Room-temperature synthesis of dual-functionalized magnetic microporous organic network for efficient extraction of vanillins in food

Fabrication of sea urchin shaped polyaniline-modified magnetic microporous organic network for efficient extraction of non-steroidal anti-inflammatory drugs from animal-derived food samples

In this work, a novel polyaniline-modified magnetic microporous organic network (MMON-PANI) composite was fabricated for effective magnetic solid phase extraction (MSPE) of five typical nonsteroidal anti-inflammatory drugs (NSAIDs) from animal-derived food samples before high performance liquid chromatography (HPLC) detection. The core-shell sea urchin shaped MMON-PANI integrates the merits of Fe3O4, MON, and PANI, exhibiting large specific surface area, rapid magnetic responsiveness, good stability, and multiple binding sites to NSAIDs. Convenient and effective extraction of trace NSAIDs from chicken, beef and pork samples is realized on MMON-PANI via the synergetic π-π, hydrogen bonding, hydrophobic, and electrostatic interactions. Under optimal conditions, the MMON-PANI-MSPE-HPLC-UV method exhibits wide linear ranges (0.2-1000 μg L-1), low limits of detection (0.07-1.7 μg L-1), good precisions (intraday and inter-day RSDs < 5.4 %, n = 3), large enrichment factors (98.6-99.9), and less adsorbent consumption (3 mg). The extraction mechanism and selectivity of MMON-PANI are also evaluated in detail. This work proves the incorporation of PANI onto MMON is an efficient way to promote NSAIDs enrichment and provides a new strategy to synthesize multifunctional MON-based composites in sample pretreatment.

Preparation of cationic microporous organic network for efficient solid-phase extraction of nonsteroidal anti-inflammatory drugs from environmental water and milk samples

The overuse of nonsteroidal anti-inflammatory drugs (NSAIDs) poses many serious environmental and food safety concerns. Development of effective and sensitive sample pretreatment method for monitoring trace NSAIDs from complex samples is of great significance. Depending on the ionic and aromatic structures of NSAIDs, a cationic microporous organic network (MON) named TEPM-BBDC with large specific surface area, good solvent and thermal stabilities, and numerous interaction sites was designed and prepared for efficient solid-phase extraction (SPE) of four typical NSAIDs (flurbiprofen, ketoprofen, naproxen, and diclofenac sodium) from environmental water and milk samples. By anchoring the ionic groups in the conjugated MON frameworks, the prepared TEPM-BBDC offered good extraction for NSAIDs based on the π-π, hydrophobic, ion exchange, and electrostatic interactions. Under the optimal extraction conditions (initial concentration of each NSAID: 200 g L-1; sample volume: 50 mL; desorption solvent: 1.5 mL of MeOH + 1 % NH3·H2O; sample loading rate: 5 mL min-1; NaCl concentration: 0 mmol L-1; pH = 5), the proposed TEPM-BBDC-SPE-HPLC-UV method owned wide linear range (0.50-1000 g L-1), low limits of detection (0.10-0.40 g L-1), large enrichment factors (92.2-99.2), good precisions (intra-day and inter-day, RSD% = 1.3-7.8 %, n = 6) and reproducibility (column-to-column, RSD% = 8.0 %, n = 3). The developed method also exhibited good recoveries (83.6-113.4 %) for the determination of NSAIDs in river water, lake water and milk samples. This work not only revealed the potential of TEPM-BBDC for SPE of ionic NSAIDs in complex samples, but also highlighted the prospect of ionic MONs in sample pretreatment.

Dispersive solid-phase extraction based on zirconium metal-organic framework coupled with gas chromatography-mass spectrometry for determining sugar phosphates in biological samples

BACKGROUND

Sugar phosphates (SPx) play important role in the metabolism of the organism. SPx such as glycerate 3-phosphate, fructose 6-phosphate and glucose 6-phosphate in biological samples have the poor stability, similar structure and low abundance, which make their separation and detection more challenging.

METHOD

UiO-66-NH2 and ZrO2 coated SiO2(SBA-15) hard-core-shell adsorbents (UiO-66-NH2@SBA-15 and ZrO2@SBA-15) were synthesized, which were further used for dispersive solid-phase extraction for enriching the SPx in biological samples. The protocol was developed by UiO-66-NH2@SBA-15 and ZrO2@SBA-15 coupled with gas chromatography-mass spectrometry for the detection of trace SPx. The univariate experiment and response surface methodology were used to optimize the adsorption and desorption conditions.

