Solid-phase Extraction Material Research Articles

Magnetic partially carbonized cellulose nanocrystal-based magnetic solid phase extraction for the analysis of triazine and triazole pesticides in water.

Magnetic partially carbonized cellulose nanocrystals (MPC-CNC) were obtained by sulfuric acid treatment of microcrystalline cellulose (MCC) and then loaded with magnetic Fe3O4 nanoparticles. The material is shown to be a viable material for magnetic solid phase extraction of triazine and triazole pesticides from water. The pesticides (specifically: simazine, ametryn, prometryn, terbutryn, atrazine, triadimenol, epoxiconazole, myclobutanil, triadimefon and tebuconazole) were quantified by ultra HPLC in tandem with a triple quadrupole mass spectrometry (UHPLC-MS/MS). The effects of NaCl concentration, amount of adsorbent, vortex time, sample volume and pH value on extraction efficiency were optimized by Plackett-Burman design and Box-Behnken design methods. Under the optimal conditions, the method shows the following figures of merit: (a) Linear responses in the range from 0.02-10μgL-1; (b) detection limits between 2.2 to 6.1ngL-1 (for S/N = 3); (c) recoveries from spiked samples of 73.7-117.1% with relative standard deviations (RSDs) of 2.0-15.7%; and (d) an enrichment factor of 75. The method was successfully applied to the determination of the pesticides in five environmental water samples. Graphical abstract Schematic representation of the process of magnetic solid phase extracting pesticides in water using MPC-CNC. MCC-microcrystalline cellulose; PC-CNC- partially carbonized cellulose nanocrystals; MPC-CNC-magnetic partially carbonized cellulose nanocrystals.

Green synthesis of magnetic carbon nanodot/graphene oxide hybrid material (Fe3O4@C-nanodot@GO) for magnetic solid phase extraction of ibuprofen in human blood samples prior to HPLC-DAD determination

In this study, a green production method was used to obtain magnetic carbon nanodot/graphene oxide hybrid material (Fe3O4@C-nanodot@GO) for the magnetic solid phase extraction (MSPE) of ibuprofen (IBU) in human plasma prior to HPLC-DAD determination. For the first time in the literature, Fe3O4@C-nanodot@GO hybrid material was synthesized and used as an adsorbent. C-nanodots were produced from pasteurized cow milk by using a simple and cheap hydrothermal method. After production of the C-nanodots and GO, Fe3O4@C-nanodot@GO hybrid material was fabricated in green solvent medium by using an one-step hydrothermal method. The method was based on the simple separation, preconcentration and analysis of ibuprofen by using MSPE-HPLC-DAD combination. The concentration changes of ibuprofen in human bloods against time were successfully monitored by using this combined method. For this purpose, blood samples were taken from volunteers at certain intervals after the administration of a certain dose of ibuprofen, and the MSPE method was used to monitor the concentration changes of ibuprofen in the blood samples. Experimental variables affecting the extraction efficiency of IBU such as sample solution pH, amount of adsorbent, extraction time, eluent type and volume were studied and optimized in the details. The characterization studies for the Fe3O4@C-nanodot@GO were carried out by X-ray diffraction spectrometry (XRD), Fourier transform infrared spectrometry (FT-IR), Raman spectrometry (Raman), energy dispersive x-ray (EDX), vibrating sample magnetometry (VSM) and scanning electron microscopy (SEM) techniques. Under the optimum experimental conditions, the limit of detection (LOD) was 8.0 ng mL−1 and the recoveries at three spiked levels in human plasma were ranged from 91.0% to 95.0% with the relative standard deviation (RSD %) less than 4.0 % (n = 6). The results show that together use of MSPE with HPLC-DAD provides a simple and rapid analysis of ibuprofen in human plasma samples.

Polycaprolactone nanofibers functionalized with adopamine coating for on-line solid phase extraction of bisphenols, betablockers, nonsteroidal drugs, and phenolic acids.

