Hydroxylated hierarchical flower-like COF for solid-phase extraction of adrenergic receptor agonists in milk.

A new detection platform based on a hydroxylated covalent organic framework (COF) integrated with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was constructed and used for detecting adrenergic receptor agonists (ARAs) residues in milk. The hydroxylated COF was prepared by polymerization of tris(4-aminophenyl)amine and 1,3,5-tris(4-formyl-3-hydroxyphenyl)benzene and applied to solid-phase extraction (SPE) of ARAs. This hydroxylated COF was featured with hierarchical flower-like morphology, easy preparation, and copious active adsorption sites. The adsorption model fittings and molecular simulation were applied to explore the potential adsorption mechanism. This detection platform was suitable for detecting four α2- and five ß2-ARAs residues in milk. The linear ranges of the ARAs were from 0.25 to 50 µg·kg-1; the intra-day and the inter-day repeatability were in the range 2.9-7.9% and 2.0-10.1%, respectively. This work demonstrates this hydroxylated COF has great potential as SPE cartridge packing, and provides a new way to determine ARAs residues in milk.

Application Value of Sevoflurane Combined with Brachial Plexus Block in Children with Humeral Fracture Surgery and its Effect on Hemodynamics: A Clinical and Anatomical Study

SUMMARY: To observe the effect of sevoflurane combined with brachial plexus block (BPB) in children with humeral fracture surgery and its effect on hemodynamics. 84 children who received surgical treatment of humeral fracture in our hospital from September 2019 to September 2022 were selected. According to different anesthesia methods, the children were divided into control group and study group. The control group only received laryngeal mask sevoflurane; the study group received laryngeal mask sevoflurane combined with BPB. The operation situation, hemodynamic indexes, stress level, pain and adverse reactions of children was observed. The postoperative awakening time in the study group was lower than control group, the postoperative pain onset time in the study group was higher than control group (P0.05). Postoperative 2h, the levels of serum cortisol, b-endorpin, norepinephrine and epinephrine in the study group were lower than control group (P0.05). Sevoflurane combined with BPB is helpful to shorten the postoperative awakening time of children with humeral fracture, reduce the degree of postoperative pain, improve hemodynamics, and reduce stress response, and has good safety.

El objetivo fue observar el efecto del sevoflurano combinado con bloqueo del plexo braquial (BPB) en niños con cirugía de fractura de húmero y su efecto sobre la hemodinámica. Se seleccionaron 84 niños que recibieron tratamiento quirúrgico de fractura de húmero en nuestro hospital desde septiembre de 2019 hasta septiembre de 2022. Según diferentes métodos de anestesia, los niños se dividieron en grupo control y grupo de estudio. El grupo control solo recibió sevoflurano en mascarilla laríngea; el grupo de estudio recibió sevoflurano con mascarilla laríngea combinado con BPB. Se observó la situación operatoria, índices hemodinámicos, nivel de estrés, dolor y reacciones adversas de los niños. El tiempo hasta el despertar postoperatorio en el grupo de estudio fue menor que el del grupo control, el tiempo de aparición del dolor postoperatorio en el grupo de estudio fue mayor que el del grupo control (P0,05). A las 2 horas postoperatorias, los niveles séricos de cortisol, β-endorfina, norepinefrina y epinefrina en el grupo de estudio fueron más bajos que los del grupo control (P 0,05). El sevoflurano combinado con BPB es útil para acortar el tiempo de despertar del posoperatorio de los niños con fractura de húmero, reduce el grado de dolor postoperatorio, mejora la hemodinámica y reduce la respuesta al estrés, además de tener buena seguridad.

A dual-mode nanoprobe based on silicon nanoparticles and Fe(II)-phenanthroline for the colorimetric and fluorescence determination of nitrite.

