Solid-phase Extraction Adsorbent Research Articles

Effectiveness of Water Hyacinth Biochar as a Potential Adsorbent in Solid-Phase Extraction Together with Liquid Chromatography-Mass Spectrometry for Determination of Pesticide Residues in Lager Beer

Effectiveness of Water Hyacinth Biochar as a Potential Adsorbent in Solid-Phase Extraction Together with Liquid Chromatography-Mass Spectrometry for Determination of Pesticide Residues in Lager Beer

UiO-66@Fe3O4 nanocomposite as an adsorbent in dispersive solid phase extraction of metformin in surface water and wastewater

Metformin, an anti-hypoglycemic medication, has been used for decades due to its efficiency and is the most consumed pharmaceutical drug worldwide. Consequently, monitoring its concentration in environmental water is important due to its suspected effect on human health and aquatic life. This study reported the extraction, preconcentration, separation and determination of metformin (MET) in waters. Dispersive solid phase extraction (dSPE) using UiO-66@Fe3O4 nanocomposite as a sorbent was used to extract and preconcentrate MET. The high-performance liquid chromatography-diode array detector (HPLC-DAD) achieved the separation and quantification of MET in the samples. Experiemental design was used to optimise influential variables in the extraction and preconcentration of MET. The linearity, limit of detection (LOD) and limit of quantification (LOQ) for MET were 0.5–100 μg L−1 (R2 = 0.9987), 0.16 μg L−1 and 0.53 μg L−1, respectively. The intraday (n = 10 same-day replicates) and interday (n = 5 consecutive days) precisions reported as relative standard deviations (RSD %) were less than 5%. The accuracy of the method expressed as percentage recovery (%R) ranged from 84 to 112%. The method was applied to extract and preconcentrate MET in wastewater and river water samples. The MET was detected in greater concentrations in wastewater than in river water samples. The validation based on specificity, trueness, linearity, precision, and application to the analysis of MET in real samples showed that the combination of dSPE and HPLC-DAD methods is applicable for MET monitoring in surface water and wastewater. Furthermore, the dSPE/HPLC-DAD method was rapid, simple and suitable for estimating the concentrations of MET in South African surface water and wastewater for the first time. Lastly, the environmental risk caused by the occurrence of MET in surface water was investigated in terms of hazard quotient (HQ). The HQ values were less than unity, suggesting a low possibility risk for the aquatic organisms.

Magnetic solid-phase extraction of tetracyclines from milk using metal-organic framework MIL-101(Cr)-NH2 functionalised hydrophilic magnetic nanoparticles

Novel metal-organic framework MIL-101(Cr)-NH2 functionalised hydrophilic polydopamine-modified Fe3O4 magnetic nanoparticles (Fe3O4@PDA@MIL-101(Cr)-NH2) were synthesised and used as magnetic solid-phase extraction (MSPE) adsorbents for extracting tetracyclines (TCs) from milk samples. The integrated Fe3O4@PDA@MIL-101(Cr)-NH2 exhibited convenient magnetic separation and exceptional multi-target binding capabilities. Furthermore, the PDA coating significantly enhanced the hydrophilicity and extraction efficiency of the material, thereby facilitating the extraction of trace TCs. Various factors affecting MSPE, such as adsorbent dosage, extraction time, pH value, and desorption conditions, were optimised. The developed MSPE method coupled with high-performance liquid chromatography demonstrated good linearity (R2 ≥ 0.9989), acceptable accuracy (82.2%–106.1%), good repeatability (intra-day precision of 0.8%–4.7% and inter-day precision of 1.1%–4.5%), low limits of detection (2.18–6.25 μg L−1), and low limits of quantification (6.54–18.75 μg L−1) in TCs detection. The approach was successfully used for the quantification of trace TCs in real milk samples.