Polycaprolactone composite nanofibers coated with a polydopamine layer are introduced as a new type of absorption material for on-line solid phase extraction (SPE) in chromatographic system. A hybrid technology combining the electrospinning and melt blowing was used for the preparation of 3D-structured microfiber/nanofibrous polycaprolactone composite. The dopamine coating was then applied to functionalize the micro/nanofibers. Polydopamine-coated polycaprolactone fibers were tested as an extraction phase in on-line SPE prior to HPLC separation and UV detection. Four groups of biologically active substances including bisphenols (Bisphenol S, Bisphenol AF, Bisphenol A, Bisphenol C, Bisphenol AP, Bisphenol Z, Bisphenol BP, and Bisphenol M), betablockers (Timolol, Metoprolol, Labetalol, and Propranolol), nonsteroidal antiphlogistic drugs (Salicylic acid, Ketoprofen, Naproxen, Indomethacin, Diclofenac, Ibuprophen, and Meclofenamic acid), and phenolic acids (Chlorogenic acid, Caffeic acid, Sinapic acid, m-Coumaric acid, Benzoic acid, and Cinnamic acid) were used as the model analytes. Neat and coated fibers were compared and applied as sorbents for the on-line extraction set-up. Both materials produced good extraction potential for the determination of bisphenols and nonsteroidal drugs in model biological and environmental samples including river water, human urine, and blood serum. However, the polydopamine layer significantly increased the extraction efficiency of polar drugs. Typical repeatability of on-line extraction procedure on polydopamine coated fibers was in the range 0.12-4.11% for bisphenols, 0.55-1.41% for antiphlogistic drugs, 0.59-2.52% for phenolic acids, and 1.01-1.65% for betablockers. Graphical abstract Schematic representation of polycaprolactone composite nanofibers coated with a polydopamine layer as an advanced absorption material for on-line solid phase extraction in chromatography.

Development of a sensitive analytical method for determining 44 pyrrolizidine alkaloids in teas and herbal teas via LC-ESI-MS/MS

Pyrrolizidine alkaloids (PA) and PA-N-oxides (PANO) are a large group of secondary plant metabolites comprising more than 660 compounds. Exhibiting geno- and hepatotoxic properties, they are responsible for multiple cases of food and feed poisoning over the last 100years. For food and feed safety reasons, relevant PA/PANO should be monitored extensively in the main sources of PA/PANO intake. In this study, a sensitive analytical method was developed for detecting a broad range of 44 commercially available PA/PANO compounds, and in-house validation procedures were performed for several (herbal) teas. Various extraction solvents and procedures, as well as solid phase extraction materials for sample clean-up and analyte concentration, were tested to establish the methods' efficiency and effectiveness. Chromatographic conditions were optimised to obtain the best possible separation of isomers for the 44 PA/PANO analytes. The final method was proven very sensitive and accurate, with detection limits ranging from 0.1 to 7.0μg/kg and precisions between 0.7 and 16.1%. For 40 of the analytes, the recovery rates ranged from 60.7 to 128.8%. The applicability and trueness of the method were examined by analysing tea samples from a local supermarket and comparing them to a reference material. At least one PA/PANO analyte was detected in 17 of the 18 samples under investigation, and the sum contents of the samples ranged from 0.1 to 47.9μg/kg. Knowledge of the PA/PANO composition in a sample can be used to indicate the botanical origin of the impurity and, thus, the geographical region of cultivation.

Tailorable yolk-shell Fe3O4@graphitic carbon submicroboxes as efficient extraction materials for highly sensitive determination of trace sulfonamides in food samples

A well-designed yolk-shell Fe3O4@graphitic carbon (YS-Fe3O4@GC) submicroboxes with a tunable internal cavity were constructed by one-step pyrolysis strategy followed by partially etching, in which the Fe3O4 magnetic core was well confined in compartment of GC submicroboxes. The suitable internal cavity, graphitic carbon shell and large specific surface area, play great roles in improving mass transfer of analytes. Compared to its core-shell structure, the YS-Fe3O4@GC submicroboxes as dispersive magnetic solid-phase extraction (d-MSPE) materials exhibited superior enrichment performance for sulfonamides (SAs). Thus, it was applied to sensitive/simultaneous detection of trace SAs in milk and meat samples, combing with high performance liquid chromatography (HPLC). Under optimized conditions, limits of detection (LODs, 0.11–0.25 μg L−1 for milk and 0.46–2.24 μg kg−1 for meat) and recoveries (77.2–118.0%) were obtained. This work not only offers a facile strategy for the tunable fabrication of yolk-shell architecture, but also successfully affords its exploration as d-MSPE materials.