A fluorometric and colorimetric dual-modal nanoprobe (denoted as Fe2+-Phen/SiNPs) has been developed for selective and sensitive determination of nitrite (NO2-). The mechanism is based on fluorescence quenching between silicon nanoparticles (SiNPs) and Fe(II)-phenanthroline complex (Fe2+-Phen) via inner filter effect and redox. With the addition of increasing NO2-, Fe2+ is oxidized to Fe3+, recovering the fluorescence of SiNPs. Meanwhile, the color of the system gradually changes from orange-red to colorless, which enables colorimetric measurement. The NO2- concentration shows a wide linear relationship with fluorescence intensity from 0.1 to 1.0 mM (R2 = 0.9955) with a detection limit of 2.4 µM in the fluorometric method (excitation wavelength: 380 nm). By contrast, the linear range of the colorimetric method ranges from 0.01 to 0.35 mM (R2 = 0.9953) with a limit of detection of 6.8 µM (proposed selective absorbance: 510 nm). The probe has been successfully applied to nitrite determination in water, salted vegetables, and hams demonstrating broad application prospects for the determination of nitrite in complicated matrices.

Au@BN-enhanced laser desorption/ionization mass spectrometry and imaging for determination of fipronil and its metabolites in food and biological samples.

Gold nanoparticles (AuNPs) represent an attractive inorganic matrix for laser desorption/ionization mass spectrometry (LDI-MS) detection of low-molecular-weight analytes; however, their direct use is hindered by severe aggregation. To limit AuNPs aggregation, hexagonal boron nitride nanosheets (h-BNNs) were employed as supports to improve their desorption/ionization efficiency. Thus, Au@BN was synthesized and systematically characterized. It showed low background noise and high sensitivity for LDI-MS of fipronil and its metabolites. Au@BN-assisted LDI-MS was validated using complex samples including blueberry juice, green tea beverage, and fish muscle, achieving low detection limits (0.05-0.20 µg·L-1 for liquid media, 0.82-1.25 ng·g-1 for fish muscle), wide linear ranges (0.2-100 µg·L-1 for liquid media, 3.00-1000 ng·g-1 for fish muscle), high reproducibility (7.55%-13.7%), and satisfactory recoveries (82.62%-109.1%). Furthermore, spatial distributions of analytes in strawberries and zebrafish were successfully imaged. This strategy allows for the quantitative analysis of other small molecules in complex substrates.

Three-dimensional hydroxylated covalent organic frameworks for solid phase extraction of glucocorticoids in environmental water samples.

It is challenging to achieve the highly sensitive detection of glucocorticoids at ultratrace levels because of the abundant hydrophilic groups in their molecules and the complexity of environmental water sample matrices. Here, a highly crystalline three-dimensional hydroxylated covalent organic frameworks (denoted by COF-301) with tetra(4-anilyl)methane (TAM) and 2,5-dihydroxyterephthalaldehyde (DHTA) as building units was constructed and proposed as adsorbent for solid phase extraction (SPE) of glucocorticoids. Theoretical studies were conducted to elucidate the potential adsorption mechanism of glucocorticoids on the COF-301. The COF-301 based SPE combined with liquid chromatography-tandem mass spectrometry provides a promising approach for the preconcentration and determination of glucocorticoids residue in water samples. Good linearity with a correlation coefficient exceeding 0.9988, low limits of detection ranging from 0.024 to 0.075 ng L-1 and relative standard deviations below 6.68% were achieved. The proposed method was successfully applied to analyze glucocorticoids residue in actual water samples, demonstrating the prospects of this method for the determination of trace glucocorticoids.

Determination of trace phenoxy carboxylic acid herbicides in environmental water samples by covalent organic frameworks based solid phase extraction coupled with liquid chromatography-tandem mass spectrometry.

The determination of traces levels of pesticide residue in water is crucial for monitoring water quality. In this study, covalent organic frameworks (COFs), namely TAPA-TFPB-COFs were prepared at room temperature (25 °C) and applied as adsorbents for the solid phase extraction (SPE) of phenoxy carboxylic acid herbicides (PCAs). The extraction was followed by analyzation using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under the optimal conditions, ultrasensitive and specific analysis of PCAs in water samples was achieved. The method exhibited high sensitivity with low limits of detection (0.08-0.28 ng L-1), good linearity in the range of 1.00 to 200 ng L-1 and satisfactory repeatability (intra-day: 3.72-5.30%; inter-day: 2.02-4.04%). The method was successfully applied to the analyzation of trace PCAs in tap, well, and river water and the spiked recoveries were in the range of 81.1-112%. These results indicate that the SPE-LC-MS/MS technique with TAPA-TFPB-COFs as the SPE adsorbent is a promising technique for the detection of trace levels of PCAs in environmental water samples.