High selectivity and anti-interference molecularly imprinted polymer based on spheroidal carbonized polymer dots for effective sulfadiazine sodium removal

Although several methods for enhancing the selectivity of molecularly imprinted polymers (MIPs) have been reported, their effects on complex substrates remain unsatisfactory. In this study, a customised 1-vinyl-3-hydroxyethylimidazolium tetrafluoroborate ionic liquid with a vinyl double bond polymerizable unit and an F-atom recognition unit was employed as a precursor carbon source to prepare unique spherical carbonised polymer dots (CPDs-F) through an incomplete carbonisation process using the one-step hydrothermal method. Then used it as a novel functional monomer, sulfadiazine sodium (SDS), as a template to synthesize the SDS-imprinted material CPDs-F@MIP in aqueous media. The results indicated that the obtained CPDs-F@MIP exhibited excellent selectivity for the template, with an imprinting factor of up to 6.39, surpassing that of the MIPs prepared with chain functional monomers 2.12–4.76 times. The selective adsorption of the template molecule, SDS (selectivity coefficient: approximately 2.615–43.149), was not significantly influenced by the coexistence of contaminants with various structural characteristics. The maximum adsorption capacity reached 61.06 mg g−1. After at least twenty applications, the adsorption capability of CPDs-F@MIP did not decrease significantly. Finally, the prepared CPDs-F@MIP were used as solid-phase extraction adsorbents in combination with high-performance liquid chromatography, and the anti-interference ability and selective adsorption performance of CPDs-F@MIP in six actual water samples were investigated. Additionally, an accurate, reliable method for detecting SDS in environmental water and poultry food was established (limit of detection of 0.2 μg L−1, and the recoveries ranged from 91.79 % to 111.32 %). Imprinting materials prepared using spherical functional monomers significantly enhance their selective recognition ability in complex media and provide new ideas for the preparation and application of novelty imprinting materials with superior performance.

Valorisation of coal gasification slag and fly ash to mesoporous activated carbon @zeolite socony mobil-5 composite for preconcentration of pharmaceuticals and their removal

Upcycling industrial solid waste, such as coal gasification slag and fly ash, to functional adsorbents with unique structures for water decontamination is of great importance to achieving Sustainable Development Goal 6.0. This study used coal gasification slag and fly ash to synthesise mesoporous activated carbon @zeolite socony mobil-5 (MAC@ZSM-5) composite. Various analytical techniques were used to investigate the surface, morphological, and structural properties of the MAC@ZSM-5 composite. The MAC@ZSM-5 composite had a relatively high specific surface and was classified as a mesoporous adsorbent. The MAC@ZSM-5 composite was used as an adsorbent in ultrasound-assisted micro solid phase extraction (UA-µSPE) for effective preconcentration and removal of aspirin (ASP), ibuprofen (IBP), and paracetamol (PCT) from water samples before determination by high-performance liquid chromatography equipped with a photodiode array detector (HPLC-DAD). The Langmuir adsorption isotherm characterised the adsorptive removal method, while the kinetics followed a pseudo-second order type. Thermodynamic studies revealed that the adsorption process was endothermic, spontaneous, and chemisorption. Additionally, the UA-µSPE/HPLC-DAD method displayed a good linear range of 0.1–1000 µg/L, with a coefficient of determination greater than 0.99. The developed method had a good performance, as shown by the relatively low limits detection (LODs: 0.017–0.064 µg/L) and quantification (LOQs: 0.057–0.21 µg/L) as well as high precision (relative standard deviation (%RSD) < 5 %). The proposed method was applied successfully for preconcentration and removal of the target analytes from real water samples. The MAC@ZSM-5 composite was reusable (up to 5 cycles) and proved a promising adsorbent for effective extraction, preconcentration, and adsorptive removal of emerging contaminants from water bodies.

Magnetic dispersive solid-phase extraction of clarithromycin and azithromycin by Fe3O4@ionic salt g-C3N4 adsorbent and HPLC-UV

In this study, Fe3O4@ionic salt g-C3N4 was synthesized as a new adsorbent for magnetic dispersive solid phase extraction (MDSPE) of two antibiotics (clarithromycin and azithromycin) in biological samples followed by HPLC-UV. The new nanocomposite was characterized by Fourier-transform infrared (FT-IR), field emission-scanning electronic microscope (FE-SEM), transmission electron microscope (TEM), nitrogen adsorption–desorption analysis, X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Box-Behnken design (BBD) and response surface methodology (RSM) were used for the optimization and design of experiments. The method had a suitable linear range (1–300 µg/L), a high coefficient of determination (R2; 0.9988 and 0.9993), and a low detection limit (0.33 and 0.42 µg/L) for clarithromycin and azithromycin, respectively. The applicability of the method was evaluated by estimating the recovery of analytes from urine and blood serum samples. Recovery of more than 90.0 % and RSDs of less than 5.2 % show the acceptable accuracy and precision of the proposed method.