Functionalized melamine sponge based on β-cyclodextrin-graphene oxide as solid-phase extraction material for rapidly pre-enrichment of malachite green in seafood

Functionalized melamine sponge based on β-cyclodextrin (β-CD) and graphene oxide (GO) as a new solid phase extraction (SPE) adsorbent, was developed for determination of malachite green (MG) in seafood, coupled with high-performance liquid chromatography (HPLC). The obtained sponge prepared by an easy method and simple step, is placed into a syringe to enrich quickly MG. The extraction procedure was further improved by investigating the effects of the experimental parameters on pre-enrichment of MG. The present method had been successfully applied to determination of MG from crayfish and squid sample and obtained satisfied recovery value (88.6–100.8%) with coefficient of variance below 2.6–9.2% (n = 3), which indicated that the method was suitable for the analysis of MG in complex samples. The method displayed good linear relationship in the concentration range of 0.5–20 μg mL−1 (R2 > 0.99), the low limit of detection of 0.21 mg L−1 and 1.0 mg kg−1 for food samples. Therefore, the β-CD-GO/MeS material has great application potential in the area of pre-concentration of complex matrix.

Counteracting in Vitro Toxicity of the Ionophoric Mycotoxin Beauvericin-Synthetic Receptors to the Rescue.

Beauvericin (BEA) and enniatins are toxic ionophoric cyclodepsipeptides that mainly occur in grains. As such, their presence in food commodities poses a concern for public health. To date, despite recent European Food Safety Authority emphasis on the need for more data to evaluate long-term toxicity effects, no suitable affinity reagents are available to detect the presence of BEA and derivatives in food samples. We here report on the synthesis of a small library of artificial receptors with varying cavity sizes and different hydrophobic building blocks. Immobilization of one of the receptors on solid support resulted in a strong retention of beauvericin, thus revealing promising properties as solid-phase extraction material for sample pretreatment. Furthermore, treatment of HepG2 cells with the most promising receptor markedly reduced beauvericin-induced cytotoxicity, hinting toward the possibility of using synthetic receptors as antidotes against ionophoric toxins.

Magnetically responsive materials for solid phase extraction

Magnetically responsive materials have found many important applications in analytical chemistry. In this short review the basic information about Magnetic solid phase extraction and Magnetic textile solid phase extraction is given. These analytical techniques enable to preconcentrate target biologically active compounds or pollutants from water samples. Both procedures enable to lower the limit of detection using conventional analytical procedures.

Study of solvent effect on the synthesis of magnetic molecularly imprinted polymers based on ultrasound probe: Application for sulfonamide detection.

In this work, a comparative study of the effect of various solvents on the synthesis of magnetic molecularly imprinted polymers (MMIPs) based on the use of high-power ultrasound probe is reported for the first time. Dimethylsulfoxide (DMSO), dimethylformamide (DMF), ethanol, acetonitrile and acetone were studied as solvents for the synthesis of MMIPs. Several crucial experimental conditions such as the time of synthesis and the applied amplitude were investigated. DMSO, DMF and ethanol were successfully used for ultrasound-assisted synthesis of MMIPs. However, for the polymerization performed using acetonitrile and acetone, no significant conversion to product was observed. Under optimal conditions for each solvent tested, the synthesized MMIPs were characterized using several techniques such as Scanning/Transmission Electron Microscopy (SEM and STEM modes), X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy, Thermal Gravimetric Analysis and Vibrating Sample Magnetometer system. The study of adsorption time of MMIPs showed that fast adsorption occurred due to the presence of specific imprinted sites on the surface. Moreover, isotherm study showed that the experimental equilibrium data fitted well with Freundlich model. The results of selectivity study indicated that MMIPs could selectively recognize the target molecule. Due to its high adsorption properties and easiness of preparation, MMIP-DMSO was used successfully as adsorbent material in solid-phase extraction coupled to a colorimetric method for sulfamethoxazole (SMX). After optimizing analytical conditions, a calibration plot was performed in the concentration range from 0.2 to 5 µg·mL-1 with limits of detection and quantitation of 0.06 and 0.2 µg·mL-1, respectively. The developed procedure was applied successfully for SMX determination in spiked tap and mineral waters showing satisfactory recoveries. Besides, reusability study demonstrated that MMIP could be reused at least 8 times keeping good binding capacity.

