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Owning to the hydrophobic characteristics of microporous organic networks (MONs), their utilizations still largely limited in non- and weak-polar analytes. To expend their applications, here we reported the synthesis of a novel hollowed H-MON-PEI 1800 -2 composite via sacrifice template method and subsequent modification with polyethyleneimine (PEI) for efficient solid phase extraction of polar and ionic phenolic acid (PAs) from fruit juice samples. H-MON-PEI 1800 -2 exhibits large surface area, rapid extraction kinetics, remarkable chemical and thermal stabilities, and provides synergistic electrostatic, π-π, hydrogen bonding, and hydrophobic interaction sites for PAs. The developed method owns low limit of detection, wide linear range, large enrichment factors, and good reusability. The recoveries of H-MON-PEI 1800 -2 for PAs are 1-3 orders of magnitude higher than those of commercial adsorbents like activated carbon, C18 and Oasis HLB. This work highlights the prospects of functional H-MONs for enriching polar and ionic targets from complex sample matrices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A novel fluorinated triazine-based covalent organic frameworks (F-CTFs) was designed and synthesized by using melamine and 2,3,5,6-tetrafluoroterephthalaldehydeas as organic ligands for selective pipette tip solid-phase extraction (PT-SPE) of amphiphilic fluoroquinolones (FQs). The competitive adsorption experiment and mechanism study were carried out and verified that this F-CTFs possesses favorable adsorption affinity for FQs. The abundant fluorine affinity sites endowed the F-CTFs high selectivity to FQs extraction through F-F interactions. The adsorption capacity of F-CTFs can reach up to 109.1 mg g -1 for enrofloxacin. The detailed characterization of the F-CTFs adsorbent involved the application of various techniques to examine its morphology and structure. Under optimized conditions, a method combining F-CTF-based PT-SPE with high-performance liquid chromatography (PT-SPE-HPLC) was established, which exhibited a broad linear range, excellent precision, and an impressively low limit of detection, and could be used for the determination of six FQs in milk, with LODs as low as 0.0010 μg mL -1 . The recovery rates during extraction varied between 92.1% and 111.4%, exhibiting RSDs below 6.8% at different spiked concentrations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, we propose a novel strategy utilizing deep eutectic solvents (DESs) as both the extraction solvent and dispersing liquid, with nanometer zinc oxide (ZnO) serving as the adsorbent. This method incorporates ultrasound-assisted matrix solid phase dispersion (UA-MSPD) for the extraction of six active components (salidroside, echinacoside, acteoside, specnuezhenide, nuezhenoside G13, and oleanolic acid) from Ligustri Lucidi Fructus samples. The extracts were then analyzed using high-performance liquid chromatography equipped with a diode array detector. The effects of various parameters such as dispersant dosage, DESs volume, grinding time, ultrasonication duration, and eluent volume on extraction recovery were investigated and optimized using a central composite design under response surface methodology. The optimized conditions yielded detection limits ranging from 0.003 to 0.01 mg/g and relative standard deviations of 8.7% or lower. Extraction recoveries varied between 93% and 98%. The method demonstrated excellent linearity for the analytes (R 2 ≥ 0.9997). The simple, green, and efficient DESs/ZnO-UA-MSPD technique proved to be rapid, accurate, and reliable for extracting and analyzing the six active ingredients in Ligustri Lucidi Fructus samples., (© 2024 Wiley‐VCH GmbH.)

Simultaneous monitoring of plasma concentration levels of multiple antiepileptic drugs (AEDs) is essential for dose adjustment in comprehensive epilepsy treatment, necessitating a sensitive technique for accurate extraction and determination of AEDs. Herein, a magnetic solid-phase extraction (MSPE) technique on the basis of modified biochar (BC) is investigated to extract four AEDs from plasma, in conjunction with high performance liquid chromatography. BC derived from Zizyphus jujuba seed shells was activated by phosphoric acid (PBC) and magnetized via coprecipitation to produce MPBC. The MPBCCD obtained after modification with β-cyclodextrin (CD) was characterized and evaluated for adsorption. It exhibited fast adsorption kinetics based on second-order kinetics and satisfactory adsorption capacity for AEDs. Then it was employed as the MSPE adsorbent and the influencing parameters were optimized. The enrichment factor was 18.75. The validation analysis revealed a favorable linearity that ranged from 0.04 to 20 μg·mL -1 along with a low limit of detection of 6.85 to 10.19 ng·mL -1 . The recovery of the AEDs ranged from 78.7 to 109.2 %, with relative standard deviations below 6.7 %. Using quantum chemistry theory calculations and experimental results analysis, the adsorption mechanism was investigated. It disclosed that the suggested strategy built upon MPBCCD was appropriate for the assessment of AEDs in plasma and expanded the usage of BC as the environmentally favorable matrix for the analysis of biological samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

A zwitterionic magnetic microporous organic network (MMON-SO 3 H-NH 2 ) with numerous amino and sulfonic acid ion-pare binding sites was designed and synthesized for efficient magnetic solid-phase extraction (MSPE) of fluoroquinolones (FQs) from meat samples. The core-shell MMON-SO 3 H-NH 2 offered large specific surface area, rapid magnetic responsiveness, good stability, and multiple binding sites for FQs. The density functional theory and independent gradient model evaluations confirmed hydrogen bonding, π-π and ion-pair interactions between MMON-SO 3 H-NH 2 and FQs. Under the optimal conditions, the established MMON-SO 3 H-NH 2 -MSPE-HPLC-UV method gave wide linear range (0.15-1000 μg L -1 ), low limits of detection (0.05-4.5 μg L -1 ) and limits of quantitation (0.15-13 μg L -1 ), and high enrichment factors (82.1-99.6) using 3 mg of adsorbent. This work demonstrates that the preparation of zwitterionic MONs is an efficient way to promote the extraction performance of MONs for zwitterionic targets and provides an effective sample pretreatment method for enriching and monitoring FQs in complex food matrices., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this work, a core-shell structured magnetic covalent organic framework named as M-TpDAB was constructed with 3,3'-diaminobenzidine (DAB) and 1,3,5-triformylphloroglucinol (Tp) as building units. M-TpDAB was characterized by infrared spectroscopy, nitrogen adsorption-desorption isotherms, powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Using the M-TpDAB as adsorbent, a simple and highly effective method was proposed for preconcentrating phenylurea herbicides before high performance liquid-phase chromatography analysis. In the optimized conditions, a good linearity was achieved within the range of 0.15-100 ng mL -1 for water sample, 1.0-100.0 ng mL -1 for tea drink samples. The limits of detection for the analytes were 0.05-0.15 ng mL -1 for water sample and 0.30-0.50 ng mL -1 for drink samples. Satisfactory recoveries of spiked target compounds were in the range of 84.6%-105% for water sample and 80.3%-102% for tea drink samples. Finally, the M-TpDAB based method was successfully used to determine phenylurea herbicides in tea drinks and water samples, demonstrating a good alternative for analyzing trace level of phenylurea herbicides in water samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)

A simple, green, and efficient mechanochemical approach was developed herein to prepare tunable magnetic graphene oxide nanoparticles. The obtained nanoparticles were successfully used as adsorbents in a magnetic dispersive solid-phase extraction method to extract three cationic dyes (i.e., thioflavine T, auramine-O, and basic orange 2) found in food samples. Our proposed approach also utilized high-performance liquid chromatography with ultraviolet detection. Several key variables affecting the extraction recovery were investigated. These included the sample pH, amount of extractant, extraction time, sample volume, elution solvent type and volume, and the stability and reusability of the magnetic graphene oxide nanoparticles. Under optimized conditions, the calibration curve was linear at a concentration range of 0.005-1.0 μg/mL with a correlation coefficient of 0.9992-0.9996. Moreover, the limits of detection were determined at 0.97-1.35 μg/mL. The extraction mechanism was investigated via ultraviolet-visible spectrophotometry and zeta-potential analyses. The developed method was used to analyze the above-mentioned cationic dyes in bean products and yellow fish samples. Notably, satisfactory spiked recoveries ranging from 90.7 to 104.9% were achieved., (© 2021 Wiley-VCH GmbH.)