Development of a NiFe2O4 covalent organic framework based magnetic solid-phase extraction approach for specific capture of quinolones in animal innards prior to UHPLC–Q–Orbitrap HRMS detection

This study aimed to present a selective and effective method for analyzing quinolones (QNs) in food matrix. Herein, a NiFe2O4-based magnetic sodium disulfonate covalent organic framework (NiFe2O4/COF) was prepared using a simple solvent-free grinding method, and was adopted as a selective adsorbent for magnetic solid phase extraction of QNs. Coupled with UHPLC–Q–Orbitrap HRMS, an efficient method for simultaneous detection of 18 kinds of QNs was established. The method exhibited good linearity (0.01–100 ng g−1), high sensitivity (LODs ranging from 0.0011 to 0.0652 ng g−1) and precision (RSDs below 9.5%). Successful extraction of QNs from liver and kidney samples was achieved with satisfactory recoveries ranging from 82.2% to 108.4%. The abundant sulfonate functional groups on NiFe2O4/COF facilitated strong affinity to QNs through electrostatic and hydrogen bonding interactions. The proposed method provides a new idea for the extraction of contaminants with target selectivity.

Nitrogen-doped magnetic porous carbon nanospheres derived from dual templates-induced mesoporous polydopamine coated Fe3O4 for efficient extraction and sensitive determination of volatile nitrosamines by gas chromatography-mass spectroscopy

N-nitrosamines (NAs) are highly carcinogenic compounds commonly found in food, beverages, and consumer products. Due to their wide polarity range, it is challenging to find a suitable carbon adsorbent that can simultaneously adsorb and enrich both polar and nonpolar NAs with good recovery. In this study, nitrogen-doped magnetic mesoporous carbon nanospheres (M-MCN) were prepared and employed as an adsorbent for magnetic solid-phase extraction (MSPE) to extract and concentrate four NAs. The introduction of nitrogen functional groups enhanced the hydrophilicity of the carbon material, allowing M-MCN to achieve a balance between hydrophilicity and hydrophobicity, resulting in good recovery for both polar and nonpolar NAs. A method combining MSPE with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of NAs in processed meat and alcoholic beverages. The method exhibited a good linear range (1-100 ng g-1, r2 > 0.9967) and trace-level detection (0.53-6.6 ng g-1). The recovery rates for the four NAs ranged between 85.7-110.7%, with intra-day precision expressed as relative standard deviation (RSD) between 4.1-10.7%, and inter-day precision between 4.8-12.9%. The results demonstrated not only good accuracy and precision but also provided a new adsorbent for the enrichment of trace-level NAs in processed meat and alcoholic beverage samples.

The magnetic layered double hydroxide/zeolitic imidazolate framework-8 nanocomposite coupled with HPLC-MS/MS for the detection of heterocyclic aromatic amines in thermally processed meat

In this research, a novel magnetic nanocomposite (Fe3O4@Zn/Al-LABSA-LDH/ZIF-8) was synthesized using Fe3O4 as the magnetic core, layered double hydroxide (LDH) with linear alkylbenzene sulfonic acid (LABSA) intercalation and zeolitic imidazolate framework-8 (ZIF-8) as the shell. Benefiting from the intercalation of LABSA into LDH combined with ZIF-8, the multiple interactions, including π-π stacking, hydrogen bonding, and electrostatic interactions, conferred high selectivity and good extraction capability to the material towards heterocyclic aromatic amines (HAAs). Fe3O4@Zn/Al-LABSA-LDH@ZIF-8 was used as an adsorbent for magnetic solid-phase extraction (MSPE) to enrich HAAs in thermally processed meat samples, followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) detection. The method exhibited a low detection limit (0.021–0.221 ng/g), good linearity (R2 ≥ 0.9999), high precision (RSD < 7.2 %), and satisfactory sample recovery (89.7 % -107.5 %). This research provides a promising approach for developing novel adsorbents in sample preparation and improving analytical performance.

