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This study investigated the adsorption of methyl orange (MO) from aqueous solutions using a novel MnFe₂O₄/GO nanocomposite coated with cetyltrimethylammonium bromide (CTAB). The dual-layer surfactant modification facilitates both electrostatic and lipophilic interactions. This enhancement significantly improves dye removal efficiency. The adsorption process was monitored using spectrophotometry at 464 nm, with various characterization techniques confirming the structural and magnetic properties of the nanocomposite. The optimized parameters for maximum adsorption include a 2-minute ultrasonic dispersion, pH 6.8, and a surfactant-to-adsorbent ratio of 1, achieving a maximum adsorption capacity of 285.7 mg/g. The kinetic data followed a pseudo-second-order model, whereas the adsorption isotherm aligned with the Freundlich model, indicating multilayer adsorption. Thermodynamic analysis revealed the spontaneous and exothermic nature of the process. Additionally, the magnetic properties of the nanocomposite enabled efficient separation and reusability over three cycles without significant loss of performance. This study demonstrates the potential of MnFe₂O₄/GO coated with CTAB for rapid, efficient, and reusable removal of anionic dyes from wastewater through a combined mechanism of electrostatic and hydrophobic interactions.

Fully atomistic molecular-dynamics (MD) simulations of perfluoroalkylalkane molecules at the surface of water show the spontaneous formation of aggregates whose size and topography closely resemble the experimentally observed hemimicelles for this system. Furthermore, the grazing incidence X-ray diffraction (GIXD) pattern calculated from the simulation trajectories reproduces the experimental GIXD spectra previously obtained, fully validating the MD simulation results. The detailed analysis of the internal structure of the aggregates obtained by the MD simulations supports a definite rational explanation for the spontaneous formation, stability, size, and shape of perfluoroalkylalkane hemimicelles at the surface of water.

Nowadays, the abuse of synthetic cannabinoids has aroused the world’s great attention. However, the determination of synthetic cannabinoids in wastewater faces the bottleneck of complex species and very low content. Therefore, this work integrated GO-Fe 3 O 4 with an ionic liquid (ILs-GO-Fe 3 O 4 ) to create a mixed hemimicelles magnetic solid-phase extraction (MHMSPE) system for the detection of synthetic cannabinoids (SCs) in wastewater samples using ultrahigh-performance liquid chromatography—tandem mass spectrometry (UHPLC-MS/MS). Because of the multiple interaction sites of mixed hemimicelles’ magnetic solid-phase extraction materials, multi-structural synthetic cannabinoids can be enriched simultaneously. Under the optimized conditions, the limits of quantitation (LOQ) of the method were as low as 10–50 pg/L, lower than other methods. The average recoveries of 18 analytes were in the range 71.23–96.08% with relative standard deviations (RSD) lower than 15% ( n  = 6). To our knowledge, this is the first development of magnetic solid-phase extraction for large-volume samples pretreatment (1 L) and ultra-high sensitive detection of synthetic cannabinoids (10 pg/L), due to the high enrichment factor (10,000-fold). The extraction process was convenient, accurate, and rapid, and offers significant potential for ultra-high sensitivity detection in large-volume samples, providing a valuable tool for simultaneous broad-spectrum extraction and drug abuse monitoring. Graphical abstract

Regarding the increasing trend of methamphetamine consumption in society, identifying and measuring low levels of methamphetamine in biological matrices is of great importance for clinical and forensic laboratories. Coated ionic liquid silica nanoparticles (CILSNPs) are appropriate adsorbent candidates to extract methamphetamine with high selectivity and sensitivity from complex urine matrix using the mixed hemimicelle dispersive solid-phase extraction (MHMDSPE) method. After successful characterization of synthesized CILSNPs by various techniques such as FTIR, XRD, SEM, and Zeta potential, the one-factor-at-a-time (OFAT) method was performed to optimize effective extraction parameters. HPLC-UV method was used to detect and quantify methamphetamines. The optimized extraction parameters were as follows: 400 µL of methanol, 10 min of extraction, 5 min of desorption time, stirring rate of 2,000 rpm, urine pH of 10, 40 mg of adsorbent, and 10 mL of urine volume. The calibration curve was plotted in the 50-2000 ng/mL concentration range, and the method was validated. The method’s limit of detection (LOD) was calculated as 9 ng/mL. Analysis of addicted subjects for the proposed method proves that the method could be used in clinical and analytical laboratories to detect methamphetamine efficiently.

