent surface was tested. A diluted honey solution was transferred into a glass test tube and then a solution of polystyrene dissolved in dimethylformamide was injected into the solution. By doing this, polystyrene is re-precipitated in the solution and dispersed in whole parts of it as many tiny particles. Then the mixture was centrifuged and the adsorbed analytes on the particles were eluted using a proper hydrophilic deep eutectic solvent. The central composite design approach was used for the optimization of effective parameters. The limits of detection and quantification were in the ranges of 0.06-0.20 and 0.22-0.69ng/g, respectively. The calibration curves obtained by matrix-matched standard solutions were linear in the range of 0.69-500ng/g with a coefficient of determinations ≥0.9962. The method provided high extraction recoveries (70-99%) and enrichment factors (140-198), and an acceptable precision (relative standard deviations ≤7.1%).

Dual-Template Magnetic Molecularly Imprinted Polymer for Simultaneous Determination of Spot Urine Metanephrines and 3-Methoxytyramine for the Diagnosis of Pheochromocytomas and Paragangliomas.

A novel dual-template magnetic molecularly imprinted polymer (MMIP) was synthesized to extract normetanephrine (NMN), metanephrine (MN) and 3-methoxytyramine (3-MT) from spot urine samples. As the adsorbent of dispersive solid-phase extraction (d-SPE), the MMIP was prepared using dopamine and MN as dual templates, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the crosslinking reagent and magnetic nanoparticles as the magnetic core. NMN, MN, 3-MT and creatinine (Cr) in spot urine samples were selectively enriched by d-SPE and detected by HPLC-fluorescence detection/ultraviolet detection. The peak area (A) ratios of NMN, MN and 3-MT to Cr were used for the diagnosis of pheochromocytomas and paragangliomas (PPGLs). The results showed that the adsorption efficiencies of MMIP for target analytes were all higher than 89.0%, and the coefficient variation precisions of intra-assay and inter-assay for the analytes were within 4.9% and 6.3%, respectively. The recoveries of the analytes were from 93.2% to 112.8%. The MMIP was still functional within 14 days and could be reused at least seven times. The d-SPE and recommended solid-phase extraction (SPE) were both used to pretreat spot urine samples from 18 PPGLs patients and 22 healthy controls. The correlation coefficients of ANMN/ACr and AMN/ACr between d-SPE and SPE were both higher than 0.95. In addition, the areas under the receiver operator curves for spot urine ANMN/ACr, AMN/ACr and plasma free NMN and MN were 0.975, 0.773 and 0.990, 0.821, respectively, indicating the two methods had the similar performances. The d-SPE method took only 20 min, which was effective in clinical application.

Use of hydroxypropyl β-cyclodextrin hybrid monolithic material as adsorbent for dispersive solid-phase extraction of fluoroquinolones from environmental water samples.

In this study, the hydroxypropyl β-cyclodextrin hybrid monolithic material was fabricated and firstly applied as an adsorbent for dispersive solid-phase extraction coupled with high-performance liquid chromatography to detect trace-level seven fluoroquinolones in water samples. The prepared hydroxypropyl β-cyclodextrin hybrid monolithic material was characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and adsorption experiments, which showed excellent specific adsorption to the target fluoroquinolones. Under the optimized conditions, the extraction methodology showed satisfactory precision with relative standard deviations between 2.6% and 5.6%, good linearity (R2 ≥0.9990), and satisfactory recoveries (82.5-91.8%). The limits of detection and limits of quantification of the method were in the range of 0.4-1.2 and 1.4-4.0 ng/mL, respectively, which confirmed the possibility of quantifying trace levels. Furthermore, the material could be reused at least five times. These results demonstrated that the hydroxypropyl β-cyclodextrin hybrid monolithic material was a promising adsorbent for fluoroquinolones, and the established method combined dispersive solid-phase extraction with high-performance liquid chromatography was suitable for the determination of fluoroquinolones in aqueous samples.

Application of β-Cyclodextrin metal-organic framework/titanium dioxide hybrid nanocomposite as dispersive solid-phase extraction adsorbent to organochlorine pesticide residues in honey samples

A simple and efficient dispersive solid-phase extraction (D-SPE) method combined with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed to determine organochlorine pesticides (OCP) in honey. Firstly, a type of hybrid nanocomposite (CD-MOF/TiO2) was prepared by grafting a metal-organic framework material synthesized with cyclodextrin as an organic ligand onto titanium dioxide. Then, the CD-MOF/TiO2 was used as a D-SPE adsorbent to extract the OCP, and the effects of the amount of adsorbent, ultrasonic time, vortex time, pH, and salinity on the extraction were investigated using Plackett–Burman design and Box-Behnken Design. Under the optimized adsorption and desorption conditions, an analysis method that combined D-SPE with GC-MS/MS was established. The linear ranges of 14 OCP are 1–500 μg kg−1 and the correlation coefficients are between 0.9991 and 1.000. The limits of detection and quantification vary from 0.01 to 0.04 μg kg−1 and 0.04 to 0.12 μg kg−1, respectively. The intra-day and inter-day precision of this method are suitable (RSDs% less than 11.3%). The established CD-MOF/TiO2 / D-SPE method was used for the extraction of OCP in honey samples with recovery in the range of 76.4 to 114.3%. The results demonstrate that the CD-MOF/TiO2 has a good selective enrichment ability for OCP and is suitable for the D-SPE pretreat of honey sample analysis.