Covalent organic frameworks as dispersive solid-phase extraction adsorbents for β-lactam detection in aquatic environments

Currently, antibiotic residues in the environment pose a serious public health risk; therefore, new sensitive approaches for detecting the presence of antibiotics are urgently needed. Ionic-type covalent organic frameworks (TAPB-(TFIT)+Cl−-COFs) were designed and prepared in this work, and these imine-linked COFs were characterized by several techniques, proving of porous structure and rich of nitrogen. The materials were applied to the extraction of β-lactams from aqueous samples, and the important parameters of the adsorption–desorption conditions were optimized. A dispersive solid-phase extraction method coupled with ultrahigh-performance liquid chromatography-tandem mass spectrometry (TAPB-(TFIT)+Cl−-COFs-d-SPE-UPLC-MS/MS) was proposed and utilized to determine the levels of 11 antibiotics in the β-lactams in the extracted samples. Good linearity (1.0–200.0 μg·L−1, r > 0.9999) was achieved together with limits of detection and quantification of 0.01–0.92 μg·L−1 and 0.05–2.78 μg·L−1, respectively; recoveries ranged from 75.57 to 114.20 %, conferring relative standard deviations < 8.99 % and negligible matrix effects (84.88–109.40 %). The synthesized TAPB-(TFIT)+Cl−-COFs were demonstrated to have good reusability and high stability. Furthermore, the proposed method was clearly shown to be sensitive and separable for the reliable simultaneous detection of 11 β-lactam residues in aquatic environments.

Synthesis of weak cation exchange/C18 bifunctional magnetic polymers for pretreatment and determination of glufosinate and its two metabolites in plasma samples

This study focuses on the purification and detection of glufosinate (GLUF) and its metabolites N-acetyl GLUF and MPP in plasma samples. A Dikma Polyamino HILIC column was used for the effective retention and separation of GLUF and its metabolites, and the innovative addition of a low concentration of ammonium fluoride solution to the mobile phase effectively improved the detection sensitivity of the target analytes. Monodisperse core-shell weak cation exchange (WCX)/C18 bifunctional magnetic polymer composites (Fe3O4@WCX/C18) were prepared in a controllable manner, and their morphology and composition were fully characterized. The Fe3O4@WCX/C18 microspheres were used as a magnetic solid-phase extraction (MSPE) adsorbent for the sample purification and detection of GLUF and its metabolites in plasma samples combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The purification conditions of Fe3O4@WCX/C18 microspheres for GLUF and its metabolites in spiked plasma samples were optimized to achieve the best MSPE efficiency. The purification mechanisms of the target analytes in plasma samples include electrostatic attraction and hydrophobic interactions. Furthermore, the effect of the molar ratio of the two functional monomers 4-VBA and 1-octadecene in the adsorbent was optimized and it shows that the bifunctional components WCX/C18 have a synergistic effect on the determination of GLUF and its metabolites in plasma samples. In addition, the present study compared the purification performance of the Fe3O4@WCX/C18 microsphere-based MSPE method with that of the commercial Oasis WCX SPE method, and the results showed that the Fe3O4@WCX/C18 microsphere-based MSPE method established in this work had a stronger ability to remove matrix interferences. Under optimal purification conditions, the recoveries of GLUF and its metabolites in plasma were 87.6–111 % with relative standard deviations (RSDs) ranging from 0.2 % to 4.8 %. The limits of detection (LODs, S/N≥3) and limits of quantification (LOQs, S/N≥10) were 0.10–0.18 μg/L and 0.30–0.54 μg/L, respectively. The MSPE-LC-MS/MS method developed in this study is fast, simple, accurate and sensitive and can be used to confirm GLUF intoxication based not only on the detection of the GLUF prototype but also on the detection of its two metabolites.