One of the considerable and disputable areas in analytical chemistry is a single-step simultaneous extraction of acidic and basic pollutants. In this research, a simple and fast coextraction of acidic and basic pollutants (with different polarities) with the aid of magnetic dispersive micro-solid phase extraction based on mixed hemimicelles assembly was introduced for the first time. Cetyltrimethylammonium bromide (CTAB)-coated Fe₃O₄ nanoparticles as an efficient sorbent was successfully applied to adsorb 4-nitrophenol and 4-chlorophenol as two acidic and chlorinated aromatic amines as basic model compounds. Using a central composite design methodology combined with desirability function approach, the optimal experimental conditions were evaluated. The opted conditions were pH = 10; concentration of CTAB = 0.86 mmol L⁻¹; sorbent amount = 55.5 mg; sorption time = 11.0 min; no salt addition to the sample, type, and volume of the eluent = 120 μL methanol containing 5 % acetic acid and 0.01 mol L⁻¹ HCl; and elution time = 1.0 min. Under the optimum conditions, detection limits and linear dynamic ranges were achieved in the range of 0.05–0.1 and 0.25–500 μg L⁻¹, respectively. The percent of extraction recoveries and relative standard deviations (n = 5) were in the range of 71.4–98.0 and 4.5–6.5, respectively. The performance of the optimized method was certified by coextraction of other acidic and basic compounds. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of the target analytes in various water samples, and satisfactory results were obtained.

We report on a method for the extraction of organophosphorus pesticides (OPPs) from water samples using mixed hemimicelles and magnetic titanium dioxide nanoparticles (Fe 3 O 4 @TiO 2 ) modified by cetyltrimethylammonium. Fe 3 O 4 @TiO 2 nanoparticles were synthesized by a hydrothermal process and then characterized by scanning electron microscopy and Fourier transform IR spectrometry. The effects of the quantity of surfactant, extraction time, desorption solvent, pH value, extraction volume and reuse of the sorbent were optimized with respect to the extraction of OPPs including chlorpyrifos, dimethoate, and trichlorfon. The extraction method was applied to analyze OPPs in environmental water using HPLC along with UV detection. The method has a wide linear range (100–15,000 ng L −1 ), good linearity ( r  > 0.999), and low detection limits (26–30 ng L −1 ). The enrichment factor is ~1,000. The recoveries (at spiked levels of 100, 1,000 and 10,000 ng L −1 ) are in the range of 88.5–96.7 %, and the relative standard deviations range from 2.4 % to 8.7 %. Figure Schematic illustration of the preparation of CTAB coated Fe 3 O 4 @TiO 2 and its application as SPE sorbent for enriching OPPs

A nanocomposite composed of graphene oxide and magnetite (Fe 3 O 4 ) was coated with the ionic liquid (IL) 1,3-didecyl-2-methylimidazolium chloride and used to capture and separate hemin from serum samples. The critical parameters affecting the extraction of analyte, such as pH, surfactant and adsorbent amounts, and desorption conditions were studied and optimized. Following magnetic separation and desorption with a 5:1 mixture of acetic acid and acetone, hemin (an iron porphyrin complex) was quantified by FAAS of iron. Under optimum conditions, the enrichment factor was 96. The calibration curve was linear in the 4.8 to 730 μg L −1 concentration range, the limit of detection was 3.0 μg L −1 , and the relative standard deviations (RSDs) for single-sorbent repeatability and sorbent-to-sorbent reproducibility were less than 3.9 % and 10.2 % ( n  = 5), respectively. The adsorbent displayed adsorption capacity as high as 200 mg g −1 , indicating IL-coated Fe 3 O 4 /GO to be a good sorbent for the adsorption of hemin. The method was validated by determining serum hemin in the presence of a large excess (480-fold) of Fe 3+ without considerable interference. The results compare well to those obtained with a commercial hemin assay kit. The results show that this method can be successfully applied to the enrichment and determination of hemin in acid digested serum samples of breast cancer patients. Graphical abstract Fe 3 O 4 /GO nanocomposites were coated with the ionic liquid 1,3-didecyl-2-methylimidazolium chloride and used as the sorbent for the separation and preconcentration of hemin from blood serum samples prior to determination using by flame AAS.