Graphene oxide composite microspheres as a novel dispersive solid-phase extraction adsorbent of bisphenols prior to their quantitation by HPLC–mass spectrometry

Novel graphene oxide on polystyrene microspheres were fabricated via layer-by-layer assembly and initially applied to extract four bisphenol endocrine disruptors (bisphenol A, bisphenol B, bisphenol AF, tetrabromobisphenol A) in various environmental water samples following high performance liquid chromatography-tandem mass spectrometry determination. The as-synthesized adsorbent was then applied for dispersive solid-phase extraction. The as-prepared GO@PS was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Furthermore, the main parameters governing the extraction efficiency were optimized in detail, and under the optimized conditions, attractive results were obtained. The developed method exhibited high enrichment factors ranging from 73 (BPB) to103 (BPA), low detection limits (0.02–0.11 μg·L−1) and wide linear ranges (0.1–1000 μg·L−1) for enriching and detecting the four bisphenol endocrine disruptors. Meanwhile, acceptable results were obtained when the developed technique was used to determine four target pollutants in real water samples, with spiked recoveries in the range of 71.1%–104.8%. This indicated that GO@PS was a powerful material for the enrichment and determination of bisphenols in complex matrices.

Biomass-Derived Adsorbent for Dispersive Solid-Phase Extraction of Cr(III), Fe(III), Co(II) and Ni(II) from Food Samples Prior to ICP-MS Detection

A biomass-derived adsorbent was simply prepared and applied as efficient and low-cost solid-phase supports. The adsorbent material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), surface area analysis and Fourier transform infrared (FTIR) spectroscopy. The amorphous structure of the prepared adsorbent was indicated from the XRD. The prepared adsorbent exhibited surface functional groups such as carbonyl and hydroxyl groups, which enhance the application of DSPE. An accurate separation and preconcentration of Cr(III), Fe(III), Co(II) and Ni(II) prior to ICP-MS detection was achieved using the biomass-derived adsorbent. The extraction process was performed at pH 4 using 1 mL of 0.5 N nitric acid for elution and recovery of ions. The prepared biomass-derived adsorbent showed efficient performance for extraction application, exhibiting a preconcentration factor of 50 and LODs of 1.4, 2.4, 1.9 and 3.0 µg.L−1 for Cr(III), Fe(III), Co(II) and Ni(II), respectively, while the LOQs were reported as 4.1, 7.3, 5.7 and 8.9 µg.L−1 for Cr(III), Fe(III), Co(II) and Ni(II), respectively. The DSPE procedure presented was successfully applied to the determination of the Cr(III), Fe(III), Co(II) and Ni(II) contamination in some food samples.

Determination of seven phenoxy acid herbicides in water by dispersive solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on cationic metal-organic framework mixed matrix membrane

离子型金属有机骨架材料(iMOFs)对离子型化合物具有良好的选择吸附性,利用水热法合成了一种金属有机骨架材料MIL-101-NH2,以聚偏二氟乙烯(PVDF)为交联剂将其制备成混合基质膜(MMM),然后用三氟甲烷磺酸甲酯进行季胺基功能化改性,最终得到阳离子型金属有机骨架膜材料MIL-101-$NMe_{3}^{+}$-PVDF MMM,采用分散固相萃取方式富集水中的苯氧羧酸类除草剂,建立了一种基于阳离子型MOF混合基质膜的分散固相萃取-超高效液相色谱-串联质谱(UPLC-MS/MS)测定水体中7种苯氧羧酸类除草剂的分析方法。通过傅里叶变换红外光谱和扫描电子显微镜对制备的混合基质膜进行表征,结果表明季胺基功能化改性是成功的,得到了阳离子型MOF膜。对影响萃取效果的主要因素(吸附剂用量、水样pH值、萃取时间、洗脱剂种类、洗脱剂体积及洗脱时间)进行了优化,确定了最佳萃取条件。以0.01%(v/v)甲酸水溶液和乙腈作为流动相进行梯度洗脱,目标化合物在ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)上分离,在电喷雾电离源、负离子模式下进行多反应监测(MRM),外标法定量。结果表明,7种苯氧羧酸类除草剂在各自范围内线性关系良好,线性相关系数均大于0.997,方法的检出限(LOD)和定量限(LOQ)分别为0.00010~0.00090 μg/L和0.00033~0.00300 μg/L。在0.005、0.05和0.2 μg/L 3个加标水平下进行加标回收率试验,7种待测物的平均回收率为80%~102%,日内、日间相对标准偏差分别为1.4%~9.4%和4.2%~12.6%。该方法操作简单、快速,灵敏度高,适用于环境水体中7种苯氧羧酸类除草剂的检测。