RESULTS

The adsorbents showed excellent adsorption capacity and specificity towards SPx, which were proved by adsorption and selective experiments. Under the optimized conditions, there were good linearity within the range of 5.0-5000.0 ng mL-1, low limits of detection (0.001-1.0 ng mL-1), low limits of quantification (0.005-5.0 ng mL-1) and good precision (relative standard deviation less than 14.7 % for intra-day and inter-day). The satisfactory recoveries (89.1-113.8 %) and precision (0.5-14.6 %) were obtained when the sorbents were used to extract SPx from serum, saliva and cell samples. Moreover, UiO-66-NH2@SBA-15 was applied to the quantitative analysis of SPx from gastric cancer patients, because of a higher adsorption capacity (169.5-196.1 mg g-1).

CONCLUSIONS

UiO-66-NH2@SBA-15 showed great potential in the extraction of SPx in biological samples, which was beneficial to find out the metabolic change of SPx and explain the pathogenesis of the disease.

Electrochemical chiral sensor for recognition of amino acid enantiomers with cyclodextrin-based microporous organic networks

BACKGROUND

Chirality is a ubiquitous phenomenon in nature, but enantiomers exhibit different pharmacological activities and toxicological effects. Therefore, Chiral recognition plays a pivotal role in various fields such as life sciences, chemical synthesis, drug development, and materials science. The synthesis of novel chiral composites with well-defined loading capabilities and ordered structures holds significant potential for electrochemical chiral recognition applications. However, the design of selective and stable electrochemical chiral recognition materials remains a challenging task.

RESULT

In this work, we construct a simple and rapid electrochemical sensing platform for tryptophan (Trp) enantiomer recognition using cyclodextrin-modified microporous organic network as chiral recognition agent. CD-MON with chiral microenvironment was prepared by Sonogashira-Hagihara coupling reaction of the chiral molecule heptyl-6-iodo-6-deoxyβ-cyclodextrin and 1, 4-Diethynylbenzene. The adhesion of BSA makes CD-MON firmly fixed on the electrode surface, and as a chiral protein, it can improve the chiral recognition ability through synergistic effect. Chiral amino acids are in full contact with the chiral microenvironment during pore conduction of MON, and L-Trp is more stably bound to CD-MON/BSA due to steric hindrance, host-guest recognition and hydrogen bonding. Therefore, the electrochemical sensor can effectively identify tryptophan enantiomers (IL-Trp/ID-Trp = 2.02), and it exhibits a detection limit of 2.6 μM for L-Trp. UV-Vis spectroscopy confirmed the adsorption capacity of CD-MON towards tryptophan enantiomers in agreement with electrochemistry results.

SIGNIFICANCE

The prepared chiral sensor has excellent stability, reproducibility (RSD = 3.7%) and selectivity, realizes the quantitative detection of single isomer in tryptophan racemic and quantitative analysis in real samples with 94.0%-101.0% recovery. This work represents the first application of MON in chiral electrochemistry which expands the application scope of chiral sensors and holds great significance in separation science and electrochemical sensing.

Fabrication of fluorinated magnetic microporous organic network for selective and efficient extraction of benzoylurea insecticides in tea beverages

In this work, a novel fluorinated magnetic microporous organic network (Fe3O4@FMON) was exquisitely designed and synthesized for highly efficient and selective magnetic solid phase extraction (MSPE) of fluorinated benzoylurea insecticides (BUs) from complex tea beverage samples. The Fe3O4@FMON exhibited good extraction for BUs via the pre-designed hydrophobic, π-π stacking, hydrogen bonding and specific FF interactions. A sensitive Fe3O4@FMON-based MSPE-HPLC-UV method with wide linear range (0.10-1000 μg L-1, R2 ≥ 0.996), low limits of detection (0.01-0.02 μg L-1), and large enrichment factors (85.6-98.0) for BUs from tea beverage samples was developed. By decorating F elements within MON's networks, the Fe3O4@FMON characterized good hydrophobicity and chemical stability, which could be reused at least 8 times without decrease of recoveries. This work demonstrated the great prospects of Fe3O4@FMON for enriching trace BUs from complex substrates and triggered the potential of FMON for sample pretreatment of fluorinated analytes.

