Multifunctional polymeric microspheres were prepared using hyper-cross-linking chemistry combined with surface-initiated atom transfer radical polymerization. The synthesized microspheres exhibited good water dispersibility, a high surface area, and pH/thermo dual-responsiveness. Fluoroquinolones (FQs), which contains a hydrophilic piperazine ring and hydrophobic fluorine atoms, were used as target analytes to assess the performance of the microspheres as a sorbent for dispersive solid-phase extraction (d-SPE). The d-SPE experimental parameters, including extraction time, amount of microspheres, extraction temperature, and sample solution pH, as well as the desorption conditions, were systematically studied. Coupled with LCMS/MS, an analytical method for analysis of trace-level FQs in water samples was developed and validated. Under optimal conditions, linearity with correlation coefficients (r) of >0.99 was achieved in the concentration range of 0.02–10 μg L−1. The limits of detection and quantification for the selected FQs were 5.0–6.7 and 12–20 ng L−1, respectively. High recovery values (93.1%–97.2%), a high enrichment factor (˜180), and good precision (RSD < 8%, n = 6) were obtained for FQ determination in spiked purified water samples. It was proposed that hydrophilic–hydrophobic transition induced by stretching and shrinking of polymer chains under different pH and temperature conditions offered good control of the surface wettability and altered the extraction behavior. The developed method was validated and was successfully applied to the analysis of FQs in environmental water samples, meat and milk samples. These results demonstrated that the water-dispersible polymeric microspheres have good potential for use in separation and extraction techniques.

In this study, ultralayered Co₃O₄ adsorbent was synthesized and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface area of the solid material was found to be 75.5m²g⁻¹ by BET method. The ultralayered Co₃O₄ was used for the first time as an effective adsorbent for the preconcentration of the Pb(II) ions in various samples prior to flame atomic absorption detection. Analytical parameters affecting the solid phase extraction of Pb(II) such as pH, adsorption and elution contact time, eluent volume and concentration, sample volume and common matrix ions were investigated. The recovery values for Pb(II) were found to be ≥92% even in the presence of 75,000mgL⁻¹ Na(I), 75,000mgL⁻¹ K(I), and 75,000mgL⁻¹ Ca(II) ions. 10s vortexing time was enough for both adsorption and elution contact times. The elution was easily made with 2mL of 2.0molL⁻¹ HNO₃. The reusability (170 cycles) and adsorption capacity (35.5mgg⁻¹) of ultralayered Co₃O₄ were excellent. The preconcentration factor of the method and detection limit were found to be 175 and 0.72µgL⁻¹, respectively. The described method was validated with certified reference material (RM 8704 Buffalo River Sediment, BCR-482 Licken and SPS-WW1 Batch 111-Wastewater) and spiked real samples. It was also applied for the preconcentration of Pb(II) ions in various water (well water, mineral water, waste water and sea water), food (cauliflower and barley), street sediment and tobacco samples.

To develop an accurate and precise method for separation and pre-concentration of Hg(II), a novel thionin functionalised core shell structure magnetic material has been prepared and characterised. The extraction ability of the material was evaluated by magnetic solid-phase extraction coupled with inductively coupled plasma mass spectrometry determination of Hg(II) in food and water samples. Combining the advantages of magnetic separation with selective extraction of thionin towards Hg(II), the material exhibits enhanced enrich selectivity and efficiency for Hg(II). The experimental parameters influencing Hg(II) extraction efficiency, including pH of the aqueous solution, the dosage of the adsorbent, extraction time and sample volume, were systematically investigated. Under the optimised conditions, concentration of Hg(II) at 1.0 μg L⁻¹ can be successfully enriched by the material without the interference of the common co-existing ions. The enrichment factor and adsorption capacity were 250 and 75.2 mg g⁻¹, and precise of the method was confirmed by analysing the spiked food, water samples and standard water reference samples with the recoveries of 92.5–101.8%.

A magnetic covalent organic framework nanocomposite (Fe₃O₄@COF(Tp-NDA)) was synthesized via a solvothermal method, used as a magnetic adsorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) from lake water, tea, coffee, and fried chicken, and detected using a high performance liquid chromatography-ultraviolet detector. The synthesized magnetic adsorbent was characterized via transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption–desorption isotherm analysis and vibrating sample magnetometry. Parameters that affected the extraction conditions and desorption conditions were optimized. Adsorption equilibrium could be attained within 3 min. The prepared magnetic material could be reused 10 times. The limits of detection and quantification were 0.05–0.25 μg L⁻¹ and 0.17–0.83 μg L⁻¹, respectively. The recovery was 74.6–101.8% with a relative standard deviation of below 4.2%. The method was successfully used to detect PAHs in various samples.

A simple and rapid vortex-assisted magnetic solid phase extraction (VA-MSPE) method for the separation and preconcentration of ziram (zinc dimethyldithiocarbamate), subsequent detection of the zinc in complex structure of ziram by flame atomic absorption spectrometry (AAS) has been developed. The ziram content was calculated by using stoichiometric relationship between the zinc and ziram. Magnetic carboxylated nanodiamonds (MCNDs) as solid-phase extraction adsorbent was prepared and characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry and scanning electron microscopy (SEM). These magnetic carboxylated nanodiamonds carrying the ziram could be easily separated from the aqueous solution by applying an external magnetic field; no filtration or centrifugation was necessary. Some important factors influencing the extraction efficiency of ziram such as pH of sample solution, amount of adsorbent, type and volume of eluent, extraction and desorption time and sample volume were studied and optimized. The total extraction and detection time was lower than 10min The preconcentration factor (PF), the precision (RSD, n=7), the limit of detection (LOD) and limit of quantification (LOQ) were 160, 7.0%, 5.3µgL−1 and 17.5µgL−1, respectively. The interference of various ions has been examined and the method has been applied for the determination of ziram in various waters, foodstuffs samples and synthetic mixtures.

