Ultrasound-assisted dispersive solid phase extraction for promoting enrichment of ng L-1 level Hg2+ on ionic liquid coated magnetic materials

Facile fabrication of novel magnetic MOFs for highly efficient adsorption and determination of organophosphorus pesticides

The hazardous effects of residues from organophosphorus pesticides (OPPs) on human health have prompted researchers to look for innovative adsorbents and detecting techniques. Herein, a simple and economical material Fe3O4@PCN-224 was effectively produced as a desirable adsorbent for OPPs residues adsorption by integrating magnetic polydopamine (PDA) with the zirconium-based metal-organic framework (PCN-224). Modification of magnetic cores with PCN-224 allowed a dramatic increase in surface area and porosity to enhance pesticide adsorption. Moreover, the adsorption mechanisms inferred that π-π interactions, covalent bonds, and hydrogen bonds may promote the beneficial adsorption of OPPs by Fe3O4@PCN-224. Finally, the Fe3O4@PCN-224-based HPLC method exhibited with low detection limits (0.014-0.051 μg/L), good precision (1.70 % - 3.49 %), wide linearity (1-100 μg/L, R2 ≥ 0.9936), satisfactory recoveries (86.16 % - 106.45 %), and high enrichment factors (92-101), demonstrating its significant potential for efficient extraction, enrichment, and analysis of OPPs in complex matrix samples.

Rapid determination of Se(IV) and tSe in fungal samples by foam electrode-based electrolytic hydride generation coupled atomic fluorescence spectrometry

The key to accurately identifying trace heavy metal elements is to achieve efficient sample introduction while shielding the interference of matrix components. Taking the electrolytic hydride generation (EHG) technology as an example, this paper explored the effects of cathode materials and structural factors on the electrosynthesis of hydrogen selenide (H2Se), particularly on suppressing interference from coexisting components. Systematic electrochemical and spectroscopic tests show that the nickel-based electrode can promote the generation of H2Se, while the multi-layer foam structure with large specific surface area, rich pores and weak gas evolution effect improves the yield and stability of electrosynthesis reaction. Even if the surface state of the electrode changes due to the electrodeposition of high concentration interference ion, the electrochemical behavior of selenium (Se) is basically not affected. After coupling with an atomic fluorescence spectrometer detector, this method has a low detection limit (0.13 μg L-1), a wide linear range (2-100 μg L-1), and stable signal output (RSD, 3.3%, n = 11). With the assistance of high-frequency ultrasound sample extraction and pre-reduction measures, Se(IV) and total Se (tSe) in fungal samples such as mushrooms can be quickly quantified without pre-separation of the matrix. The contribution of this study is to provide an economical and sustainable electrochemical gas separation strategy for spectroscopic quantification of trace and even ultra-trace heavy metal elements in complex matrices.

High sensitivity atomic fluorescence spectroscopy for the detection of AsIII by selective electrolysis of arsenic on nanoflowers-like Fe/NFE

Modified electrosynthetic sample introduction technique is a reliable means of solving the problem of high sensitivity analysis of trace arsenite. This article attempts to achieve selective electroreduction of AsIII through the construction of electrode surfaces with different structures and materials from the perspective of interface reactions. Among the four transition metal modifiers, the iron modified nickel foam electrode with nano-flower structure documented higher efficiency in inducing arsenic reduction and better species selectivity. Systematic electrochemical and spectroscopic tests suggest that strong adsorption effect between Fe and AsIII, appropriate hydrogen evolution potential, and catalytic activity jointly promote efficient electroreduction of AsIII. Optimization based on electrode materials and electrolysis conditions, with high sensitivity, wide linear range (0.1-50 μg L-1), and excellent species selectivity, this paper offers an efficient and economic sample introduction method for trace AsIII/V selective atomic spectroscopy direct determination.