Fluorinated boron nitride nanosheets as an inorganic matrix for the MALDI mass spectrometry analysis of perfluoroalkyl acids.

We report, for the first time, the application of fluorinated hexagonal boron nitride nanosheets (F-BNNs) as an effective inorganic matrix for matrix-assisted laser desorption and ionization mass spectrometry (MALDI-MS) analysis of perfluoroalkyl acids (PFAAs). Fluoride modification of F-BNNs increases both enrichment ability and ionization efficiency. The method was validated using environmental water, milk, human serum samples, and zebrafish imaging that has been previously exposed to PFAAs. The method provided in this work holds considerable promise in term of rapid analysis, sample requirement, and practicability.

Cationic covalent organic nanosheets for rapid and effective detection of phenoxy carboxylic acid herbicides residue emitted from water and rice samples.

Development of efficient and sensitive adsorbent for capturing phenoxy carboxylic acids (PCAs) from environmental and food samples is necessary because PCAs could threaten human health. Designing nanoparticle with multiple functional groups is beneficial to achieve the strong adsorption interaction and the specific recognition for target compound. In this paper, TpTGCl as an ionic covalent organic framework (ICOF), that could offer plenty of positive charges and hydrogen-bonding sites, was fabricated. TpTGCl achieved quicker, more sensitive enrichment for anionic PCAs. The analysis of binding affinity by density functional theory (DFT) demonstrated that PCAs bonded to TpTGCl primarily via electrostatic attraction, N  H···O and O  H···O, and C  H···π interaction. The quantitative approach indicated low limits of detection (0.016-0.036 ng·g-1 for rice and 0.43-0.78 ng·L-1 for water). Furthermore, successfully determining PCAs emitted from real samples indicated the applicability of TpTGCl.

Fabrication of a Magnetic Fluorinated Covalent Organic Framework for the Selective Capture of Benzoylurea Insecticide Residue in Beverages.

Efficient capture of benzoylurea insecticide (BU) residue in food is a vital procedure for food safe monitoring. Herein, a core-shell structured magnetic fluorinated covalent organic framework with good magnetic responsiveness and abundant fluorine affinity sites was successfully synthesized, suitable for magnetic solid-phase extraction (MSPE) of BUs. Using a room-temperature synthesis strategy, the magnetic fluorinated covalent organic framework was fabricated by in situ polymerization of 1,3,5-tris(4-aminophenyl) triazine (TAPT) and 2,3,5,6-tetrafluoroterephthaldehyde (TFTA) on the surface of carboxylated Fe3O4 nanoparticles. The competitive adsorption experiment and molecular simulation verified that this magnetic fluorinated covalent organic framework possesses favorable adsorption affinity for BUs. This magnetic fluorinated covalent organic framework could be easily regenerated and reused at least eight times with no reduction of enrichment performance. Combining this magnetic fluorinated covalent organic framework-based MSPE with high-performance liquid chromatography-tandem mass spectrometry, a novel sensitive method for the analysis of BUs was developed. In yellow wine and fruit juice samples, good linear correlations were obtained for BUs in the range of 10-2000 and 20-4000 ng·L-1, respectively. The limit of quantitation of the BUs ranged from 1.4 to 13.3 ng·L-1 in the two beverage matrices. Desirable precision was achieved, with intraday and interday relative standard deviations lower than 11%.

Ketoenamine Covalent Organic Framework Coating for Efficient Solid-Phase Microextraction of Trace Organochlorine Pesticides.

Fiber coating is a key part of solid-phase microextraction (SPME) technology, and it determines the selectivity, sensitivity, and reproducibility of the analytical method. A ketoenamine covalent organic framework called Tp-Azo-COF with rich electronegative N atoms was prepared as an SPME coating in this work. The Tp-Azo-COF coating had a large surface area of 1218 m2 g-1 and good thermal and chemical stability, and it was applied for the extraction of organochlorine pesticides (OCPs). According to quantum chemistry calculations, the adsorption affinity of the Tp-Azo-COF coating for five OCPs was primarily affected by the halogen bond and hydrophobicity interaction. The extraction efficiencies of the Tp-Azo-COF coating for five OCPs were higher than those of three commercial SPME fiber coatings, and the enrichment factors ranged from 1061 to 3693. When combined with gas chromatography-tandem mass spectrometry, a wide linear range (0.1-1000 ng L-1), low limits of detection (0.002-0.08 ng L-1), and good fiber-to-fiber accuracy (4.3-10.9%) were achieved under optimal conditions. Moreover, the applicability of the developed method was evaluated by analyzing four samples (milk, green tea, tap water, and well water), and the recoveries were in the range of 83.4-101.6%, with relative standard deviations <8.6%. This research extends the application of the stabilized ketoenamine COF as a sample enrichment probe for OCP analysis.