Natural kapok fiber as a green and efficient adsorbent for in-syringe solid-phase extraction in the determination of antidepressants in biofluids

Effective antidepressant monitoring is crucial for safe treatment, with liquid chromatography being the primary detection method. Due to the complexity of biofluids, meticulous sample preparation is vital to remove interferences and concentrate analytes. In this study, a novel solid-phase extraction method utilizing unprocessed kapok fiber (KF) as an eco-friendly and efficient sorbent, ingeniously incorporated within an in-syringe device for the extraction of antidepressants from biofluids was introduced. The extraction process displayed several advantages, including simplicity and rapidity (less than 3 min with minimal manual intervention), as well as the potential for automation, which represents significant advancements in sample preparation techniques. The method demonstrated excellent analytical performance when coupled with high-performance liquid chromatography-ultraviolet detection, achieving good linearity (R2 ≥ 0.991), excellent relative recovery (92.6–107.5 %), high precision in intraday and interday analyses (RSDs within 0.8–6.0 % and 1.2–7.9 %, respectively), and good sensitivity with limits of quantification between 5–10 ng/mL. Notably, given the use of a renewable and biodegradable material with KF, and a low-toxicity desorption solvent with ethanol, the developed method stands out for its environmental sustainability, aligning with green analytical chemistry principles. Its application to real biological samples validates its efficacy as a rapid and reliable tool for clinical and forensic monitoring of antidepressants. Moreover, the low cost of this method facilitated by the economical nature of KF and the reusability of syringes further enhances its practicability. This study presents a unique approach by employing natural and renewable KF as adsorbents, thereby eliminating the need for complex material synthesis and making a pioneering contribution to the field of analytical chemistry for drug analysis in complex matrices.

One-step grafting of phenyl functionalized magnetic mesoporous nanocomposites for magnetic dispersive solid-phase extraction and determination of triazole fungicide residues in strawberry fruits

In this work, phenyl-SBA-15@Fe3O4 organic phenyl functional magnetic mesoporous materials were synthesized as adsorbent for magnetic dispersive solid phase extraction (M−DSPE) sample pretreatment. Seven triazole fungicides were simultaneously analyzed by high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). The extraction recovery was 82.7 %-88.6 %, and the concentration factor was 10.6–30.8. Under the optimized experimental conditions, the regression equations of seven triazole fungicides showed a good linear relationship, the coefficient of determination r2 was 0.9993–0.9999, and the detection limit was 0.19 ∼ 1.75 μg·L-1. Six strawberry samples were randomly purchased from different places in the market, and flesh,cortex, sepal, and pulp were detected separately. The results showed that flutriafol, triadimenol and difenoconazole were detected, of which flutriafol was detected from all of them and most of them exceeded the national standard. The extraction pretreatment technology is fast and efficient, which can meet the requirements of simultaneous analysis of triazole fungicide residues in strawberries.

Determination of sulfonamide antibiotics by magnetic porous carbon solid-phase extraction coupled with capillary electrophoresis

Sulfonamide antibiotics (SAs) have been widely used as antibacterial drugs for the prevention and treatment of livestock and poultry diseases, but they seriously threaten human health because they can accumulate in humans. Therefore, it is highly important to develop methods for monitoring sulfonamide residues in aquaculture and food. In this research, based on the generation of porous carbon (PC) by the pyrolysis of sodium citrate, magnetic porous carbon (PC@Fe3O4) was synthesized by a solvothermal method and used as an adsorbent for the magnetic solid-phase extraction of SAs. The effects of the proportion of PC in PC@Fe3O4, adsorbent dosage, adsorption time, eluent type, extraction pH, salt concentration and eluent dosage on the extraction efficiency were systematically studied. The adsorption performance and behavior of PC@Fe3O4 on SAs were evaluated using adsorption kinetics and adsorption isotherms, and the adsorption mechanism was preliminarily discussed. Under optimal conditions, combined with capillary electrophoresis diode array detection, a sensitive detection method for SAs was developed. The proposed method can be used for the determination of six SAs in fishpond water and milk samples, with a linear range of 0.5–200 ng mL−1, detection limits of 0.24–0.34 ng mL−1, and spiked recoveries of 85.9–109.0 %.