We prepared two-dimensional (2D) bimetallic metal-organic frameworks (Ni-ZIF-8) nanosheets by a simple solvent-free method at room temperature. The morphology and composition of Ni-ZIF-8 can be controlled through adding different amounts of Ni. And then, the 2D magnetic mesoporous nanosheets (Ni/ZnO@C) were synthesized by directly pyrolyzing Ni-ZIF-8 under argon atmosphere and explored as magnetic solid phase extraction (MSPE) adsorbents for the determination of nitroimidazole antibiotics (NIABs). Magnetic Ni nanoparticles embedded in carbon nanosheets uniformly resulted in high magnetization saturation of Ni/ZnO@C for easy separation. The Ni/ZnO@C can form hydrogen bond and π-π interaction with three NIABs resulting from their rich N-H containing imidazole, π-electron. Due to the high specific surface area and high mass transfer rate of 2D Ni/ZnO@C, the materials showed satisfactory adsorption capacity and rapid adsorption kinetics for NIABs. A rapid and effective method of Ni/ZnO@C-MSPE combined with high-performance liquid chromatography was proposed for the determination of NIABs. Several main parameters affecting MSPE were investigated. Under the optimal conditions, wide linear was achieved ranging from 0.1 to 500 µg⋅L -1 with a low detection limit of 0.025-0.05 µg⋅L -1 . The established method has been successfully applied to analyze NIABs from environmental water samples with satisfactory recovery from 74.33 to 105.71%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)

In this study, a new floating dispersive solid phase extraction method based on deep eutectic solvents has been developed in a home-made extraction device for the extraction of four tetracycline antibiotics from milk samples. In this approach, the sorbent (activated carbon) was dispersed in whole parts of solution with the aid of air stream and floated on top of the solution with the aid of the surfactant (lauryl betaine) and air bubbles. After collection of the sorbent, the adsorbed analytes were eluted with tetrabutyl ammonium chloride-propionic acid deep eutectic solvent under sonication. In this method, there was no need of organic dispersive and extraction solvents and the used sorbent was collected on top of the solution and collected without centrifugation. The validation parameters showed that low limits of detection (0.1-0.3 μg/kg) and quantification (0.6-1.0 μg/kg), acceptable enrichment factors (52-60), efficient extraction recoveries (80-91%), and satisfactory relative standard deviations (≤9.8%) were obtained. Eventually, the method was successfully applied on different milk samples and tetracycline was determined in them., (© 2021 Wiley-VCH GmbH.)

In the current study, a novel covalent organic frameworks COF-SCU1 incorporated electrospun nanofibers (PAN@COF-SCU1 nanofibers) was fabricated via a facile electrospinning method and utilized as adsorbent in pipette tip solid-phase extraction (PT-SPE) of tetracycline antibiotics (TCs) from foods. The prepared PAN@COF-SCU1 nanofibers possessed both of the unique characteristics of electrospun nanofibers and COFS-CU1, and thus improving the adsorption capacity of the electrospun nanofibers and preventing the problems of leakage and high pressure caused by directly using the nanosize COFs as adsorbent in PT-SPE. The experiments affected the adsorption and desorption efficiencies, such as the loading ratios of COFS-CU1 in nanofibers, the amount of nanofibers, the matrix pH and desorption solvent, were studied in detail. Eventually, a new pipette tip solid-phase extraction-high performance liquid chromatography (PT-SPE/HPLC) method was proposed for the analysis of three TCs from food. Satisfied linearity for TCs was obtained in the range of 4-70 ng mL -1 . The limits of detection and quantification were ranged from 0.6 to 3 ng mL -1 and from 2 to 10 ng mL -1 , respectively. The interday and intraday precisions (RSD) were all lower than 9%. The proposed PT-SPE/HPLC method was used to determine TCs residues in grass carp and duck samples for the first time. The results could not only explore the availability of PT-SPE in the extraction of TCs in food samples, but also broadened the potential applications of COFs in sample preparation., Competing Interests: Declaration of Competing Interest We wish to draw the attention of the editor to the following facts which may be considered as potential conflicts of interest and to significant financial contributions to this work., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Herein, we developed a novel magnetic solid phase extraction method based on attapulgite-modified magnetic metal-organic frameworks (ATP@Fe 3 O 4 @ZIF-8), and this method could be used for the determination of benzoylureas when it was coupled with high-performance liquid chromatography. The established method was validated in terms of linearity (2.5-500 μg L -1 , with correlation coefficient (R 2 ) > 0.9994), accuracy (with satisfactory recovery of 88.29-95.99%) and precision (with relative standard deviation (RSD) of less than 8%). In addition, the enrichment factors (EF) ranged from 63.6 to 72.2. Limit of detection (LOD) and limit of quantitation (LOQ) were 0.7-3.2 μg L -1 and 2.3-10.7 μg L -1 , respectively. Moreover, there was hardly any noticeable loss of the extraction efficiency when this extraction method undergoes five cycles. Finally, this method was successfully used for the determination of six benzoylureas in different tea infusions and the determined relative recoveries ranged from 78.8 to 114.3%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this work, the molecularly imprinted polymer nanoparticles (MIP-NPs) for the selective determination of fluvoxamine have been described. The polymer nanoparticles were synthesized by the polymerization of methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, 2,2-azobisisobutyronitrile as an initiator and fluvoxamine as a template molecule. The MIP-NPs were characterized using techniques that included Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Imprinted fluvoxamine molecules were removed from the polymeric structure using acetonitrile in methanol (2:8; v/v) as the eluting solvent. The linear dynamic range for fluvoxamine was 10-1200 μg L-1. The developed method was successfully applied to the extraction of fluvoxamine in complex biological samples., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Microporous organic network (MON) is a promise class of functional materials in solid phase extraction (SPE). However, the previous MON-based SPE works are all focused on off-line mode. The inherent drawbacks of off-line SPE such as complicated operation steps and poor repeatability still hinder the potential applications of MON. In addition, direct use of traditional synthesized nano-sized MON in on-line SPE is impractical. To solve these issues, here we show the synthesis of silica amino-functionalized MON (SiO 2 @MON-NH 2 ) microsphere as an advanced adsorbent for on-line SPE of trace phenols prior to the high performance liquid chromatography (HPLC) analysis. The SiO 2 microsphere is served as the core to support the in-situ engineering of MON-NH 2 to reduce the back pressure during on-line SPE. Integrating amino groups (hydrogen binding sites) with aromatic MON's networks (hydrophobic and π-π interaction sites) on SiO 2 @MON-NH 2 provides supersensitive performance for phenols. The SiO 2 @MON-NH 2 microsphere for on-line SPE coupled with HPLC for the analysis of five phenols offers low limit of detections (S/N = 3, 0.009-0.030 μg L -1 ), wide linear range (0.025-100 μg L -1 ), large enrichment factors (5036-5689) and good intra-day and inter-day precisions (RSDs, 0.7-1.6 and 1.0-2.7%, respectively). The proposed method is also successfully applied to analyze trace phenols in tap, lake and river water samples with good recoveries. The newly-synthesized MON composites own great potential in on-line SPE for further determination of diverse trace contaminants., Competing Interests: Declaration of Competing Interest There are no conflicts to declare., (Copyright © 2019. Published by Elsevier B.V.)