High crystalline magnetic covalent organic framework with three-dimensional grapevine structure for ultrasensitive extraction of nitro-polycyclic aromatic hydrocarbons in food and environmental samples.

Developing and establishing an efficient pre-treatment approach for the precise extraction of nitrated-polycyclic aromatic hydrocarbons (N-PAHs) from real-life samples is critical for ensuring their safety. In this study, a novel crystalline magnetic covalent organic framework with a grapevine structure not a single core-shell, Fe3O4@TAPT-DMTA-COF, was fabricated via chemical bonding. Unchanging the reticulated structure and high crystallinity of TAPT-DMTA-COF, the combination made this material possess not only simple operation via magnetic decantation but also remarkable chemical stability. Fe3O4@TAPT-DMTA-COF had a large surface area (1578.45 m2/g), and rich electronegative triazine-groups, which makes it become a superior magnetic enrichment material for trace N-PAHs. For N-PAHs analysis, low limits of detection (LODs) (1.43-17.24 ng/L), excellent relative standard deviations (RSDs ≤ 11.52%), and wide linearity (10-5000 ng/L) were obtained. Real-life applications based on this composite have been successfully explored by capturing the N-PAHs emitted from food and environmental samples.

Magnetic boron nitride nanosheets as a novel magnetic solid-phase extraction adsorbent for the determination of plant growth regulators in tomatoes.

A novel magnetic boron nitride nanosheets (Fe3O4@BNNSs) composite-based magnetic solid-phase extraction (MSPE) method was employed to analyse six plant growth regulators (PGRs) in tomatoes combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The novel Fe3O4@BNNSs composite was prepared via an in situ chemical coprecipitation process and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Several factors that may affect the extraction efficiencies were optimized. Under the optimal factors, low limits of detection (0.002-0.010 ng g-1), good linear ranges (0.05-10 ng g-1) and satisfactory precisions (intra-day: 1.2%-3.9%; inter-day: 2.1%-6.9%) were achieved. The established approach was successfully employed to extract and determine PGRs in tomatoes, and the spiked recoveries were between 85.2 and 109.0%.

Room-temperature synthesis of magnetic covalent organic frameworks for analyzing trace benzoylurea insecticide residue in tea beverages.

A novel magnetic covalent organic framework (NH2-Fe3O4@COF) was prepared using a simple room-temperature synthesis in this study. These magnetic particles exhibited high adsorption performance with short adsorption time (10 min) for six benzoylurea insecticides (BUs) as magnetic solid-phase extraction (MSPE) adsorbents. Quantum chemistry calculation demonstrated that adsorption mechanism was primarily attributed to strong halogen bonds between electronegative O atoms of COF and electropositive F atoms of BUs as well as potential hydrophobic effect. Wide linearities (10-1000 ng·L-1) and low limits of detection (0.06-1.65 ng·L-1) for six analytes were obtained via liquid chromatography-tandem mass spectrometry. Applicability of the proposed method was further evaluated by analyzing four kinds of original tea beverages. Recoveries of six BUs in spiked samples ranged from 80.1% to 108.4%.

Triazine-cored covalent organic framework for ultrasensitive detection of polybrominated diphenyl ethers from real samples: Experimental and DFT study.