Finding the Sweet Spot in ERLIC Mobile Phase for Simultaneous Enrichment of N-Glyco and Phosphopeptides.

Simultaneous enrichment of glyco- and phosphopeptides will benefit the studies of biological processes regulated by these posttranslational modifications (PTMs). It will also reveal potential crosstalk between these two ubiquitous PTMs. Unlike custom-designed multifunctional solid phase extraction (SPE) materials, operating strong anion exchange (SAX) resin in electrostatic repulsion-hydrophilic interaction chromatography (ERLIC) mode provides a readily available strategy to analytical labs for enrichment of these PTMs for subsequent mass spectrometry (MS)-based characterization. However, the choice of mobile phase has largely relied on empirical rules from hydrophilic interaction chromatography (HILIC) or ion-exchange chromatography (IEX) without further optimization and adjustments. In this study, ten mobile phase compositions of ERLIC were systematically compared; the impact of multiple factors including organic phase proportion, ion pairing reagent, pH, and salt on the retention of glycosylated and phosphorylated peptides was evaluated. This study demonstrated good enrichment of glyco- and phosphopeptides from the nonmodified peptides in a complex tryptic digest. Moreover, the enriched glyco- and phosphopeptides elute in different fractions by orthogonal retention mechanisms of hydrophilic interaction and electrostatic interaction in ERLIC, maximizing the LC-MS identification of each PTM. The optimized mobile phase can be adapted to the ERLIC HPLC system, where the high resolution in separating multiple PTMs will benefit large-scale MS-based PTM profiling and in-depth characterization.

Application of high-surface-area graphitized carbon black with primary secondary amine as an alternative quick, easy, cheap, effective, rugged, and safe cleanup material for pesticide multi-residue analysis in spinach.

A multi-residue method has been developed and validated to determine 46 pesticides in spinach using liquid chromatography tandem mass spectrometry. The method is based on modified quick, easy, cheap, effective, rugged, and safe sample preparation, where high-surface-area graphitized carbon black was used first as sorbent material in the dispersive solid-phase extraction. The method was compared with the quick, easy, cheap, effective, rugged, and safe method. The morphology, surface area, pore size, and pore volume of the sorbent was determined. The results obtained show that the sorbent consists of high surface area (233m2 /g) and large pore volume (1.5cm3 /g). The calibration curve correlation coefficient (R2 ) of the method was at least 0.99. The average recoveries ranged from 74 to 116%, and limits of detection and quantification from 0.0001 to 0.002mg/kg and from 0.0002 to 0.005mg/kg, respectively. Using the method, the pesticides exhibited low matrix effect (<20%), except for nicosulfuron (29.86%), methomyl (26.77%), and flufenoxuron (24.65%). The method showed better potential to remove pigments than the quick, easy, cheap, effective, rugged, and safe method. It is demonstrated that the proposed method could be useful alternative for sample preparation of spinach and other matrices in future.

Trace analysis of quercetin in tea samples by HPLC-DAD system by means of a new nanocomposite including magnetic core-shell

ABSTRACT A new magnetic core-shell multiwalled carbon nanotube@nanodiamond nanocomposite was synthesized, characterized and used as magnetic solid-phase extraction material. The usability of material was checked on the separation and pre-concentration of quercetin in tea samples by magnetic solid-phase extraction and high-performance liquid chromatography with diode array detector system. There was a linear relationship between chromatographic area and concentration of quercetin in the range of 5.0–600 ng mL−1. The limit of detection and quantification limits were 1.46 and 4.91 ng mL−1, respectively. The developed method has been applied to determine quercetin at trace levels in tea samples.