In this work, core/shell magnetic molecularly imprinted polymer nanoparticles were synthesized for extraction and pre-concentration of valsartan from different samples and then it was measured with high-performance liquid chromatography. For preparation of molecularly imprinted polymer nanoparticles, Fe 3 O 4 nanoparticles were coated with tetraethyl orthosilicate and then functionalized with 3-(trimethoxysilyl) propyl methacrylate. In the next step, molecularly imprinted polymer nanoparticles were synthesized under reflux and distillation conditions via polymerization of methacrylic acid, valsartan (as a template), azobisisobutyronitrile and ethylene glycol dimethacrylate as cross linking. The properties of molecularly imprinted polymer nanoparticle were investigated by FTIR spectroscopy, field emission scanning electron microscopy, and X-ray diffraction. Box-Behnken design with the aid of desirability function was used for optimizing the effect of variables such as the amounts of molecularly imprinted polymer nanoparticles, time of sonication, pH, and volume of methanol on the extraction percentage of valsartan. According to the obtained results, the affecting variables extraction condition were set as 10 mg of adsorbent, 16 min for sonication, pH = 5.5 and 0.6 mL methanol. The obtained linear response (r 2  > 0.995) was in the range of 0.005-10 µg/mL with detection limit 0.0012 µg/mLand extraction recovery was in the range of 92-95% with standard deviation less than 6% (n = 3)., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Magnetic carbon nanotubes (CNTs) with encapsulated Co nanoparticles (Co@CNTs), was synthesized by exploiting the one-step pyrolysis strategy using ZIF-67 as template. The as-synthesized Co@CNTs is provided with the nanopores, a large specific surface area, and strong magnetic response. The obtained Co@CNTs was used as magnetic solid-phase extraction adsorbents to extract two profens including flurbiprofen and ketoprofen. The parameters of extraction efficiency, involving extraction time, sample solution volume, ionic strength, pH and the conditions of desorption efficiency, were optimized in detail. After determined by high-performance liquid chromatography-ultraviolet (HPLC-UV), the results evinced that Co@CNTs showed a high extraction efficiency with high enrichment factors of 832 and 672. The good linear range of both flurbiprofen and ketoprofen were all 5.0-1000 ng L -1 , with the limit of detection were 0.60 ng L -1 and 0.70 ng L -1 , respectively. Furthermore, a valid method for the extraction of flurbiprofen and ketoprofen from human serum was established. The spiking recoveries of two profens were between 86.74% and 97.22%, and the relative standard deviation was less than 6.55%. Co@CNTs can be repeatedly used at least 10 times, indicating its excellent regeneration and reusability. The results demonstrated that the Co@CNTs materials exhibits high enrichment ability and extraction efficiency, playing great promise in MSPE., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Bisphenol A (BPA), a known potential endocrine disrupting compound (EDC) is expected to be present in low quantities in canned food due to its migration from the inner surface coating of cans made of epoxy resins. A selective and confirmatory analytical method, based on microwave assisted extraction (MAE), molecularly imprinted solid phase extraction (MISPE) using a polymer prepared by a non-covalent molecular imprinting technique and liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI/MS) was developed for the determination of BPA in canned pineapple, tuna and mushrooms. First, the effect of the loading medium of hydro- organic solutions on the binding of BPA and its deuterated analogue on the MISPE sorbent was investigated. Subsequently, the effects of the experimental conditions of the microwave assisted extraction (solvent, sample mass/solvent volume, time and temperature) on the obtained recovery of BPA from canned food were assessed and the parameters were optimized to provide maximum recovery and selectivity. It was demonstrated that the combination of MAE with MISPE permits the use of a selective extraction solvent (methanol/water, 4/6, v/v), simplifying the sample preparation steps and enhancing sample clean-up of complex food matrices. The method was validated in different food matrices, using BPA-d16 as internal standard and quantitative relative recoveries were determined. The precision (RSD %) of the method ranged from 7% to 10% and the limit of detection was at low ng/g level for all food matrices. The determined concentration of BPA in commercial canned samples ranged between 7.3 and 42.3 ng/g., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A simple and efficient sample preparation method to extract four bioactive compounds (echinacoside, specnuezhenide, oleuropein and nuezhenoside G13) from Ligustri Lucidi Fructus was established by vortex-forced matrix solid phase dispersion (VFMSPD) method. Chitosan solution was applied as green eluent in this procedure and Celite AZO was employed as dispersant. High performance liquid chromatography (HPLC) equipped with ultraviolet (UV) detector was used to analyze the target analytes. The best result of the investigation was obtained with Celite AZO as dispersant, sample/ dispersant ratio as 1:1, grinding for 2 min, 1 mL high-viscosity chitosan solution (0.5 mg mL -1 ) used as the elution reagent and vortex mixing for 1.5 min. The method exhibit a good linearity for the analytes (r 2  > 0.999). The absolute recoveries of the four target compounds in Ligustri Lucidi Fructus ranged from 90.7% to 98.8% and the relative recoveries of the target compounds ranged from 99.2% to 102% (RSD ≤ 3.4%), which were obtained by the final optimization method. Consequently, the newly developed chitosan solution-based vortex-forced matrix solid phase dispersion (MSPD) combined with HPLC could be efficiently applied to extract and analyze the target compounds in Ligustri Lucidi Fructus samples., (Copyright © 2019. Published by Elsevier B.V.)

In this paper, a novel core-shell structure magnetic microsphere Fe 3 O 4 @SiO 2 -TPM@StVp(Fe 3 O 4 @SiO 2 -3-(trimethoxysilyl)propyl methacrylate@styrene and n-vinylpyrrolidone) was successfully synthesized and used as a magnetic solid-phase extraction adsorbent for extraction of aristolochic acid I (AAI) in traditional Chinese medicine soup. The prepared Fe 3 O 4 @SiO 2 -TPM@StVp was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and Fourier-transform infrared spectroscopy (FT-IR). The microspheres have various advantages of excellent hydrophilicity and π-electron system, which is very suitable for determining target analytes followed by high performance liquid chromatography (HPLC). The main factors, including the pH of samples, amount of adsorbent, adsorption time, elution solvent and desorption time, were optimized. Under optimal conditions, the proposed method showed a wide linear range of 0.4-10 µg/mL and a good correlation coefficient (R 2  = 0.9918). The pretreatment procedure was achieved within 10 min. The recoveries of aristolochic acid I in real samples range from 80.9% to 89.6% with relative standard deviations less than 4.9%, highlighting the accuracy of this method., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Metal-organic coordination polymer beads (MOCBs) are described for use as a sorbent for solid-phase extraction of chlorophenoxy herbides. By applying regulation of Co(II) ions, micro-sized monodisperse MOCBs were obtained through the microwave heating. The MOCBs-based method displays excellent extraction efficiency towards chlorophenoxy herbicides, specifically of 2-chlorophenoxyacetic acid, 4-chlorophenoxyacetic acid, 4-chloromethylphenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid and 2-(2,4-dichlorophenoxy)propionic acid. Following extraction, the herbicides were eluted with 8% formic acid in methanol and quantified by HPLC. The method, when applied to analyze spiked cereals, exhibits a wide linear range (from 0.6 to 1000 ng g -1 ) and low limits of quantification (ranging from 0.10 to 0.25 ng g -1 ). For a single column, the inter-day and intra-day precisions, expressed as the relative standard deviation are in the range of 2.5-6.8%. The batch-to-batch reproducibility (for n = 3) is <4.6%. For spiked cereal samples, relative recoveries are very good (90.3-102.3%, for n = 4). The extraction efficiency of MOCBs remains unchanged after reusing for 40 times. Graphical abstractSchematic presentation of Co(II)-doped metal-organic coordination polymer beads (Co(II)@MOCB) using for solid-phase extraction (SPE).