Food and environmental safety issues attributable to the polybrominated diphenyl ethers (PBDEs) are gaining increasing attention, and these urge us to establish a high-performance sample-handling technique. In this study, an outstanding adsorption performance with short adsorption time (10 min) was achieved for PBDEs using a novel synthesized dispersive solid-phase extraction adsorbent, a reticulated covalent organic framework with N/O functional groups (i.e., imine linkage, triazine, and methoxy) (TAPT-DMTA-COF). By conducting sufficient experimentation and theoretical simulation on adsorption mechanism, the halogen bond between electronegative N/O atoms of TAPT-DMTA-COF and the electropositive Br atoms of PBDEs were observed to play a more pivotal role than π-π, C-H…π interactions, and hydrophobic effects. Furthermore, the positive linear relation between calculated adsorption energy and Br content directly clarified that enrichment behavior of PBDEs can be attributed to halogen bonding. These data implied that integrated nanostructure (i.e., N/O functional groups and reticulated architecture) effectively enhanced adsorption capacity. In case of PBDE analysis, this approach achieved excellent results with low limits of detection (0.03-0.13 ng L-1). Finally, the promising potential applications of aforementioned method were verified by spiking water, fish, and milk samples with PBDEs; good PBDEs recoveries were obtained.

Facile preparation of hydroxyl bearing covalent organic frameworks for analysis of phenoxy carboxylic acid pesticide residue in plant-derived food.

The development of sensitive method for analysis ofpesticide residue is of great significance to ensure food safety and promote globalization of food trade. An original method was proposed for analysis of phenoxy carboxylic acids (PCAs) pesticide in plant-derived food. To concentrate trace PCAs, the TAPT-DHTA-COF was fabricated by a facile room-temperature method and utilized as the solid phase extraction cartridge packing. The TAPT-DHTA-COF exhibited excellent adsorption capacity and recyclability towards PCAs. Theoretical simulation indicated that the adsorption of PCAs onto the TAPT-DHTA-COF was driven by hydrogen bond, halogen bond and π-π interaction. Using liquid chromatography tandem mass spectrometry for detection, good linearity ranged from 0.10 to 40 ng·g-1 and low limits of detection varied from 0.007 to 0.030 ng·g-1 were achieved for PCAs in rice, apple and greengrocery. The recoveries of PCAs from the spiked samples ranged from 81.2% to 107%. The reliability was verified by the accurate determination of certified reference materials.

Room-temperature synthesis of flower-shaped covalent organic frameworks for solid-phase extraction of quinolone antibiotics.

The facile fabrication of covalent organic frameworks (COFs) is significant for exploring and promoting their application. In this study, TAPA-TFPB-COFs with flower-shaped morphology, good crystallinity, and high surface area was prepared via a facile room-temperature method. The as-synthesized TAPA-TFPB-COFs exhibited great adsorption capacity towards quinolone antibiotics (QAs) and satisfying reusability. Utilizing the TAPA-TFPB-COFs as solid-phase extraction cartridge packing and liquid chromatography-tandem mass spectrometry as detector, a reliable and ultrasensitive method for the assay of QAs was developed. The linearity ranges of QAs extended from 0.5 to 200 ng L-1 with correlation coefficients higher than 0.9974, and the limits of detection varied from 0.02 to 0.11 ng L-1. The intra-day and inter-day precision were lower than 10.8% and 6.7%, respectively. The applicability of the developed method was evaluated through analyzing of tap water, spring water, chicken, and fish samples. The recoveries of QAs in spiked water and food samples varied from 80.0% to 107.6%. The reliability of the developed method was further verified by the accurate detection of QAs in a fish certified reference material.

Ropivacaine inhibits proliferation, migration, and invasion while inducing apoptosis of glioma cells by regulating the SNHG16/miR-424-5p axis.

BACKGROUND: Regional anesthesia has anti-proliferative and pro-apoptotic effects in various cancers. Therefore, the purpose of this study was to investigate the effects of ropivacaine on the proliferation, migration, invasion, and apoptosis of glioma cells in vitro. METHODS: Under ropivacaine stimulation conditions, proliferation, apoptosis, migration, and invasion of glioma cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazol-3-ium bromide (MTT), flow cytometry, and transwell assays, respectively. Western blot assay was employed to measure the protein expression levels in glioma cells. The expression levels of small nucleolar RNA host gene 16 (SNHG16) and miR-424-5p were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The interaction relationship between SNHG16 and miR-424-5p was predicted and confirmed using a bioinformatics database and dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. RESULTS: After treatment with ropivacaine, proliferation, migration, and invasion were repressed while apoptosis was enhanced in glioma cells in a dose-depended manner. In addition, ropivacaine impeded SNHG16 expression in glioma cells. Importantly, overexpression of SNHG16 abolished the ropivacaine-induced effects on glioma cells. Analogously, knockdown of miR-424-5p counteracted the function of ropivacaine in glioma cells. We also found that SNHG16 bound to miR-424-5p and negatively regulated miR-424-5p expression in glioma cells. The rescue experiments indicated that ropivacaine might regulate glioma progression by targeting the SNHG16/miR-424-5p axis. CONCLUSION: Our findings revealed the anti-tumor effects of ropivacaine in glioma by targeting the SNHG16/miR-424-5p axis. These data might extend the understanding of regulatory mechanisms by which ropivacaine could suppress glioma development.