Highly selective enrichment of phosphopeptides using poly(dibenzo-18-crown-6) as a solid-phase extraction material.

A poly(dibenzo-18-crown-6) was used as a new solid-phase extraction material for the selective enrichment of phosphopeptides. Isolation of phosphopeptides was achieved based on specific ionic interactions between poly(dibenzo-18-crown-6) and the phosphate group of phosphopeptides. Thus, a method was developed and optimized, including loading, washing and elution steps, for the selective enrichment of phosphopeptides. To assess this potential, tryptic digest of three proteins (α- casein, β-casein and ovalbumin) was applied on poly(dibenzo-18-crown-6). The nonspecific products were removed by centrifugation and washing. The spectrometric analysis was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Highly selective enrichment of both mono- and multiphosphorylated peptides was achieved using poly(dibenzo-18-crown-6) as solid-phase extraction material with minimum interference from nonspecific compounds. Furthermore, evaluation of the efficiency of the poly(dibenzo-18-crown-6) was performed by applying the digest of egg white. Finally, quantum mechanical calculations were performed to calculate the binding energies to predict the affinity between poly(dibenzo-18-crown-6) and various ligands. The newly identified solid-phase extraction material was found to be a highly efficient tool for phosphopeptide recovery from tryptic digest of proteins.

A Novel Metal-Organic Framework Composite, MIL-101(Cr)@MIP, as an Efficient Sorbent in Solid-Phase Extraction Coupling with HPLC for Tribenuron-Methyl Determination.

A highly efficient and selective method based on core–shell molecularly imprinted polymers (MIL@MIP) and high performance liquid chromatography (HPLC) was developed and firstly used for the trace analysis of tribenuron-methyl (TBM) in complicated matrices. The MIL@MIP was prepared by surface molecular-imprinting technique, specially using MIL-101 as core, TBM as template molecule, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and azobisisobutyronitrile (AIBN) as initiator. The resulting MIL@MIP showed high affinity, recognition specificity, fast mass transfer rate, and efficient adsorption performance towards TBM with the adsorption capacity reaching up to 3.217 mg/g. It also showed high cross-selectivity for TBM among its six kinds of chemical structure analogues. Furthermore, using the MIL@MIP as solid-phase extraction (SPE) materials, the recoveries of TBM determined by HPLC were 84.6-92.3%, 93.3-106.7%, and 88.9-93.3% in the spiked river water, soil, and soybean samples, respectively, with the limit of detection of 0.3 ng/L, 1.5 ng/kg, and 1.5 ng/kg, accordingly. It was proved that the developed HPLC-MISPE method was fast, accurate, and sensitive for detecting the trace TBM in river water, soil, and soybean samples.

The graphene oxide/magnesium–aluminium bimetallic hydroxides composite used as solid-phase extractant for determination of monoaromatic hydrocarbons in wastewater

ABSTRACT The graphene oxide (GO) and the magnesium–aluminium bimetallic hydroxides composite (GO/Mg-Al-LDH) was used as a solid-phase extractant for determination of toluene, ethylbenzene, p-xylene, m-xylene, o-xylene, 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene in wastewater by gas chromatography-mass spectrometry analytical method. When the amount of solid-phase extractant was 1.5 g, the extraction time was 6 min, and the elution with 2 mL of chloroform for 3 min, seven monoaromatic hydrocarbons (MAHCs) in 500 mL of water sample can be well extracted and separated. Under the optimised experimental conditions, the mass concentration of each component in the range of 0.01–5 ng/mL has a good linear relationship with the peak area, the coefficients of determination are all greater than 0.995. The relative standard deviation (n = 5) and the method detection limit range are 2.9–7.1% and 0.0005–0.005 ng/mL, respectively. The seven of MAHCs in Dongfengqu River and laboratory wastewater of Chengdu University of Technology can be effectively detected, the recovery rate and the relative standard deviation (n = 5) are 83.0–110.0% and 3.7–9.4%, respectively. For the first time, the GO/Mg-Al-LDH composite was used as a solid-phase extraction material, and seven MAHCs in water were successfully determined by GC-MS. The detection method is established with low detection limit and high reproducibility which can meet the measurement requirements of trace MAHCs in wastewater.