A solid phase extraction (SPE) method with a porous organic polymer as adsorbent was established for the extraction of five carbamate pesticides (metolcarb, carbaryl, isoprocarb, bassa and diethofencarb) from milk, white wine and juice samples prior to high performance liquid chromatography-diode array detection. The main factors affecting the SPE were optimized, including sample volume, sample loading rate, sample solution pH, desorption conditions and cartridge reusability. Under the optimal conditions, a good linearity existed in the range from 1.0 to 320.0 ng mL -1 for milk and white wine samples and from 0.5 to 160.0 ng mL -1 for juice sample with the correlation coefficients between 0.9956 and 0.9998. The method recoveries of the carbamates were 82.0%-110.0%. The limits of detection were 0.12-0.40 ng mL -1 for milk and white wine samples, and 0.06-0.20 ng mL -1 for juice sample. The adsorption mechanism of the adsorbent was investigated by the extraction of different types of organic compounds (carbamates, benzoylurea insecticides, endocrine disrupting chemicals and polycyclic aromatic hydrocarbons) with the adsorbent. The results showed that the existence of the hydrogen-bonding between the adsorbent and the analytes is favorable for the adsorption and strong hydrophobicity seems to have an adverse effect., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Mesoporous KIT-6-magnetite composite (Fe 3 O 4 @SiO 2 @KIT-6) was successfully prepared and characterized by transmission electron microscopy, scan electron microscopy, elemental mapping, energy dispersive X-ray spectrum, Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray powder diffraction, Brunauer Emmett Teller analysis and magnetic property analysis. It was then applied as adsorbent for magnetic solid phase extraction of fenpropathrin, lambda-cyhalothrin, S-fenvalerate and bifenthrin from water samples before analyzed by high performance liquid chromatography-ultraviolet detector. A few factors impacting extraction were studied. The optimal results were acquired by using acetonitrile to eluent the targets adsorbed on 40 mg of Fe 3 O 4 @SiO 2 @KIT-6 adsorbent in 100 mL water samples at a pH of 7 at 25 ℃ within 10 min. The experimental limit of detections of fenpropathrin, cyhalothrin, S-fenvalerate and bifenthrin are 0.01 × 10 -3 , 0.006 × 10 -3 , 0.01 × 10 -3 and 0.005 × 10 -3 mg∙L -1 , respectively. Good relative recoveries (86.58-98.80%) and reproducibility values are also obtained. The kinetic experiment shows that the adsorption follows pseudo-second order, while the isotherm experiment follows Langmuir isotherm model. Trace pyrethroid pesticides in water samples can be detected by the developed magnetic solid phase extraction technique followed by high performance liquid chromatography, which is simple, easy, environmental friendly and efficient., (Copyright © 2019 Elsevier B.V. All rights reserved.)