Ultrasonic assisted magnetic solid phase extraction of ultra-trace mercury with ionic liquid functionalized materials

Due to the agglomeration between particles, the inherent adsorption characteristics of magnetic powder materials are usually difficult to fully display. Taking ionic liquid functional materials as an example, the enrichment behavior of these adsorbents for trace mercury (Hg²⁺) in ultrasonic (US) assisted dispersion mode was systematically studied. The dissociation of protonic ionic liquids (IL) occur in the process of dispersion and the strong electrostatic attraction can improve the diffusion and adhesion of mercury on the adsorbent surface. Spectral measurement data showed that with the help of US, the more uniform dispersion of magnetic materials accelerated the adsorption of trace Hg²⁺. Ultrasonic intrinsic parameters such as frequency, power and radiation duration significantly affect the dispersion and apparent adsorption properties of magnetic functional materials. In the range of experimental parameters, the dye/paper image experimental results documents that there is a positive correlation between cavitation effect and ultrasonic frequency/power. The enrichment degree of fixed adsorbate (0.1 μg L^-1) under high frequency (59 kHz) or high-power input (100%) is 1-2 times higher than that under low frequency (40 kHz) or low power (60%) input. This is a valuable conclusion for the subsequent study of US dispersion of magnetic and even non-magnetic powder materials. In addition, the in-situ desorption and accurate measurement of adsorbed mercury were realized by combining slurry vapor generation atomic fluorescence spectroscopy (SVG-AFS). The constructed US assisted magnetic solid phase extraction (US-MSPE) method has the characteristics of low detection limit (0.36 ng L^-1), high recovery (>90%), sustainable utilization (>3) and reasonable measurement deviation (<5%), which can meet the requirements of ultra-trace Hg²⁺ (0.01-1.0 μg L^-1).

Design and Preparation of Imidazole Ionic Liquid-Based Magnetic Polymers and Its Adsorption on Sunset Yellow Dye

Magnetic polymers are often used as loading materials for ionic liquids because of their excellent magnetic separation properties. In this study, a novel imidazolium-based ionic liquid-modified magnetic polymer was synthesized by suspension polymerization and grafting, denoted as γ-Fe₂O₃@GMA@IM, and this magnetic polymer was used for the adsorption of the acid dye FCF. The magnetic polymer was characterized by SEM, FTIR, XRD, VSM and TGA. These techniques were used to reveal the overall physical properties of magnetic polymers, including the presence of morphology, functional groups, crystalline properties, magnetism and thermal stability. Studies have shown that γ-Fe₂O₃@GMA@IM can adsorb FCF in a wide pH range (2–10), with a maximum adsorption capacity of 445 mg/g. The adsorption data were more in line with the pseudo-second-order kinetic model and the Freundlich isotherm. In order to investigate its reusability, this study used 10% NaCl as the desorption solution, and carried out five batches of adsorption–desorption cycles. After five cycles, the adsorption effect was maintained at 98.3%, which showed a good recycling performance.

Preconcentration and determination of trace Hg(ii) using ultrasound-assisted dispersive solid phase microextraction

Defect rich molybdenum disulfide (MoS₂) nanosheets were hydrothermally synthesized and their potential for ultrasound assisted dispersive solid phase microextraction of trace Hg(ii) ions was assessed. Ultrasonic dispersion allows the MoS₂ nanosheets to chelate rapidly and evenly with Hg(ii) ions and results in improving the precision and minimizing the extraction time. The multiple defect rich surface was characterized by X-ray diffraction and high-resolution transmission electron microscopy. The surface charge of intrinsically sulfur rich MoS₂ nanosheets and their elemental composition was characterized by zeta potential measurements, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The cracks and holes on the basal planes of MoS₂ led to diffusion of the Hg(ii) ions into the interior channels. Inner-sphere chelation along with outer-sphere electrostatic interaction were the proposed mechanism for the Hg(ii) adsorption onto the MoS₂ surface. The experimental data showed good selectivity of MoS₂ nanosheets towards Hg(ii) adsorption. The systematic and constant errors of the proposed method were ruled out by the analysis of the Standard Reference Material (>95% recovery with <5% RSD). The Student's t-test values for the analyzed Standard Reference Material were found to be less than the critical Student's t value at 95% confidence level. The limit of detection (3S) was found to be 0.01 ng mL⁻¹. The MoS₂ nanosheets were successfully employed for the analysis of Hg(ii) in environmental water samples.

Hg(ii) ion adsorption onto an MoS₂ surface.