Synthesis and characterization of polyamide-graphene oxide-polypyrrole electrospun nanofibers for spin-column micro solid phase extraction of parabens in milk samples

In the present study, an electrospun composite of polyamide-graphene oxide-polypyrrole was synthesized. The characterization of the synthesized material was accomplished using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FT-IR). FESEM images showed uniform and beadles nanofibers. The composite was employed as a novel sorbent for spin-column micro solid phase extraction to determine parabens in milk samples. Addition of graphene oxide and polypyrrole into the polymeric network of polyamide significantly improves the extraction efficiency of the electrospun sorbent due to providing the possibility of various interactions with the target analytes such as hydrogen bonding, hydrophobic and π–π stacking. All effective parameters on the efficiency of both adsorption and desorption steps were optimized. These parameters were pH of sample solution (5.0), sorbent amount (20 mg), type and volume of desorption solvent (200 μL of methanol), number of cycles (7 and 14) and centrifugation speed (600 and 500 rpm) of both adsorption and desorption steps. Under the optimal conditions, the calibration plots were linear within the range of 10–1000, 15–1000, and 20–1000 ng mL−1 for methyl paraben, ethyl paraben and propyl paraben, respectively. Limits of detection were obtained lower than 7.0 ng mL−1 by HPLC-UV. Intra- and inter-assay relative standard deviations were less than 8.6% and 5.8%, respectively. Finally, the method was successfully applied for determination of parabens in some milk samples and good recoveries were obtained within the range of 81.7–97.8%. The results demonstrated good efficiency of the synthesized electrospun composite nanofibers as the packing material for spin-column micro solid phase extraction.

Exploring Matrix Effects on Binding Properties and Characterization of Cotinine Molecularly Imprinted Polymer on Paper-Based Scaffold

Commercially available sorbent materials for solid-phase extraction are widely used in analytical laboratories. However, non-selective binding is a major obstacle for sample analysis. To overcome this problem, molecularly imprinted polymers (MIPs) were used as selective adsorbent materials prior to determining target analysts. In this study, the use of non-covalent molecularly imprinted polymers (MIPs) for cotinine adsorption on a paper-based scaffold was studied. Fiberglass paper was used as a paper scaffold for cotinine-selective MIP adsorption with the use of 0.5% agarose gel. The effects of salt, pH, sample matrix, and solvent on the cotinine adsorption and extraction process were investigated. Under optimal conditions, the adsorption isotherm of synthesized MIPs increased to 125.41 µg/g, whereas the maximum adsorption isotherm of non-imprinted polymers (NIPs) was stable at 42.86 µg/g. The ability of the MIP paper scaffold to absorb cotinine in water medium was approximately 1.8–2.8-fold higher than that of the NIP scaffold. From Scatchard analysis, two dissociation constants of MIPs were calculated to be 2.56 and 27.03 µM. Nicotine, myosmine, and N-nitrosonornicotine were used for selectivity testing, and the calculated selectivity factor of cotinine to nicotine, myosmine, and N-nitrosonornicotine was 1.56, 2.69, and 2.05, respectively. Overall, the MIP paper scaffold is promising for simple onsite sampling of cotinine and can be used to assess tobacco smoke exposure.

