Quantification of trace heavy metals in environmental water, soil and atmospheric particulates with their bioaccessibility analysis.

In this work, sulfhydryl (SH) functionalized magnetic covalent organic framework (COF) was synthesized by using 4-aldehyde phenyl butadiyne (DEBD) and 1,3,5-tris(4-aminophenyl) benzene (TAPB) as the monomers and ethanedithiol as the modifier, with the aid of thiol-alkyne "click" reaction. The prepared Fe3O4@COFTAPB-DEBD@SH exhibited relatively strong magnetism (32.8 emu g-1), good stability and selectivity to target analytes with a high sulfhydryl content (0.24 mmol g-1). Based on Fe3O4@COFTAPB-DEBD@SH, a method combining magnetic solid phase extraction with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the quantitative analysis of trace metals. Under the optimal conditions, the method merited fast desorption kinetics (<2 min), adsorption kinetics (<20 min), fast phase separation (<1 min), high enrichment factor (100), and the detection limits for Cd, Hg, Pb and Bi were determined to be 1.18, 0.51, 4.91 and 0.39 ng L-1, respectively. A good resistance to complex matrices was demonstrated for the method in the analysis of soil, atmospheric particles and simulated pulmonary fluids samples. Certified reference materials (coal fly ash GBW08401 and soil GBW07427) were employed to validate the accuracy of the method. Four target metals in the range of 12.9-215 ng L-1, 0.06-24.6 µg g-1 and 0.52-33.1 ng m-3 were found in local water, soil and atmospheric particulates (PM), respectively. Additionally, artificial lysosome solution and gamble's solution were used to simulate human pulmonary fluid and the bioaccessibility of Cd, Hg, Pb and Bi in PM2.5 was evaluated to be 58.6-73.1 % and 1.3-7.1 %, respectively.

3D printed stir bar sorptive extraction coupled with high performance liquid chromatography for trace estrogens analysis in environmental water samples.

BACKGROUND: Any imaginary shape with good preparation reproducibility can be made by 3D printing technology, and it has been applied in various fields. Comparatively, its applications in sample pre-treatment are relatively less, most of which involves making extraction sorbents and producing non-functionalized devices for support assistance. 3D printing has not been applied to fabricate stir bars in stir bar sorptive extraction, mainly due to the lacking of suitable printing feedstocks. This work aimed to fabricate stir bars by 3D printing, reducing the manufacturing cost and steps and improving preparation reproducibility. (90) RESULTS: By using fused deposition modeling technique and porous filament printing feedstock, stir bars were fabricated without any modifications. Adsorption performance of 3D printed stir bars were investigated for substances with different structures and polarities. Five estrogens with adsorption efficiencies of over 80 % were selected as the representatives. The 3D printed stir bars exhibited good preparation reproducibility (2.9-4.4 %) and higher extraction recoveries (73-81 %) for five estrogens than commercial polydimethylsiloxane coated stir bars (13-69 %) in a shorter time (90 vs 120 min). They showed long lifespan (160 times) with good mechanical properties and merited reduced manufacturing cost (0.064 $ per bar) and manual operation. A method of stir bar sorptive extraction coupled with high performance liquid chromatography was proposed for trace analysis of estrogens in environmental water. Under the optimized conditions, the linear ranges for estrogens were 0.5-200 µg/L with LODs of 0.13-0.17 µg/L. (136) SIGNIFICANCE: The feasibility of fused deposition modeling in stir bar fabrication was demonstrated, along with the potential of porous filament printing feedstock as the sorbent for substances with medium polarity. 3D printed stir bars were featured with excellent preparation reproducibility, long lifespan, and good mechanical properties. The stir bar fabrication method can be used for mass production with minimal differences in products performance. (62).

Covalent organic framework-based magnetic solid phase extraction coupled with micellar electrokinetic chromatography for the analysis of trace organophosphorus pesticides in environmental water and atmospheric particulates.

A magnetic covalent organic framework material (M-COF) with conjugated structure, high surface area and good chemical stability, was prepared for the adsorption of nine organophosphorus pesticides (OPPs). The extraction recovery of the M-COF for nine target OPPs were 64-91%, and the extraction dynamics was relatively fast. Based on it, a method by combining magnetic solid phase extraction (MSPE) with sweeping micellar electrokinetic chromatography (MEKC) was developed for the determination of nine OPPs in environmental water and atmospheric particle samples. The enrichment factor (EF) of MSPE-sweeping-MEKC for nine target OPPs are 1740 and 3626 times, with the limits of detection of 0.78-2.33 µg L-1. This method was used to analyze nine OPPs in environmental samples, and the recovery of nine OPPs in spiked East Lake water, Triangle Lake water, the extracts of PM2.5, PM10 and TSP were 81.0-111%, 83.6-111%, 83.1-117%, 81.7-114% and 80.2-114%, respectively. The method is sensitive, rapid and simple, and can be used for the quantification of interest OPPs in environmental samples with complex matrix.