For the first time, a magnetic solid-phase extraction with high-performance liquid chromatography detection method using Zr functionalized Fe 3 O 4 magnetic material to enrich ribavirin was successfully established. Zr components that modified in Fe 3 O 4 nanoparticles via a simple one-step hydrothermal method was selected in this work to specifically capture ribavirin by the strong chemical bonding between Zr components of Zr functionalized Fe 3 O 4 magnetic material and cis-hydroxyl of ribavirin, which was confirmed by pseudo-second-order kinetic model. And Fe 3 O 4 components were selected in this work to achieve simple operation. Under the optimal experimental conditions, proposed magnetic solid-phase extraction with high-performance liquid chromatography detection method along with Zr functionalized Fe 3 O 4 magnetic material offered a wide range linearity at 10-200 µg/L with correlation coefficient of 0.9978 with low detection limit of 2.68 µg/L for ribavirin. The relative standard deviations obtained from nine parallel extractions of 100 µg/L ribavirin were 4.41% and revealed good repeatability. This established method was successfully applied to detect real samples including chicken liver, egg, and shrimp with satisfactory recoveries of 74.13-92.9%., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The amino-modified covalent organic framework (NH 2 @COF) was synthesized via the thiol-ene click reaction of vinyl covalent organic framework (COF) with 4-aminobenzenethiol. The introduction of amino groups can interact with the anionic headgroup of carboxylic acid pesticides. Moreover, ample hydrophilic surface area can boost absorption in the water media. The NH 2 @COF was fully characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Compared with vinyl COF and four commercial absorbents, the NH 2 @COF shows higher extraction efficiency for carboxylic acid pesticides. The solid phase extraction (SPE) conditions, involving flow rate, ionic strength, sample pH, desorption solvent, and desorption solvent volume, were optimized in details. Under the optimized conditions, the NH 2 @COF was successfully applied for the enrichment and determination of six carboxylic acid pesticides in environmental water samples combined with high performance liquid chromatography. The method features wide linearity (0.2-100 ng mL -1 , r > 0.999), low limits of quantification (0.04-0.20 ng mL -1 ), and excellent precision (RSDs ≤ 8.7%). The recoveries range from 89.6% to 102.4% with RSDs ≤ 7.1%. Therefore, the NH 2 @COF-SPE method is an efficient pretreatment procedure and can be utilized for the selective extraction of carboxylic acid pesticides from environmental water samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, covalent organic frameworks SNW-1 incorporated polyacrylonitrile (SNW-1@PAN) nanofiber was synthesized and used as pipette tip solid phase extraction (PT-SPE) adsorbent for preconcentration of five sulfonamides (SAs) in meat samples. The SNW-1@PAN nanofiber was fabricated via two steps, including the hydrothermal synthesis of SNW-1 and co-electrospinning of the SNW-1/PAN mixture. The three dimensional networks of electrospun nanofiber provide both low backpressure and rapid mass transfer in PT-SPE application, thus preventing the problems of high backpressure and leakage caused by directly packing SNW-1 into PT-SPE cartridge. The SNW-1@PAN nanofiber packed PT-SPE cartridge was used to extract SAs in meat samples followed by high performance liquid chromatography (HPLC). The effects of different parameters influencing the extraction and desorption efficiency were intensively investigated and optimized. Under the optimum conditions, the linear ranges of SAs were in the range of 5-125 ng mL -1 with correlation coefficients above 0.998, and the limits of detection of the five SAs ranged from 1.7 to 2.7 ng mL -1 . The interday and intraday precision (RSD) for five replicate extractions of the five SAs (50 ng mL -1 for each) was in the range of 5.4-9.2%. The applicability of the proposed method was examined by analyzing the SAs in the pork and chicken samples. The recoveries of the five SAs varied in the range of 86-111% with good precision, showing the good capability of the proposed method for the determination of SAs in the complicated real samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Capsaicinoids were extracted from a range of spices and chillies using methanol, prior to concentrating the compounds using solid-phase extraction cartridges and water/methanol (50:50% v/v) as the solvent, followed by elution with acetonitrile. The primary extraction procedure, involving only sonication of the spices in methanol, gave results comparable to a procedure that used a combination of sonication, stirring and centrifuging. The voltammetric quantification of the capsaicinoids, at approximately +0.5 V vs. ferrocene 0/+ that were transferred from methanol/water into acetonitrile/water via solid phase extraction, was carried out in microcentrifuge tubes. Linear calibration curves for voltammetry measurements were obtained from low ppm up to at least 1400 ppm of capsaicinoids, with concentrations being detected in the different source extracts (paprika, tabasco sauce, cayenne pepper, and fresh chillies) from approximately 17 to 430 ppm, which corresponded to values of between approximately 130 and 4000 ppm, respectively, present in the original samples., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A melamine-based porous organic polymer (mPMF) was synthesized as solid phase extraction (SPE) adsorbent for inline SPE-high performance liquid chromatography (HPLC)-ultraviolet detector (UV) analysis of five phytohormones. Melamine contributed to the rich π-electron and N-containing triazine structure for mPMF, which could form π-π interaction and intermolecular hydrogen bond with COOH containing phytohormones. The synthesized mPMF adsorbent shows extremely high extraction efficiency for five target analytes (>80%) including salicylic acid, indole-3-acetic acid, abscisic acid, 2,4-dichlorophenoxyacetic acid and 1-naphthalene acetic acid. The factors affecting extraction of the target phytohormones were investigated and the optimized experimental conditions were established. The linear range was 0.2-100 μg/L with the limits of detection in the range of 0.06-0.11 μg/L for five target phytohormones. The developed method of mPMF-inline-SPE-HPLC-UV was applied for the analysis of trace target phytohormones in tomato and grape juice samples, and the recovery in the range of 83.1-116% and 87.2-121% was obtained for the spiked tomato and grape juice, respectively. This method has the advantages of high sensitivity and good reproducibility, and it has good application potential for the analysis of phytohormones in fruit samples. Moreover, inline analysis avoided the problems of sample pollution and sample loss, and provided a sample throughput of 5/h., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A composite monolithic column was prepared by redox initiation method for the on-line purification and enrichment of β-sitosterol, in which graphene oxide (GO) was embedded. The obtained monolithic column was characterized by scanning electron microscopy (SEM) and nitrogen adsorption-desorption isotherm measurement, which indicated that the monolith possessed characteristics of porous structure and high permeability. Under the optimum conditions for extraction and determination, the calibration equation was y = 47.92 × -0.1391; the linear range was 0.008-1.0 mg mL -1 ; the linear regression coefficient was 0.998; the limit of detection (LOD) is 2.4 μg mL -1 ; the limit of quantitation (LOQ) was 8 μg mL -1 ; precisions for intra-day and inter-day assays presented as relative standard deviations were less than 4.3% and 6.8%, respectively. Under the selective conditions, the enrichment factor of the method was 119. The recovery was in the range of 80.40-98.00%. Moreover, the adsorption amount of the monolith was compared with silica gel-C18 adsorbent and the monolith without graphene oxide being embedded. The polymerization monolithic column showed high selectivity and good permeability, and it was successfully used as on-line solid-phase extraction (SPE) column for determination of β-sitosterol in edible oil., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, magnetic zeolitic imazolate framework-8 (Fe 3 O 4 @ZIF-8) was successfully synthesized by a typical hydrothermal method. The facile magnetic solid-phase extraction (MSPE) based on Fe 3 O 4 @ZIF-8 was proposed for concentrating polymer additives (antioxidants and ultraviolet absorbers). The conditions of MSPE process were optimized. An analytical method of magnetic solid-phase extraction followed by high performance liquid chromatography (MSPE-HPLC) was successfully established for the simultaneous determination of seven polymer additives in drinks and foods packed with plastic. The established method showed good precision, reproducibility, stability, and accuracy with the low limits of detection (0.03-0.15 ng/mL) and limits of quantification (0.08-0.50 ng/mL). The results of this study indicated the Fe 3 O 4 @ZIF-8 coupled with HPLC provided an efficient enrichment and determination method for polymer additives in drinks and foods., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: To establish a method for determination the S - phenylmercapturic acid in urine by dispersive solid - phase extraction using Humic Acid/Fe(3)O(4) magnetic nanocomposite as adsorbent. Methods: The 5 ml of urine samples were adjusted to pH 1.0 and extracted by Fe3O4@HA. Then the analytes were separated on EC-C(18) capillary column and detected by HPLC-VWD. The S-phenylmercapturic acid was characterized by the retention time and quantified by peak area and external standard method. Results: The standard curves of SPMA showed significant linearity between 0.04~1.00 mg/L ( r =0.999 7) . The average recovery was 94.2%~102.4%. The intra-day and inter-day precisions ( RSD ) were 2.9~6.7% ( n =6) and 3.1~7.5% ( n =6) respectively. The detect limit of SPMA was 0.012 g/L (S/N=3) . Conclusion: This method is simple, rapid, sensitive and accurate. It is applicable for determination of SPMA in the urine of works who were exposed to benzene.