Magnetic Graphene Solid-Phase Extraction for the Determination of 47 Kinds of Non-steroidal Anti-inflammatory Drug Residues in Animal Food with Liquid Chromatography Tandem Mass Spectrometry

Based on magnetic graphene (Fe3O4-G), a liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method coupled with magnetic solid-phase extraction was developed for the simultaneous detection of 47 kinds of nonsteroidal anti-inflammatory drug (NSAID) residues in meat of swine, chicken, and bovine. The samples were extracted with acetonitrile-phosphate, then the extracts were purified by dispersed solid-phase extraction based on magnetic graphene (Fe3O4-G). The linearity range is 0.1–50 μg L−1. Limits of detection were between 0.1 μg kg−1 and 0.5 μg kg−1, and limits of quantification were between 0.5 μg kg−1 and 1.0 μg kg−1. The average recoveries were 72.4–97.1% at spiking levels. The inter-day RSDs varied from 5.3 to 12.6%. Due to the advantages of easy collection of magnetic solid-phase extraction materials, the method was more rapid and efficient for the enrichment and separation without filling columns. The sensitivity, precision, and accuracy method was suitable for simultaneous detection of multi-component residues of nonsteroidal anti-inflammatory drugs.

Silica Monolith Nested in Sponge (SiMNS): A Composite Monolith as a New Solid Phase Extraction Material for Environmental Analysis.

We report a new material of a composite silica monolith nested in sponge (SiMNS) and demonstrate an application in the trace analysis of environmental contaminants in water. SiMNS is prepared through sponge absorption of a hydrolyzed mixture of siloxanes and in situ gel formation within the pores. Images obtained using scanning electron microscopy show that the silica and sponge skeletons are mutually nested in SiMNS. This nested composite structure of SiMNS enhances the mechanical flexibility of the material, allowing for reproducible production of desirable sizes and shapes for solid phase extraction (SPE) cartridges without the need to use frits. Functionalization of SiMNS provides appropriate SPE options for selective and efficient extraction of specific contaminants. SPE cartridges packed with functionalized SiMNS-SO3Na have high extraction capacity, good stability in the pH range of 2 to 11, and efficient enrichment of dipeptides in water. Extraction of six dipeptides from water using these new SiMNS-SO3Na SPE cartridges followed by HPLC-MS/MS analysis results in improved method detection limits (MDLs) of 0.02-1.3 ng/L and method quantification limits (MQLs) of 0.05-4.3 ng/L. Successful identification and quantification of three dipeptides, Tyr-Gly, Phe-Gly, and Tyr-Ala, from raw water demonstrates a useful application of the new SPE materials for environmental analysis of trace contaminants. On the basis of this work, a range of functionalized SiMNS materials can be produced and tailored for various environmental and exposomic analyses.

Bi-functionalized mesostructured silicas as reversed-phase/strong anion-exchange sorbents. Application to extraction of polyphenols prior to their quantitation by UHPLC with ion-trap mass spectrometry detection.

Hybrid mesostructured silicas with wormhole-like pore structure were synthesized and bi-functionalized with n-octyl (C8) and quaternary ammonium (NR4+) groups to obtain new sorbent materials for dispersive solid-phase extraction (dSPE) of polyphenols. Due to their nature of being both a reversed-phase and a strong anion-exchanger, the materials display mixed-mode retention mechanism. During the synthesis, the functionalization conditions were varied to obtain materials with different functionalization degree. The resulting materials (denoted as HMS-RPC8-SAX-1, HMS-RPC8-SAX-2 and HMS-RPC8-SAX-3) show high surface area, wormhole-like framework and controlled pore size. They were evaluated for multicomponent extraction of 22 polyphenols, including phenolic acids, flavonoids and stilbenes, from spiked juice samples. The sample extracts were analyzed by ultra-high performance liquid chromatography coupled to ion-trap tandem mass spectrometry. The adsorption capability, the amount of sorbent, the eluent and the elution volume were optimized. Best performance was achieved by using HMS-RPC8-SAX-2, which is the material with the highest fraction of NR4+ groups. This material has a large extraction capability and provides high recovery values of the target analytes (70-101%) as a result of its hydrophobic and anion-exchange interactions. The detection limits for polyphenols in juice range from 1 to 560ngmL-1. Graphical abstract Schematic presentation of dispersive solid-phase extraction of polyphenols from juice samples using a novel sorbent based on the bi-functionalization of mesostructured silica with n-octyl and quaternary ammonium groups, followed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis. Due to the sorbent nature of being both a reversed-phase and strong anion-exchanger, the material displays mixed mode retention mechanism that improves its extraction capability.