Amine-functionalized MIL-53(Al)-coated stainless steel fiber for efficient solid-phase microextraction of synthetic musks and organochlorine pesticides in water samples

Superhydrophobic Nanosilica Decorated Electrospun Polyethylene Terephthalate Nanofibers for Headspace Solid Phase Microextraction of 16 Organochlorine Pesticides in Environmental Water Samples

A new solid phase micro extraction (SPME) fiber coating composed of electrospun polyethylene terephthalate (PET) nanofibrous mat doped with superhydrophobic nanosilica (SiO2) was coated on a stainless-steel wire without the need of a binder. The coating was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR) techniques and it was used in headspace-SPME of 16 organochlorine pesticides in water samples prior to gass chromatography micro electron capture detector (GC-µECD) analysis. The effects of main factors such as adsorption composition, electrospinning flow rate, salt concentration, extraction temperature, extraction time, and desorption conditions were investigated. Under the optimum conditions, the linear dynamic range (8−1000 ng L−1, R2 > 0.9907), limits of detection (3−80 ng L−1), limits of quantification (8−200 ng L−1), intra-day and inter-day precisions (at 400 and 1000 ng L−1, 1.7−13.8%), and fiber-to-fiber reproducibility (2.4−13.4%) were evaluated. The analysis of spiked tap, sewage, industrial, and mineral water samples for the determination of the analytes resulted in satisfactory relative recoveries (78−120%).

Efficient extraction of trace organochlorine pesticides from environmental samples by a polyacrylonitrile electrospun nanofiber membrane modified with covalent organic framework

Detecting and analyzing of the trace organochlorine pesticides (OCPs) in the real water has become a big challenge. In this work, a novel functional electrospun nanofiber membrane (PAN@COFs) was synthesized through the in situ growth of covalent organic frameworks (COFs) on a polyacrylonitrile electrospun nanofiber membranes under room temperature and used in the solid-phase micro-extraction (SPME) to enrich trace organochlorine pesticides (OCPs) in water. The resulted PAN@COFs composite consisted of numerous nanofibers coated ample porous COFs spheres (~ 500 nm) and owned stable crystal structure, abundant functional groups, good stability. In addition, the enrichment experiments clearly revealed that PAN@COFs exhibited rather outstanding performance on adsorbing the trace OCPs (as low as 10 ng L^-1) with the enrichment of 482-2686 times. Besides, PAN@COFs displayed good reusability and could be reused 100 times. Notably, in the real water samples (sea water and river water), the high enrichment factors and recovery rates strongly confirmed the feasibility of PAN@COFs for detecting the trace OCPs. Furthermore, due to the synergy of π-π stacking interaction and hydrophobic interaction between the OCPs molecules and PAN@COFs, the OCPs could be efficiently adsorbed on PAN@COFs, even under the extremely low driving force.

Utilization of montmorillonite nanocomposite incorporated with natural biopolymers and benzyl functionalized dicationic imidazolium based ionic liquid coated fiber for solid-phase microextraction of organochlorine pesticides prior to GC/MS and GC/ECD

A novel montmorillonite clay (MMT) bionanocomposite modified with chitosan (CH), carboxymethyl cellulose (CMC), and benzylimidazolium based dicationic ionic liquid with tetraethylene glycol linker (DIL) was fabricated on stainless steel wire by in situ process. The MMT-CH-CMC-DIL coated solid-phase microextraction (SPME) fiber was examined for the determination of organochlorine pesticides (OCPs) in real samples by HS-SPME-GC method using mass spectrometry (MS) and electron capture detector (ECD). Under optimized conditions, the proposed method exhibited low limits of detection (0.5 ng L^-1 with MS and 0.1 ng L^-1 with ECD detection), good linearities (R² = 0.9972-0.9993 with MS and 0.9987-0.9998 with ECD detection), favorable single-fiber repeatability, and fiber-to-fiber reproducibility (less than 8.2% and 9.9% for both types of detection) and high reusability around 125 cycles. Recovery studies were carried out for OCPs in tap water, green tea, and milk samples to verify the applicability of the developed SPME-GC method.

On the use of metal-organic frameworks for the extraction of organic compounds from environmental samples

The determination of trace metals and organic contaminants in environmental samples, such as water, air, soil, and sediment, is until today a challenging process for the analytical chemistry. Metal-organic frameworks (MOFs) are novel porous nanomaterials that are composed of metal ions and an organic connector. These materials are gaining more and more attention due to their superior characteristics, such as high surface area, tunable pore size, mechanical and thermal stability, luminosity, and charge transfer ability between metals and ligands. Among the various applications of MOFs are gas storage, separation, catalysis, and drug delivery. Recently, MOFs have been successfully introduced in the field of sample preparation for analytical chemistry and they have been used for sample pretreatment of various matrices. This review focuses on the applications of MOFs as novel adsorbents for the extraction of organic compounds from environmental samples.