A covalent organic framework named TpAzo was successfully fabricated by a simple and environmentally friendly mechanochemical grinding method based on the Schiff base aldehyde-amine condensation reaction between 1,3,5-triformylphloroglucinol (Tp) and 4,4'-azodianiline (Azo), with p-toluene sulphonic acid as a molecular organizer. The TpAzo was characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The TpAzo possessed a sheet-like morphology, rich porosity and high thermal stability. The extraction performance of the TpAzo was investigated by using it as the solid phase extraction adsorbent for the extraction of benzoylurea insecticides (BUs) from juice, tomato and white radish samples prior to high performance liquid chromatographic analysis. Under the optimal conditions, a good linearity for the BUs existed in the range of 1.0-160.0 ng mL -1 for juice sample and 0.5-80.0 ng g -1 for tomato and white radish samples with the correlation coefficients of 0.9956-0.9999. The limits of detection for the analytes were 0.1-0.2 ng mL -1 for juice sample and 0.05-0.1 ng g -1 for tomato and white radish samples. The method recoveries for the analytes fell in the range of 84.1%-108.6%. The adsorption mechanism of the TpAzo was investigated by using it to extract different types of organic compounds, including phthalates, phenylurea herbicides and carbamate insecticides. The results showed that the π-stacking and hydrophobic interactions between the TpAzo and the analytes played an important role for the adsorption., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Graphene oxide wrapped silica nanocomposites were synthesized and selected as solid phase extraction adsorbents for high performance liquid chromatography analysis of aflatoxins. The major parameters affecting extraction efficiency were optimized, including the amount of adsorbents, extraction time and desorption conditions. The limit of detections and the limit of quantifications were from 0.1 to 0.3 µg/kg and from 0.3 to 1.0 µg/kg, respectively. The recoveries of aflatoxins in the spiked maize and rice samples were in the range of 76.8-104.7% and 81.1-106.9%, respectively, and with the RSDs less than 12.4%. The proposed method was proven to be simple, rapid and reliable for routine analysis of aflatoxins in crops., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this work, a magnetic β-cyclodextrin polymer was successfully prepared and used as an adsorbent for the magnetic solid-phase extraction of six benzoylurea insecticides (diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, flufenoxuron, and chlorfluazuron) from honey, tomato, and environmental water samples. The influence of the main experimental conditions on the extraction was studied. Under the optimized conditions, the β-cyclodextrin polymer@Fe 3 O 4 showed an excellent extraction performance for the benzoylurea insecticides. A good linearity was obtained for the analytes in the range of 3.0-800 ng/g for honey samples, 0.3-160 ng/g for tomato samples, and 0.1-80.0 ng/mL for water samples, with the correlation coefficients above 0.9998. Satisfactory repeatabilities were achieved, with the relative standard deviations less than 5.7%. The limits of detection (S/N = 3) of the method for the benzoylurea insecticides were 0.2-0.8 ng/g for honey samples, 0.04-0.10 ng/g for tomato samples, and 0.02-0.05 ng /mL for water samples. The method was successfully used for the determination of the six benzoylurea insecticides residues in honey, tomato, and environmental water samples with a satisfactory result., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this study, a novel method was proposed to sensitively determine aflatoxin B 1 (AFB 1 ) in peanut sample by using a carbon quantum dots-coated dummy molecularly imprinted polymer (CDs-DMIP) monolithic column for pretreatment coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD). The CDs-DMIP monolithic column was prepared by in-situ polymerization in a water bath using 5,7-dimethoxycoumarin as dummy template molecule. The CDs-DMIP monolithic column was applied to determine AFB 1 by HPLC-FLD. Satisfactory linearity was obtained over 0.5-2000ngmL -1 , with a high correlation coefficient of 0.9999. The recoveries of AFB 1 in peanut sample ranged from 79.5% to 91.2%, and the intraday and interday relative standard deviation ranged from 1.2% to 4.9%. Limit of detection (S/N=3) and limit of quantitation (S/N=10) were 0.118ngmL -1 and 0.393ngmL -1 , respectively. Under the optimized conditions, the enrichment factor was over 71-fold. AFB 1 in peanut sample and even some other samples could be sensitively determined by CDs-DMIP-HPLC-FLD method., (Copyright © 2017 Elsevier B.V. All rights reserved.)

On the basis of magnetic molecularly imprinted polymer (MMIP) solid-phase extraction coupled with high performance liquid chromatography, we established a new method for the determination of the 4-methylimidazole (4-MEI) in soy sauce. Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) were used to characterize the synthesized MMIPs. To evaluate the polymers, batch rebinding experiments were carried out. The binding strength and capacity were determined from the derived Freundlich isotherm (FI) equation. The selective recognition capability of MMIPs was investigated with a reference compound and a structurally similar compound. As a selective pre-concentration sorbents for 4-methylimidazole in soy sauce, the MMIPs showed a satisfied recoveries rate of spiked samples, ranged from 97% to 105%. As a result, the prepared MMIPs could be applied to selectively pre-concentrate and determine 4-methylimidazole in soy sauce samples.

A hypercrosslinked organic polymer material (named as PPTPA) was prepared by a simple one-step self-polycondensation of triphenylamine. A series of characterization experiments, including N 2 adsorption, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, and thermogravimetric analysis, were carried out to evaluate the morphology, structure and other intrinsic properties of the PPTPA. To investigate its adsorption performance, the PPTPA was used as the solid-phase extraction adsorbent for the extraction of phenylurea herbicides from water, milk and tomato juice samples followed by high-performance liquid chromatographic analysis. Under optimum conditions, good linearity for the analytes was observed in the range of 0.05-40.0ngmL -1 , 0.1-40.0ngmL -1 and 0.5-40.0ngmL -1 for water, milk and tomato juice samples, respectively. The established method also showed low limits of detection (S/N=3) in the range of 0.008-0.01ngmL -1 , 0.01-0.03ngmL -1 and 0.05-0.1ngmL -1 for water, milk and tomato juice samples, respectively. The possible adsorption mechanism of the PPTPA towards the analytes was investigated, and the results demonstrated that the hydrogen bonding was the main interaction force between the PPTPA and the analytes. It suggests that the PPTPA can serve as a promisingadsorbent for the efficient pre-enrichment of organic compounds with more hydrogen-bonding donor sites., (Copyright © 2017. Published by Elsevier B.V.)

This research presents a simple and green in situ solid phase extraction (is-SPE) combined with high-performance liquid chromatography (HPLC) for the simultaneous analysis of tetracyclines (TCs) including tetracycline, oxytetracycline, and chlortetracycline. In is-SPE, TCs were efficiently extracted through the precipitation formation of dissolvable layered double hydroxides (LDHs) by mixing the LDH components such as magnesium and aluminum ions (both in metal chloride salts) thoroughly in an alkaline sample solution. After the centrifugation, the precipitate was completely dissolved with trifluoroacetic acid to release the enriched TCs, and then analyzed by HPLC. Under optimized conditions, this method gave good enrichment factors (EFs) of 41-93 with low limits of detection (LODs) of 0.7-6μg/L and limits of quantitation (LOQs) of 3-15μg/L. Also, the proposed method was successfully applied for the determination of TCs in water and milk samples with the recoveries ranging from 81.7-108.1% for water and 55.7-88.7% for milk., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A magnetic porphyrin-based porous organic polymer (M-PPOP) with good porosity, high surface area and strong magnetism was prepared and employed as the adsorbent for the magnetic solid phase extraction of the phenylurea herbicides (metoxuron, monolinuron, chlorotoluron, and buturon) from bottled grape juice and tomato samples prior to their determination by high performance liquid chromatography. Under the optimized conditions, the developed method exhibited a good linear range, low limits of detection, low relative standard deviations (<6.8%), good method recoveries between 80.8% and 117%, and high enrichment factors (51-106). For a better elucidation of the adsorption of the M-PPOP towards the analytes, the extraction performance of the M-PPOP for different types of organic compounds including polycyclic aromatic hydrocarbons, phenylurea insecticides, phenylurea herbicides and phenols was studied. The results indicated that the π- stacking, hydrogen-bonding and hydrophobic interactions between the M-PPOP and the analytes played a main role for the adsorption. The results revealed that the M-PPOP material had a great potential for the enrichment of more organic pollutants from real samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

As a novel solid-phase extraction material, zinc oxide crystal whiskers were used to extract flavonoid compounds and showed good extraction abilities. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and surface area/pore volume characterized the sorbent. The zinc oxide was packed into a solid-phase extraction micro-column and its extraction ability was evaluated by four model flavonoid compounds. The sample loading and elution parameters were optimized and the zinc oxide based analytical method for flavonoids was established. It showed that the method has wide linearities from 1 to 150μg/L and low limits of detection at 0.25μg/L. The relative standard deviations of a single column repeatability and column to column reproducibility were less than 6.8% and 10.6%. Several real samples were analyzed by the established method and satisfactory results were obtained. The interactions between flavonoids and zinc oxide were calculated and proved to be from the Van der Waals' forces between the 4p and 5d orbitals from zinc atom and the neighboring π orbitals from flavonoid phenyl groups. Moreover, the zinc oxide crystal whiskers showed good stability and could be reused more than 50 times under the operation conditions. This work proves that the zinc oxide crystal whiskers are a good candidate for flavonoids enrichment., (Copyright © 2017. Published by Elsevier B.V.)