Magnetic iron-based metal organic framework as an adsorbent for magnetic dispersive solid-phase extraction of pyrene and phenanthrene in water samples

ABSTRACT A dispersive magnetic solid-phase extraction by means of core-shell iron-based metal-organic framework (Fe3O4- SiO2/EN@MIL-101(Fe)) nanospheres coupled with high-performance liquid chromatographic was developed for the determination of pyrene (Pyr) and phenanthrene (Phe) in water samples. Key parameters such as sorbent amount, sample volume, pH, extraction time, type and volume of elution, and desorption time were optimised by response surface methodology (RSM). Under the optimised conditions (sample volume: 5 mL, extraction time: 3 min, eluent: 3 mL acetonitrile: propanol, and desorption time: 3 min), the developed method showed a low detection and quantification limits (0.015 and 0.040 ng mL−1, respectively), good precision (< 9.8% RSD), wide linear range (0.06 - 10,000 ng mL−1, R2 > 0.99), high enrichment factors (49–57), good matrix effect (> 93.2%), high reusability (25 times), short extraction and desorption time (3 and 3 min, respectively), and high extraction recovery (96.5%). The established method was able to recover the Pyr and Phe from spiked real water samples with an extraction efficiency of 95.71% and 96.32%, respectively (RSD ≤ 9.52%).

Effective enrichment and separation of three flavonoids from Ohwia caudata (Thunberg) H. Ohashi using magnetic layered double hydroxide/ZIF-8 composites and pCEC

In this study, Fe3O4@ZnCr–layered double hydroxide/zeolitic imidazolate frameworks-8 (MLDH/ZIF-8) magnetically functionalized composites were synthesized by co-precipitation and in situ growth based on the advantages of LDHs and ZIF-8 using Fe3O4 nanoparticles as a magnetic substrate to obtain adsorbents with excellent performance. Moreover, the composite was used for the efficient enrichment of flavonoids in Chinese herbal medicines. The internal structures and surface properties were characterized by SEM, Fourier transform infrared spectroscopy, X-ray diffraction and so on. MLDH/ZIF-8 exhibited a large specific surface area and good paramagnetic properties. The MLDH/ZIF-8 magnetic composite was used as a magnetic solid-phase extraction (MSPE) adsorbent, and a MLDH/ZIF-8 MSPE–pressurized capillary electrochromatography coupling method was developed for the separation and detection of flavonoids (luteolin, kaempferol and apigenin) in a sample of the Chinese herb Ohwia caudata (Thunberg) H. Ohashi. The relevant parameters affecting the extraction efficiency were optimized to determine the ideal conditions for MSPE. 5 mg of adsorbent in sample solution at pH 6, vortex extraction for 5 min, elution with 1.5 mL of ethyl acetate for 15 min. The method showed good linearity in the concentration range of 3–50 μg mL−1 with correlation coefficients of 0.9934–0.9981, and displayed a relatively LODs of 0.07–0.09 μg mL−1. The spiked recoveries of all analytes ranged from 84.5% to 122.0% with RSDs (n=3) between 4.5% and 7.7%. This method is straightforward and efficient, with promising potential in the separation and analysis of active ingredients in various Chinese herbal medicines.

Optimization of volatile organic compounds sampling from dairy cow exhaled breath using polymer-based solid-phase extraction cartridges for gas chromatographic analysis

We explored appropriate technical setups for the detection of volatile organic compounds (VOCs) from exhaled cow breath by comparing six different polymer-based solid-phase extraction (SPE) cartridges currently on the market for gas chromatography/mass spectrometry (GC-MS) screening. Exhaled breath was sampled at a single timepoint from five lactating dairy cows using six different SPE cartridges (Bond Elut ENV (ENV); Chromabond HRX (HRX); Chromabond HRP (HRP); Chromabond HLB (HLB); Chromabond HR-XCW (XCW) and Chromabond HR-XAW (XAW)). The trapped VOCs were analyzed by dynamic headspace vacuum in-tube extraction GC-MS (DHS-V-ITEX-GC-MS). Depending on the SPE cartridge, we detected 1174–1312 VOCs per cartridge. Most VOCs were alkenes, alkanes, esters, ketones, alcohols, aldehydes, amines, nitriles, ethers, amides, carboxylic acids, alkynes, azoles, terpenes, pyridines, or sulfur-containing compounds. The six SPE cartridges differed in their specificity for the chemical compounds, with the XAW cartridge showing the best specificity for ketones. The greatest differences between the tested SPE cartridges appeared in the detection of specific VOCs. In total, 176 different VOCs were detected with a match factor >80%. The greatest number of specific VOCs was captured by XAW (149), followed by ENV (118), HLB (117), HRP (115), HRX (114), and XCW (114). We conclude that the tested SPE cartridges are suitable for VOC sampling from exhaled cow breath, but the SPE cartridge choice enormously affects the detected chemical groups and the number of detected VOCs. Therefore, an appropriate SPE adsorbent cartridge should be selected according to our proposed inclusion criteria. For targeted metabolomics approaches, the SPE cartridge choice depends on the VOCs or chemical compound groups of interest based on our provided VOC list. For untargeted approaches without information on the animals’ metabolic condition, we suggest using multi-sorbent SPE cartridges or multiple cartridges per animal.