Nitrogen-doped flower-like porous carbon nanostructures for fast removal of sulfamethazine from water.

The increasing concern for the toxicity of sulfamethazine (SMT) in water requires the establishment of effective water treatment processes to remove it. In this study, a novel adsorbent of nitrogen-doped flower-like porous carbon nanostructures (N-doped FPC) was proposed for the adsorption removal of SMT. The N-doped FPC possessed high surface area, good water dispersibility, and alkaline surface, endowing it with great adsorption efficiency towards SMT. The adsorption equilibrium data can be well fitted by both the Langmuir and Temkin models, and the maximum monolayer adsorption capacity of N-doped FPC was 610 mg g-1 for SMT at 298 K. The N-doped FPC exhibited fast adsorption rate for SMT and adsorption equilibrium reached within only 5 min. The pseudo-first-order model described adsorption kinetics data well and the external mass transport was the rate-limiting step. The thermodynamic parameters (ΔG, ΔH, and ΔS) showed that the adsorption of SMT onto N-doped FPC was a feasible, spontaneous, and endothermic physisorption process. After five consecutive sorption/desorption cycles, the N-doped FPC retained more than 85% adsorption capacity. This study confirmed the promising potential of N-doped FPC as high-performance adsorbents for water purification.

Determination of Quinolone Antibiotic Residues in Human Serum and Urine Using High-Performance Liquid Chromatography/Tandem Mass Spectrometry.

Quinolone antibiotic residues may pose potential threat to human health. A rapid and sensitive method was developed for the determination of quinolone residues in human serum and urine. After solid phase extraction (SPE) process, eight quinolone residues were analyzed by high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) using ciprofloxacin-d8 as the internal standard. The relative standard deviation of intra-day and inter-day precision for the eight quinolones were less than 7.52% and the accuracies ranged from 95.8% to 103% in human serum, and from 94.1% to 104% in human urine. The extraction recoveries for the eight quinolones varied from 80.2% to 113% in human serum and 83.4% to 117% in human urine. The limit of detection for the eight quinolones was 0.50-1.00 ng/mL. Quinolone antibiotic residues in human serum and urine from 12 volunteers were successfully analyzed with the validated method. The SPE-HPLC-MS/MS method was useful for accurate determination of quinolone antibiotic residues in human body.

Porous covalent organonitridic frameworks for solid-phase extraction of sulfonamide antibiotics.

Porous covalent organonitridic frameworks (PCONFs) were applied as a packing in a solid-phase extraction cartridge for rapid extraction of eight sulfonamide antibiotics from complex samples. The detection was performed by liquid chromatography-tandem mass spectrometry under the multiple reaction monitoring mode. This enabled ultrasensitive, dependable and cost-effective simultaneous analysis of sulfacetamide, sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethoxazole and sulfisoxazole. Main parameters affecting the performance of the PCONF-packed cartridge were investigated. Under optimized conditions, this method has attractive features such as wide linear ranges (2.5-1000 ng·L-1), low limits of detection (0.14-2.0 ng·L-1), and good repeatability (intra-day assay: 2.1%-5.6%; inter-day assay: 2.3%-12.9%). It was successfully applied in the analysis of sulfonamide residues in water, milk and chicken meat samples. Graphical abstract The use of a porous covalent organonitridic framework (PCONFs) as solid-phase extraction (SPE) material is described here for the first time. An ultrasensitive, dependable and cost-effective method was developed for simultaneous analysis of eight sulfonamide residues in water, milk and chicken meat samples by coupling PCONF-based SPE with liquid chromatography-tandem mass spectrometry.