A novel magnetic solid-phase extraction (MSPE) based method was established for aromatic amino acids (AAAs) selective determination. Central to the method was the adopted extractant. An explored composite of metal organic frameworks (MOFs) and magnetic carbon nanotubes (CNTs) was employed for that, which exhibited superior adsorption affinity and selectivity to AAAs as compared to other amino acids with the mechanisms attributed to multiple hydrogen bonding and π-π electron-donor-acceptor (EDA) interactions. The morphology, structure and magnetic behavior of the composite were characterized and related MSPE procedure was established. Critical extraction conditions including pH, extraction time, temperature and salt addition were investigated and optimized. Subsequently the concentrations of three AAAs tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe) in Lanzhou lily were determined by the composite based MSPE procedure coupled with high performance liquid chromatography-ultraviolet detection (HPLC-UV). The composite provided a superior sample clean-up function and many of the matrix interferences were eliminated, thus ensured AAAs were accurately and efficiently determined. The results showed that the method had good linearities with the linear coefficients above 0.99, desirable recoveries ranged from 88.0% to 96.8% with the RSD less than 5.1%, satisfactory precision and low limits of detection (LODs) which were respectively 0.04, 0.11, and 0.87ng/g for Trp, Tyr and Phe. The composite based MSPE-HPLC-UV method has great potentials for the AAAs selective determination from complex matrix samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A novel method for determination of sodium cyclamate in foods was developed. In this method, a syringe was loaded with the homogeneous mixture of the sample, KMnO 4 powder and silica dispersant and used as a matrix solid phase dispersion (MSPD) reactor. As the reactor was infiltrated with small amounts of concentrated HCl, cyclamate was converted to 2-chlorocyclohexanone quickly and effectively within 5 min and determined by HPLC on a reversed-phase column using UV detection at a wavelength of 310 nm. Comparing with the traditional derivatisation in solution, the better clean-up was provided using on-cartridge derivatisation of MSPD, and much time, labor, and expense were saved. The results showed good linearity (r 2  = 0.9998) over the concentration range of 1-500 mg/L. The limit of detection (LOD) and limits of quantification (LOQ) of the cyclamate were 0.3 mg/L and 1 mg/L respectively. The recoveries ranged from 91.6% to 101.3% with the relative standard deviations (RSDs) in the range of 2.5%-4.3%., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this study, a magnetic graphene-based dispersive solid phase extraction method was developed that was combined with high performance liquid chromatography to determine the residues of fluoroquinolone drugs in foods of animal origin. During the experiments, several parameters possible influencing the extraction performance were optimized (amount of magnetic graphene, sample pH, extraction time and elution solution). This extraction method showed high absorption capacities (>6800ng) and high enrichment factors (68-79-fold) for seven fluoroquinolones. Furthermore, this absorbent could be reused for at least 40 times. The limits of detection were in the range of 0.05-0.3ng/g, and the recoveries from the standards fortified blank samples (bovine milk, chicken muscle and egg) were in the range of 82.4-108.5%. Therefore, this method could be used as a simple and sensitive tool to determine the residues of fluoroquinolones in foods of animal origin., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We present for the first time the application of metal-organic framework (MOF) mixed-matrix disks (MMD) for the automated flow-through solid-phase extraction (SPE) of environmental pollutants. Zirconium terephthalate UiO-66 and UiO-66-NH 2 MOFs with different size (90, 200 and 300nm) have been incorporated into mechanically stable polyvinylidene difluoride (PVDF) disks. The performance of the MOF-MMDs for automated SPE of seven substituted phenols prior to HPLC analysis has been evaluated using the sequential injection analysis technique. MOF-MMDs enabled the simultaneous extraction of phenols with the concomitant size exclusion of molecules of larger size. The best extraction performance was obtained using a MOF-MMD containing 90nm UiO-66-NH 2 crystals. Using the selected MOF-MMD, detection limits ranging from 0.1 to 0.2μgL -1 were obtained. Relative standard deviations ranged from 3.9 to 5.3% intra-day, and 4.7-5.7% inter-day. Membrane batch-to-batch reproducibility was from 5.2 to 6.4%. Three different groundwater samples were analyzed with the proposed method using MOF-MMDs, obtaining recoveries ranging from 90 to 98% for all tested analytes., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Graphene oxide was fabricated by a simple method and applied to magnetic solid-phase extraction. In a pretreatment procedure before the sesamol, sesamin and sesamolin in sesame oil were detected by high performance liquid chromatography. Several parameters affecting the extraction efficiency were investigated, including the type and volume of desorption solvent, desorption time and the amount of sorbent. Under the optimized conditions, the detection limits of sesamol, sesamin, and sesamolin were 0.05μg/g, 0.02μg/g, and 0.02μg/g, respectively. The limits of quantification were all 0.2μg/g. The average recoveries of sesamol, sesamin, and sesamolin were 84.55%, 85.47%, 86.83%, respectively and their relative standard deviations were 1.23%, 1.33%, and 0.84%, respectively., (Copyright © 2016. Published by Elsevier Ltd.)