Rapid and selective detection of tetracyclic antibiotics in environmental water using Cu2+-doped hydrophilic imprinted melamine resin

Antibiotic contamination in environmental waters often occurs at low residue levels, necessitating pre-analysis concentration. To address this, we synthesized a hydrophilic molecularly imprinted resin (MIR) using melamine, urea, and formaldehyde as monomers, with oxytetracycline as the template molecule. Enhanced adsorption efficiency was achieved by doping the resin with Cu2+, which forms stable complexes with oxytetracycline. This Cu2+-doped MIR (Cu-MIR) was employed as a selective adsorbent in solid-phase extraction (SPE) to enrich four tetracycline antibiotics (TCs) from aqueous solutions. The optimized parameters for Cu-MIR in environmental water sample analysis resulted in linear detection ranges from 0.20 to 40 ng/mL, recoveries between 80.2 % to 102.4 %, relative standard deviations ≤ 9.0 %, a detection limit of 0.1 ng/mL, and the enrichment factors were between 4.79–5.13, as determined by HPLC-MS. Given its diverse adsorption mechanisms and specificity, Cu-MIR shows promise for practical applications in real-world sample analysis.

Spherical fluorinated covalent organic polymer for highly efficient and selective extraction of fipronil and its metabolites in soil

Covalent organic polymers (COPs) have garnered considerable attention as promising adsorbents of online solid phase extraction (online SPE). Morphology modulation provides an appealing solution to enhance adsorption efficiency and reduce back-pressure in the absorbent. However, the synthesis of COPs with regular geometric shapes and specific adsorption selectivity remains challenging. In this study, a uniform spherical fluorinated COP (F-sCOP, average diameter: 2.14 μm) was successfully synthesized by Schiff base reaction of 1,3,5-triformylphoroglucinol (TP) and 2,2’-bis(trifluoromethyl)benzidine (TFMB). The F-sCOP had a large surface area (BET: 346.2 m2 g−1), remarkable enrichment capacity (enrichment factors: 186–782), high selectivity toward fipronil and its metabolites (adsorption efficiency >93.1%), and admirable service life (>60 times). Based on the adsorbent, a novel μ-matrix cartridge extraction-online-μ-solid phase extraction-high performance liquid chromatography-mass spectrometry (μ-MCE-online-μ-SPE-HPLC-MS) method was constructed and used to track trace fipronil and its metabolites in soil. The proposed method exhibited a wide linear range (0.05–1000 ng g−1), low quantitation limits (LOQs: 0.0027–0.011 ng g−1), high recoveries (90.1–119.6%) and good repeatability (RSD ≤10.5%, n = 3) for fipronil analysis. This study paves the way for pesticide analysis in soil risk assessment.

Magnetic Poly(Amidoamine) Dendrimer for the Dispersive Solid Phase Extraction of Nitrophenols from Environmental Water Samples.

A fast and simple dispersive solid phase extraction method is described for nitrophenols determination in water samples by using gas chromatography-nitrogen phosphorous detector. Firstly, the Poly(amidoamine) grafted Fe3O4 magnetic nanoparticles were synthesized in different generations by successive addition of butyl acrylate and ethylenediamine. After characterization, the prepared dendrimer was utilized as an adsorbent for magnetic solid phase extraction of 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol to benefit large number of surface amine interaction sites. The effects of the different parameters influencing the sample preparation efficiency were investigated. The proposed method showed linearity in the ranges of 0.04-700 and 0.05-700µg/dm3 for nitrophenols. The obtained limits of detection and quantification under optimized conditions were 0.01-0.02 and 0.04-0.05µg/dm3, respectively. The relative standard deviations (n = 5) were less than 3.8% (at 10µg/dm3). Moreover, the calculated enrichment factors were above 200. In addition, the relative recoveries for a spiked river water sample were satisfactory.