Magnetic nano-carbon core shell was applied as mixed hemimicelle magnetic solid phase extraction adsorbent to introduce a novel sample preparation method for determination of acrylamide from potato chips. Acrylamide is identified as neurotoxic, a probable human carcinogen (group 2A) compound. Effective extraction parameters such as type and amount of extracting solvent, type and amount of adsorbent, time of extraction and desorption, the effect of pH, time of ionic liquid loading on the adsorbent and stirring rate (rpm) were studied and optimized. Under optimized extraction conditions, a good linearity was observed in the concentration range of 100–1500 ng/g. Limit of detection was observed as 30 ng/g. Application of the proposed method was surveyed by analysis of some potato chips brands available in the local supermarkets. The satisfactory results with the recovery of 95.58% revealed that the proposed method could be applied in food analysis laboratories.

The co-adsorption of mixed nonionic surfactant and imidazolium-based ionic liquid, Triton X100 (TX100), with 1-cetyl-3-methylimidazolium bromide (C16mimBr) adsorbed onto the surface of magnetic halloysite nanotubes (MHNTs) was used as an efficient adsorbent for simultaneous determination of amlodipine and nimodipine in urine. The designed adsorbent was characterized by TEM, TGA, FTIR, and DLS analysis methods. All the parameters that influence the extraction efficiency are optimized with the aid of response surface methodology (RSM). The effects of nonionic surfactant TX100 with different structures of ionic-liquid-coated MHNTs were investigated. Under optimum conditions, extraction recoveries of amlodipine and nimodipine were in the range of 73.8–81.2 and 94.3–96.1%, with RSDs (n = 3) of 2.6–5.5% in spiked urine samples, respectively. The adsorption mechanism principal of mixed hemimicelles was discussed in this study. The limit of detection obtained for analytes was < 0.002 μg·mL−1. To our knowledge, this was the first attempt using a mixed hemimicelle solid-phase extraction (SPE) based on MHNTs and nonionic surfactant and imidazolium-based ionic liquid for the simultaneous determination of amlodipine and nimodipine in biological samples.

In the present study mixed hemimicelles dispersive solid phase extraction using polyaniline functionalized silica coated magnetic (Fe 3 O 4 @SiO 2 @PANI) nanoparticles for the extraction of chlorophenols from aqueous samples was investigated. The silica coated magnetic nanoparticles (Fe 3 O 4 @SiO 2 ) were synthesized, and then functionalized with aniline via oxidative polymerization reaction on the surface of silica coated magnetic nanoparticles (Fe 3 O 4 @SiO 2 @PANI). The obtained nanoparticles were characterized with scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transformed infrared spectrometry (FTIR) and N 2 adsorption/desorption methods. The synthesized Fe 3 O 4 @SiO 2 @PANI nanoparticles were applied as adsorbents for the extraction of chlorophenols (2-chlorophenol, 4-chlrorphenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol) and the factors affecting extraction efficiency were optimized. At optimum conditions, good linearity with correlation of determination (r 2 ) values ranges from 0.9931 to 0.9998, limits of detection in the range of 0.32–0.6 µg L −1 and recoveries of chlorophenols using the proposed method were obtained between 91.0 and 95.0%. The proposed method was applied successfully to the extraction of chlorophenols from different matrix of water samples.