Polar and hydrophilic properties of hydroxybenzoic acids usually made them coelute with interferences in high performance liquid chromatography (HPLC) analysis. Then selective analysis of them was necessary. Herein, hollow porous ionic liquids composite polymers (PILs) based solid phase extraction (SPE) was firstly fabricated and coupled online with HPLC for selective analysis of hydroxybenzoic acids from complex matrices. Hollow porous PILs were firstly synthesized using Mobil Composition of Matter No. 48 (MCM-48) spheres as sacrificial support, 1-vinyl-3-methylimidazolium chloride (VMIM + Cl - ) as monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Various parameters affecting synthesis, adsorption and desorption behaviors were investigated and optimized. Steady-state adsorption studies showed the resulting hollow porous PILs exhibited high adsorption capacity, fast adsorption kinetics, and excellent specific adsorption. Subsequently, the application of online SPE system was studied by selective analysis of protocatechuic acid (PCA), 4-hydroxybenzoic acid (4-HBA), and vanillic acid (VA) from Pollen Typha angustifolia. The obtained limit of detection (LOD) varied from 0.002 to 0.01μg/mL, the linear range (0.05-5.0μg/mL) was wide with correlation coefficient (R) from 0.9982 to 0.9994, and the average recoveries at three spiking levels ranged from 82.7 to 102.4%, with column-to-column relative standard deviation (RSD) below 8.1%. The proposed online method showed good accuracy, precision, specificity and convenience, which opened up a universal and efficient route for selective analysis of hydroxybenzoic acids from complex samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A magnetic nanocomposite consisting of nanoparticles-polybutylene terephthalate (MNPs-PBT) was electrospun and used as an extracting medium for an on-line μ-solid phase extraction (μ-SPE)-high performance liquid chromatography (HPLC) set-up with an ultraviolet (UV) detection system. Due to the magnetic property of the prepared nanofibers, the whole extraction procedure was implemented under an external magnetic field to enhance the extraction efficiencies. The developed method along with the synthesized nanocomposite were found to be appropriate for the determination of trace levels of selected drugs including furosemide, naproxen, diclofenac and clobetasol propionate in the urine sample. The prepared MNPs-PBT electrospun nanocomposite was characterized using the scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and Fourier transform infrared (FT-IR) spectroscopy. The prepared magnetic fibers showed high porosity, which was another driving force for the extraction efficiency enhancement. Major parameters affecting the extraction efficiency of the selected drugs were optimized. The limits of detections (LOD) of the studied drugs were in the range of 0.4-1.6 μg L(-1) and the limits of quantification (LOQ) were 1-4 μg L(-1) under the optimized conditions. Relative standard deviation (RSD%) for three replicates at three concentration levels of 6, 100 and 400 μg L(-1) were 5.9-8.0% while acceptable linear range with two orders of magnitude was obtained (R(2) = 0.99). The method was validated by the determination of the selected drugs in urine samples and the results indicated that this method has sufficient potential for enrichment and determination of the desired drugs in the urine sample. The relative recovery values were found to be in the range of 78-91%. Implementing the developed on-line μ-SPE method under the external magnetic field induction, led to higher extraction efficiencies for the selected drugs with various diamagnetic properties., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objectives: Development and validation of a sensitive, selective and robust SPE assisted HPLC method for the quantification of fluoroquinolones and nitroimidazoles in human serum and urine using design of experiments methodology., Design and Methods: Design of experiments was employed for method optimization (Box-Behnken design) and robustness testing (Plackett-Burman design). Sample preparation involved a simple solid phase extraction, which offered a satisfactory recovery (≥94%). Analytes were separated on a phenyl hexyl column with mobile phase comprising water, acetonitrile and triethyl amine in ratio of 74:26:0.15 v/v, with a flow rate of 1.1mL/min., Results: Calibration curves were linear over selected range (≥0.995) for all the analytes. The method was sensitive with detection limits of 0.06-0.16μg/mL in serum and urine samples. Inter and intra-day precision data (in terms of %RSD) was found to be less than 7%. Stability studies were carried out to assess freeze thaw, short term and long term stability and all analytes were found to be stable. The method was successfully applied for determination of antimicrobial drugs in spiked serum and urine., Conclusion: The obtained results corroborated the potential of the proposed method for determination of all the four antimicrobial drugs in therapeutic drug monitoring, bioequivalence and drug-drug interaction studies., (Copyright © 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

A method combining solid phase extraction, high performance liquid chromatography, and ultraviolet/evaporative light scattering detection (SPE-HPLC-UV/ELSD) was developed according to Quality by Design (QbD) principles and used to assay nine bioactive compounds within a botanical drug, Shenqi Fuzheng Injection. Risk assessment and a Plackett-Burman design were utilized to evaluate the impact of 11 factors on the resolutions and signal-to-noise of chromatographic peaks. Multiple regression and Pareto ranking analysis indicated that the sorbent mass, sample volume, flow rate, column temperature, evaporator temperature, and gas flow rate were statistically significant (p < 0.05) in this procedure. Furthermore, a Box-Behnken design combined with response surface analysis was employed to study the relationships between the quality of SPE-HPLC-UV/ELSD analysis and four significant factors, i.e., flow rate, column temperature, evaporator temperature, and gas flow rate. An analytical design space of SPE-HPLC-UV/ELSD was then constructed by calculated Monte Carlo probability. In the presented approach, the operating parameters of sample preparation, chromatographic separation, and compound detection were investigated simultaneously. Eight terms of method validation, i.e., system-suitability tests, method robustness/ruggedness, sensitivity, precision, repeatability, linearity, accuracy, and stability, were accomplished at a selected working point. These results revealed that the QbD principles were suitable in the development of analytical procedures for samples in complex matrices. Meanwhile, the analytical quality and method robustness were validated by the analytical design space. The presented strategy provides a tutorial on the development of a robust QbD-compliant quantitative method for samples in complex matrices.

A novel and efficient sample preconcentration technique based on the Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) coated with silica (SiO2) has been developed for extraction and determination of sulpiride. The functionalized MNPs showed excellent dispersibility in aqueous solution and were applied to magnetic solid-phase extraction of sulpiride from human urine and blood prior to high-performance liquid chromatography analysis. The separation, preconcentration and desorption procedure was completed in 10 min. Optimal experimental conditions, including sample pH, the amount of the MNPs, eluent type and volume, and the ultrasonication time were studied and established. The method showed good linearity for the determination of sulpiride in the concentration range of 10-1000 ng/mL in urine and blood. The recovery of the method was in the range between 91.2 and 97.5%, and the limit of detection was 2 ng/mL for sulpiride in human blood and urine. The results indicated that the present procedure is a suitable pretreatment method for biological samples., (Copyright © 2015 John Wiley & Sons, Ltd.)

In the present study, a graphene-based magnetic nanocomposite (CoFe2O4-graphene, CoFe2O4-G) was synthesized and used successfully as an adsorbent for the magnetic solid phase extraction (MSPE) of sulfonamides for the first time. The surface morphologies and structures of the CoFe2O4-G nanocomposite were investigated by scanning electron microscopy (SEM), FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD) and vibration sample magnetometer (VSM). Five sulfonamides, including sulfamerazine, sulfamethizole, sulfadoxine, sulfamethoxazole and sulfisoxazole were used as model analytes to evaluate the enrichment properties of the prepared adsorbent in MSPE. After preconcentration, the adsorbent could be conveniently separated from the aqueous samples by an external magnet, and the analytes desorbed from adsorbent were determined by high performance liquid chromatography-ultraviolet detection (HPLC-UV). Extraction parameters including sample pH, amount of sorbent, extraction time and desorption conditions were optimized in detail. Under the optimal conditions, good linear relationships between the peak areas and the concentrations of the analytes were obtained. The linear ranges were 0.02-50.00 mg L(-1) with correlation coefficients (r)≧0.9982. The limits of detection were less than 1.59 μg L(-1). Good reproducibility was obtained. The relative standard deviations of intra- and inter-day analysis were less than 4.3% and 6.5%, respectively. The proposed method was successfully applied for the analysis of sulfonamides in milk samples. The average recoveries determined for two milk samples spiked at levels from 5 to 20 μg L(-1) were 62.0-104.3% with relative standard deviations less than 14.0%. In addition, the CoFe2O4-G could be reused after cleaning with acetone and ultrapure water successively., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In this work, a simple method for the extraction and analysis of bisphenols in environmental samples was presented. And the prepared zirconium-based magnetic MOFs (magG@PDA@Zr-MOF) were used as the sorbents for the magnetic solid-phase extraction. With the simple solvothermal reaction and sol-gel method, the prepared material showed great characteristics of large surface area, homogeneous pore size, good magnetic responsivity and super-hydrophilicity. The large surface area provided abundant sites to extract target compounds; the magnetic property could simplify the whole extraction procedure; and the hydrophilicity improved the dispersibility of the material in matrix. Here, various extraction parameters were optimized, including amounts of sorbents, adsorption time, species of elution solvents and desorption time. The whole extraction procedure could be accomplished in 30 min. And under the optimized conditions, method validations were also studied, such as linearity, the limit of detection and recovery. Finally, the prepared material was used in real water samples. The results showed this material had good potential as the sorbent for the extraction of targets in environmental water samples., (Copyright © 2015 Elsevier B.V. All rights reserved.)