Amino functionalized magnetic covalent organic framework for magnetic solid-phase extraction of sulfonylurea herbicides in environmental samples from tobacco land.

An amino-functionalized magnetic covalent organic framework composite TpBD-(NH2 )2 @Fe3 O4 (Tp=Tp1,3,5-triformylphloroglucinol, BD-(NH2 )2 is 3,3',4,4'-biphenyltetramine) was prepared by post-synthesis modification. Due to its abundant benzene rings and amino groups, large specific surface area and porous structure, the prepared TpBD-(NH2 )2 @Fe3 O4 exhibits high extraction efficiency toward sulfonylurea herbicides. Based on this, a new method of magnetic solid-phase extraction with TpBD-(NH2 )2 @Fe3 O4 as the sorbent combined with high-performance liquid chromatography and ultraviolet detection was developed for trace analysis of sulfonylurea herbicides in environmental water, soil and tobacco leaves samples from tobacco land. Under the optimized conditions, the limits of detection within 0.05-0.14 µg/L were achieved with a high enrichment factor of 217-260-fold, and the relative standard deviations were 4.9-7.5% (n = 7, c = 0.5 µg/L). The linear range was around three orders of magnitude with the square of correlation coefficient higher than 0.9936. The method was applied to analyze five sulfonylurea herbicides in the environmental water, soil, and tobacco leave samples collected from tobacco land. No sulfonylurea herbicides were detected in these samples. The recoveries of target sulfonylurea herbicides in spiked environmental water, soil, and tobacco leaf samples were found in the range of 90.7-104, 70.7-99.0, and 59.3-97.8%, respectively. The results illustrate that the established TpBD-(NH2 )2 @Fe3 O4 -magnetic solid-phase extraction- high-performance liquid chromatography-ultraviolet detection method is efficient for the analysis of trace sulfonylurea herbicides in environmental samples.

Imine-linked covalent organic frameworks coated stir bar sorptive extraction of non-steroidal anti-inflammatory drugs from environmental water followed by high performance liquid chromatography-ultraviolet detection.

In this study, spherical imine-linked covalent organic frameworks (COFs) were fabricated from 2,5-dimethoxybenzene-1,4-dialdehyde (DMTP) and 1,3,5-tris (4-aminophenyl) benzene (TAPB) and named as TAPB-DMTP-COFs. The resulting powders were coated onto bare glass bars via physical-adhesion to obtain TAPB-DMTP-COFs coated stir bars. The self-made stir bars exhibited higher extraction efficiency (74-85%) and faster dynamics (50 min) towards non-steroidal anti-inflammatory drugs (NSAIDs) over ethylene glycol-Silicone (42-68%, 180 min) and polydimethylsiloxane (3-61%, 180 min) coated stir bars. Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), zeta potential and water contact angle were employed to provide a comprehensive understanding of the adsorption mechanism between the coating and analytes. The results displayed that methoxy group worked as an adsorption site helping the adsorption of interest NSAIDs onto the TAPB-DMTP-COFs coating and hydrogen bonds formed between the O atoms and the analytes. Additionally, the adsorption mechanisms possibly also involved π-π interaction and hydrophobic interaction. Moreover, TAPB-DMTP-COFs coated stir bars exhibited good stability and could be reused more than 60 times. Subsequently, a method by combining TAPB-DMTP-COFs coated stir bar sorptive extraction (SBSE) with liquid chromatography (HPLC)-ultraviolet detector (UV) was established for the determination of four NSAIDs in environmental waters. Under the optimized conditions, the established method showed a wide linear range of 0.2/1-500 µg/L for interest NSAIDs, the limits of detection varied from 0.039 to 0.312 µg/L. Yangtze River water, East Lake water and Spring water were subjected to the proposed method, the recoveries in spiked samples were 84.7-104%, 81.2-101% and 82.6-97.6%, respectively.

Chip-based array magnetic solid phase microextraction on-line coupled with inductively coupled plasma mass spectrometry for the determination of trace heavy metals in cells.

Determination of trace elements in cells is critical to metallomics research and still faces tremendous difficulties even with the help of highly sensitive inductively coupled plasma mass spectrometry (ICP-MS). Microfluidic chips offer a functional tool-set for cell analysis with features of miniaturization, integration and automation. In this work, we proposed a chip-based array magnetic solid phase microextraction (MSPME) system and on-line combined it with ICP-MS via microflow concentric nebulization for the determination of trace Cu, Zn, Cd, Hg, Pb and Bi in cells. Under the optimized conditions, the limits of detection of the developed on-line chip-based array MSPME-ICP-MS system are 49, 43, 4.2, 6.1, 13 and 18 ng L(-1) for Cu, Zn, Cd, Hg, Pb and Bi, respectively. The proposed method was applied to the analysis of target heavy metals in three kinds of cells (HepG2, Jurkat T and MCF7), and the recoveries for the spiked samples were in the range of 83.8%-117%. The extractable species of the target metals in cells were also studied and the results demonstrated a high selectivity of the developed methods towards free metal ions and/or their small molecular species.