Facile preparation of covalent-organic framework composites for magnetic solid-phase extraction of naphthaleneacetic acid in food prior to HPLC-UV analysis

Novel magnetic covalent organic frameworks (COFs) were prepared by one-pot synthetic strategy and employed as an efficient adsorbent for magnetic solid-phase extraction (MSPE) of naphthaleneacetic acid (NAA) in food samples. Depending on the predesigned the hydrogen bonding, π-π and hydrophobic interactions of magnetic COFs, the efficient and selective extraction process for NAA was achieved within 15 min. The magnetic COFs adsorbent combined with HPLC-UV was devoted to develop a novel quantitative method for NAA in complex food. The method afforded good coefficient in range of 0.002-10.0 µg mL-1 and low limit of detection was 0.0006 µg mL-1. And the newly established method afforded less adsorbent consumption, wider linearity and lower LODs than the reported analytical methods. Ultimately, the method was successfully applied to determine NAA in fresh pear, tomato and peach juice. The magnetic COFs based MSPE coupled with HPLC-UV method provided a simple, efficient and dependable alternative to monitor trace NAA in food samples.

Fabrication of amino- and hydroxyl dual-functionalized magnetic microporous organic network for extraction of zearalenone from traditional Chinese medicine prior to the HPLC determination

Efficient enrichment of trace zearalenone (ZEN) from the complex traditional Chinese medicine (TCM) samples is quite difficult, but of great significance for TCM quality control. Herein, we reported a novel magnetic solid phase extraction (MSPE) strategy for ZEN enrichment using the amino- and hydroxyl dual-functionalized magnetic microporous organic network (Fe3O4@MON-NH2-OH) as an advanced adsorbent combined with the high-performance liquid chromatography (HPLC) determination. Efficient extraction of ZEN was achieved via the possible hydrogen bonding, hydrophobic, and π-π interactions between Fe3O4@MON-NH2-OH and ZEN. The adsorption capacity of Fe3O4@MON-NH2-OH for ZEN was 215.0 mg g-1 at the room temperature, which was much higher than most of the reported adsorbents. Under the optimal condition, the developed Fe3O4@MON-NH2-OH-MSPE-HPLC method exhibited wide linear range (5-2500 μg L-1), low limits of detection (1.4-35 μg L-1), less adsorbent consumption (5 mg), and large enhancement factor (95) for ZEN. The proposed method was successfully applied to detect trace ZEN from 10 kinds of real TCM samples. Conclusively, this work demonstrates the Fe3O4@MON-NH2-OH can effectively extract trace ZEN from the complex TCM matrices, which may open up a new way for the application of MONs in the enrichment and extraction of trace contaminants or active constituents from the complex TCM samples.

High-Performance enrichment and sensitive analysis of bisphenol and its analogues in water and milk using a novel Ni-Based cationic Metal-Organic framework

A novel cationic metal-organic framework (iMOF-Ni) was designed and synthesized by a solvothermal method. It was fabricated as a solid-phase extraction (SPE) cartridge and exhibited high adsorption performance for Bisphenols (BPs). The theoretical simulation demonstrated that the adsorption mechanism between iMOF-Ni and BPs was attributed to cation-π bonding, π-π interaction, and electrostatic interactions. Under optimized SPE, a method for analyzing BPs was established by combining high-performance liquid chromatography-diode array detection (HPLC-DAD). The developed method has good linearity (R2 ≥ 0.994), low detection limits (0.07-0.16 ng/mL), and good reproducibility (1.72-6.35 %, n = 6). The applicability of the method was further evaluated by analyzing water and milk samples. Recoveries of four BPs in spiked samples were from 72.2 % to 96.6 %.

Sacrificial template synthesis of hollow sulfonate group functionalized microporous organic network for efficient solid phase extraction of sulfonamide antibiotics from milk and honey samples

The highly conjugated and hydrophobic characteristics of microporous organic networks (MONs) have largely impeded their broad applications in sample pretreatment especially for the polar or ionic analytes. In this work, a novel uniform hollow shaped sulfonate group functionalized MON (H-MON-SO3H-2) was synthesized via the sacrificial template method for the efficient solid phase extraction (SPE) of sulfonamides (SAs) from environmental water, milk, and honey samples prior to HPLC analysis. H-MON-SO3H-2 exhibited large specific surface area, penetrable space, good stability, and numerous hydrogen bonding, electrostatic, hydrophobic and π-π interaction sites, allowing sensitive SPE of SAs with wide linear range (0.150-1000 μg L-1), low limit of detection (0.045-0.188 μg L-1), good precisions (intra-day and inter-day RSD < 7.3%, n = 5), large enrichment factors (95.7-98.5), high adsorption capacities (250.4-545.0 mg g-1), and satisfactory reusability (more than 80 times). Moreover, the established method was successfully applied to extract SAs from spiked samples with the recoveries of 86.1-104.3%. This work demonstrated the great potential of H-MON-SO3H-2 in the efficient SPE of trace SAs in complex environmental water and food samples and revealed the prospect of hollow MONs in sample pretreatment.