Ketoenamine Covalent Organic Framework Coating for Efficient Solid-Phase Microextraction of Trace Organochlorine Pesticides

Fiber coating is a key part of solid-phase microextraction (SPME) technology, and it determines the selectivity, sensitivity, and reproducibility of the analytical method. A ketoenamine covalent organic framework called Tp-Azo-COF with rich electronegative N atoms was prepared as an SPME coating in this work. The Tp-Azo-COF coating had a large surface area of 1218 m² g^-1 and good thermal and chemical stability, and it was applied for the extraction of organochlorine pesticides (OCPs). According to quantum chemistry calculations, the adsorption affinity of the Tp-Azo-COF coating for five OCPs was primarily affected by the halogen bond and hydrophobicity interaction. The extraction efficiencies of the Tp-Azo-COF coating for five OCPs were higher than those of three commercial SPME fiber coatings, and the enrichment factors ranged from 1061 to 3693. When combined with gas chromatography-tandem mass spectrometry, a wide linear range (0.1-1000 ng L^-1), low limits of detection (0.002-0.08 ng L^-1), and good fiber-to-fiber accuracy (4.3-10.9%) were achieved under optimal conditions. Moreover, the applicability of the developed method was evaluated by analyzing four samples (milk, green tea, tap water, and well water), and the recoveries were in the range of 83.4-101.6%, with relative standard deviations <8.6%. This research extends the application of the stabilized ketoenamine COF as a sample enrichment probe for OCP analysis.

Zirconium(Ⅳ)-based metal-organic framework for determination of imidacloprid and thiamethoxam pesticides from fruits by UPLC-MS/MS

Zirconium(Ⅳ)-based metal-organic framework (MOF)-UiO-66-NH₂ was fabricated to adsorb the imidacloprid and thiamethoxam in fruit samples before analysis using UPLC-MS/MS. The UiO-66-NH₂ was confirmed by SEM, FTIR, and XRD. Key experimental parameters were investigated by response surface methodology (RSM). The desirability recovery of imidacloprid was 94.52% under optimum conditions (mount of adsorbent = 52.48 mg, volume of eluent = 5.18 mL, pH = 9, extraction time = 15 min). The desirability recovery of thiamethoxam was 93.57% under optimum conditions (mount of adsorbent = 50.58 mg, volume of eluent = 2.6 mL, pH = 5.65, extraction time = 11.94 min). Under the optimal conditions, the actual recovery of imidacloprid and thiamethoxam was 92.39% and 94.37%, respectively. Besides, the method was applied successfully to detect imidacloprid and thiamethoxam in different fruit samples. The results demonstrated that the UiO-66-NH₂ is an excellent adsorbent for the extraction imidacloprid and thiamethoxam from fruit samples.

Solid-phase microextraction using a β-ketoenamine-linked covalent organic framework coating for efficient enrichment of synthetic musks in water samples

Covalent organic frameworks with tunable porous crystallinity and outstanding stability have recently exhibited fascinating pretreatment performance as solid-phase microextraction coatings. In this report, a β-ketoenamine-linked covalent organic framework (TpPa-1) was successfully constructed through a Schiff-base-type reaction between 1,3,5-triformylphloroglucinol (Tp) and para-phenylenediamine (Pa-1). A TpPa-1 coating was then fabricated on a stainless-steel fiber for capturing trace synthetic musks. This TpPa-1 coating exhibited strong interaction with synthetic musks because of its hydrophobicity and π-π affinity. This TpPa-1-based solid-phase microextraction methodology, coupled with gas chromatography-tandem mass spectrometry, provided high enrichment factors (1214-12 487), wide linearity (0.5-1000 ng L-1), low limits of detection (0.04-0.31 ng L-1), and acceptable reproducibility (relative standard deviation, <10%) for nine synthetic musks. Recoveries at three spiked levels in three types of water samples were between 76.2% and 118.7%. These results indicated the promising applicability of the TpPa-1 as a solid-phase microextraction fiber coating for reliably detecting trace concentrations of synthetic musks in the environment.

Recent Applications and Newly Developed Strategies of Solid-Phase Microextraction in Contaminant Analysis: Through the Environment to Humans

The present review aims to describe the recent and most impactful applications in pollutant analysis using solid-phase microextraction (SPME) technology in environmental, food, and bio-clinical analysis. The covered papers were published in the last 5 years (2014–2019) thus providing the reader with information about the current state-of-the-art and the future potential directions of the research in pollutant monitoring using SPME. To this end, we revised the studies focused on the investigation of persistent organic pollutants (POPs), pesticides, and emerging pollutants (EPs) including personal care products (PPCPs), in different environmental, food, and bio-clinical matrices. We especially emphasized the role that SPME is having in contaminant surveys following the path that goes from the environment to humans passing through the food web. Besides, this review covers the last technological developments encompassing the use of novel extraction coatings (e.g., metal-organic frameworks, covalent organic frameworks, PDMS-overcoated fiber), geometries (e.g., Arrow-SPME, multiple monolithic fiber-SPME), approaches (e.g., vacuum and cold fiber SPME), and on-site devices. The applications of SPME hyphenated with ambient mass spectrometry have also been described.