A new solid-phase extraction sorbent was used for the separation/preconcentration of Ni(II) ions prior to their determination by flame atomic absorption spectrometry. It was prepared by immobilization of dithiooxamide on magnetic nanoparticles (MNPs) of magnetite (Fe3O4) coated with cationic surfactant sodium dodecyl sulfate. The properties of sorbent and MNPs were characterized by scanning electron microscope and transmission electron microscope. Some parameters affecting extraction, such as pH, adsorbent dosage, and eluent concentration and volume) were optimized. The calibration graph was linear in the range 30–5000 µg.L⁻¹ with a limit of determination of 3.9 µg.L⁻¹. The relative standard deviation for Ni ions was 1.3%. The method was applied to the determination of trace amounts of Ni(II) ions in water and food samples.

Fabrication of novel coatings continues to be an area of great interest and significance in the development and application of stir bar sorptive extraction (SBSE). In this work, a carboxyl-enriched microporous organic network (MON-2COOH) coated stir bar was designed and fabricated as a novel adsorbent for efficient extraction of four phenylurea herbicides (PUHs) before their determination by high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA). The MON-2COOH was represented as an effective adsorbent for PUHs due to its large surface area, rigid porous structure, aromatic pore walls and the desired hydrogen bonding sites of introduced carboxyl groups. Variables affecting the SBSE of target analytes were optimized in detail. Under the optimal extraction conditions, favorable correlation coefficients (R² > 0.996) in the linear range 0.10–250 μg L⁻¹, low limits of detection (LODs, S/N = 3) of 0.025–0.070 μg L⁻¹ and good enrichment factors (46–49) were obtained. Besides, the proposed SBSE-HPLC-PDA method was successfully applied to determine trace PUHs in food and environmental water samples with recoveries in the range of 80.0–104.8% and the precisions (relative standard deviations, RSDs) lower than 9.9% (n = 3). This work revealed the potential of MONs in SBSE of trace contaminants from environmental samples.

A molybdenum disulfide(MoS2)-based core-shell magnetic nanocomposite (Fe₃O₄@MoS₂) was synthesized by the stepwise hydrothermal method. Two-dimension ultrathin MoS₂ sheets with a thickness of approximately 20 nm were grown in situ on the surface of Fe₃O₄ (∼200 nm). They were employed as an adsorbent for the magnetic solid-phase extraction (MSPE) of sulfonamide antibiotics (SAs) from water samples. High-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was used for SA quantitation. Extraction parameters, including the pH effect, amount of Fe₃O₄@MoS₂, extraction time, temperature, and desorption conditions, were systematically investigated. The electrostatic interaction between the positively charged SAs and negatively charged MoS₂ nanoparticles in the optimal extraction conditions enhanced the adsorption of SAs on the sorbent surface. Under chosen conditions, the proposed strategy achieved wide linear range of 1.0–1000 ng·L⁻¹ SAs, low limits of detection (LOD, 0.20–1.15 ng·L⁻¹, S/N = 3:1), good trueness (recoveries between 85.50–111.5%), satisfactory repeatability and reproducibility (relative standard deviation, <10%, n = 5), and excellent recoveries between 80.20% and 108.6% for SAs determination in spiked waste water samples. The proposed strategy was validated and successfully applied for the analysis of water, milk, pork meat and fish meat. The nanocomposites, which have the combined advantages of magnetic separation and high adsorption affinity toward SAs, are a promising sorbent for antibiotics extraction from real samples.

In the present work, titanium dioxide nanowires (TNWs) were synthesised via hydrothermal method. Insertion of ZnFe ₂O ₄ nanoparticles to the surface of TNWs was done by sol gel combustion synthesis of the nanoparticles in the presence of the nanowires. The surface of prepared magnetic TNWs was modified by p -phenylendiamine and then it was used in preconcentration of Cu ²⁺ ion prior to their determination by flame atomic absorption spectroscopy. The sorbent was characterised by Fourier transform infrared spectra, EDX, FE-SEM and VSM techniques. We investigated and optimised various parameters influencing the preconcentration efficiency, such as the media pH, adsorbent quantity, contact time, sample volume and elution conditions. Under optimum conditions, the analytical performance of the method was evaluated. The calibration curve was found to be linear from 10.0 to 150 μg L ⁻¹ (R ² = 0.996). Calculated limit of detection was 0.43 μg L ⁻¹ (n = 5). The estimated relative standard deviation was 2.50% (n = 5). Moreover, the maximum adsorption capacity of the sorbent was 51.5 mg g ⁻¹ and preconcentration factor was 125. Capability of developed method was proved by applying it for preconcentration of Cu ²⁺ ion from food and water samples.

In this paper, a new mesoporous hybrid material was fabricated by anchoring 2-mercaptobenzaldehyde (2MB) onto the surface of SBA-15. The adsorbent (2MB-SBA-15) was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption–desorption isotherm measurements and thermogravimetric analysis (TGA) and applied as a sorbent in the preconcentration of Cd(ii) in water samples and food samples. The effect of various analytical parameters such as pH, dose of sorbent, amount of eluent, sample flow rate and interfering ions was investigated. The preconcentration capacity of the prepared material under optimized conditions for Cd(ii) was 0.94 ± 0.01 mmol g⁻¹. The Cd collected onto the sorbent was eluted out with 10 mL of 1 M HNO₃ and determined by AAS. The LOD, LOQ and preconcentration factor of the present method were found to be 6.93 × 10⁻⁶, 1.21 × 10⁻⁵ mM and 100, respectively. The relative standard deviation for four preconcentration experiments was found to be ≤5%.