Bis(trifluoromethanesulfonyl)imide-based ionic liquids grafted on graphene oxide-coated solid-phase microextraction fiber for extraction and enrichment of polycyclic aromatic hydrocarbons in potatoes and phthalate esters in food-wrap

Highly graphitized porous carbon/reduced graphene oxide for ultrahigh enrichment and ultrasensitive determination of polycyclic aromatic hydrocarbons

There is an urgent need to develop efficient and reliable coating materials for solid phase microextraction (SPME), in order to quantify and monitor pollutants in environmental waters. Herein, a highly graphitized porous carbon/reduced graphene oxide (PC/rGO) was successfully synthesized by pyrolysis of metal organic framework/graphene oxide precursors, and used as a SPME coating for ultrahigh enrichment of polycyclic aromatic hydrocarbons (PAHs) from water. The as-prepared PC/rGO exhibited high degree of graphitization, abundant number of micro/mesopores along with exceptional thermal stability, making it an ideal SPME coating material. The PC/rGO fiber offered an ultrahigh enrichment factor for PAHs (up to 126057), which could be attributed to the multiple interactions between the PC/rGO and PAHs, including hydrophobic and π-π interactions, partitioning, and mesopore filling effect. In the analysis of PAHs, the PC/rGO fiber showed a wide linearity (0.007-100 ng mL-1), low limits of detection (0.0005-0.005 ng mL-1), and good repeatability (RSDs <10.1%, n = 5) under optimized conditions. The established method was applicable for ultrasensitive determination of PAHs in different environmental waters and showed satisfactory recoveries. This study provides a novel way for constructing thermally stable SPME coating having efficient extraction performance.

Preparation and application of an imidazolium-based poly (ionic liquid) functionalized silica sorbent for solid-phase extraction of parabens from food samples

In this work, an imidazolium-based poly (ionic liquid) (poly(1-octyl-3-vinyl- imidazolium naphthalene sulfonate)) functionalized silica (poly(C8VIm+NapSO3-) @SiO2) was successfully prepared for the determination of parabens in food samples. The prepared poly(C8VIm+NapSO3-)@SiO2 was characterized by Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectrogram (XPS) and Scanning electron microscopy (SEM). The simulation calculation results indicated that the suitable binding energies were between the polymeric ionic liquids and parabens, and the main interactions for extraction were hydrogen bonding, electrostatic and π-π stacking interactions. In addition, compared with commercial extraction materials, the prepared poly(C8VIm+NapSO3-)@SiO2 sorbent showed comparable or even better extraction performance towards parabens. The effective parameters were optimized by a combination of the univariate method and Box-Behnken design (BBD). Under the optimum conditions, coupled with high performance liquid chromatography (HPLC), wide linear ranges (1.0-800 μg L-1), good linearity (R2 ≥ 0.9997) and low limits of detection (0.1 μg L-1) were obtained. In addition, the intra-day and inter-day relative standard deviations (RSDs) were all lower than 6.3%. Moreover, the proposed method was successfully used for the determination of parabens in food samples and satisfactory recoveries in the range of 76.9-97.4% were obtained. The results indicated that the proposed method had good sensitivity, accuracy and precision for the detection of parabens in food samples.

Covalent triazine-based frameworks for efficient solid-phase microextraction of phthalic acid esters from food-contacted plastics

Owing to various health threats associated with phthalic acid esters (PAEs), this category of endocrine-disrupting compounds has attracted more and more public scrutiny. However, the efficient preconcentration of PAEs from complex food-contacted plastics still remains challenging. Herein, three covalent triazine-based frameworks (CTFs) were constructed by facile Friedel-Crafts reactions of cyanuric chloride (CC), with triptycene (TPC), fluorene (FL) and 1,3,5-triphenylbenzene (TPB), respectively. Three CTFs were then employed as solid-phase microextraction (SPME) coatings for the extraction of PAEs. Benefiting from the large surface area and high pore volume, the newly-synthesized CC-TPC based SPME method exhibited large enrichment factors (978-2210), low limits of detection (0.027-0.10 ng g ^- 1), satisfactory linear ranges (0.09-20 ng g ^- 1), acceptable repeatabilities (4.3-9.6%) and high relative recoveries (92.0-104.6%).

New analytical strategies amplified with carbon-based nanomaterial for sensing food pollutants

The most significant topic currently under the moonlight is Nanobiotechnology and engineered nanomaterials. The novel characteristics displayed by engineered Nanomaterials, especially carbon-based nanomaterials, have spurred interest in its potential application in the food industry. It has provided opportunities for finding solutions to the long-standing challenges in the food industry to assess food safety, maintain food quality, extend the shelf life of produce, and efficiently deliver nutrients. Nanomaterials can be incorporated in food sensors facilitating efficient monitoring of crop maturity and detecting biological and chemical contaminants. When integrated into food packages, nanomaterials could aid in assessing the freshness and improving the quality of packaged foods. In addition, more efficient delivery of nutrients could be possible in foods fortified using nano compounds. The initial section of this review gives an overview of the broad application of nanotechnology in the food industry and carbon-based nanomaterials. The latter part focuses on nanotechnology in biosensors for food safety and quality monitoring.

Chitosan and dicationic ionic liquid intercalated clay-coated solid-phase microextraction fiber for determination of sixteen polycyclic aromatic hydrocarbons in coffee and tea samples

In the present study, solid-phase microextraction (SPME) fiber was prepared by coating clay (MMT)-chitosan (CH) and dicationic ionic liquid (DIL) onto the stainless-steel wire step by step. The characterization of fibers was performed by Fourier transform infrared spectroscopy, thermal analysis, x-ray diffraction analysis, and scanning electron microscopy. The prepared fibers were evaluated for separation and determination of 16 polycyclic aromatic hydrocarbons (PAHs) in coffee and tea samples in headspace- and direct immersion-SPME by coupling with gas chromatography/mass spectrometry. The analytical performance of MMT/CH/DIL fibers was carried out for the extraction of PAHs and compared with the performance of carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/CAR/PDMS (DVB/CAR/PDMS) fibers under optimized conditions. The wider linear ranges between 0.001 and 25 μg L^-1 with a coefficient of determination above 0.9962, low limits of detection between 0.0001 and 0.05 μg L^-1 and good intra-day repeatability from 2.45 to 6.48 % and fiber-to-fiber reproducibility from 3.19 % to 8.82 % were obtained for all PAHs in both methods with MMT/CH/octyl (O)-DIL fiber. The extraction recoveries of coffee and tea samples ranged from 87.5 to 112 % using the MMT/CH/O-DIL fiber in both SPME methods.

Magnetic covalent organic framework nanocomposites as a new adsorbent for the determination of polycyclic aromatic hydrocarbons in water and food samples

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.

Poly(ionic liquid)-hybridized silica aerogel for solid-phase microextraction of polycyclic aromatic hydrocarbons prior to gas chromatography-flame ionization detection

Using poly(ionic liquid) (PIL) and tetraethyl orthosilicate (TEOS) as the co-precursors, PIL-hybridized silica aerogel was prepared via sol-gel method for solid-phase microextraction (SPME). The ratio between PIL and TEOS was regulated to achieve the best extraction effect. The aerogel was coated onto the surface of stainless steel wire to get SPME fiber. Coupled to gas chromatography-flame ionization detector (GC-FID), the fiber was separately evaluated by the determination of alkanes, polycyclic aromatic hydrocarbons (PAHs), as well as BTEX (benzene, toluene, ethylbenzene, and xylenes) in immersion mode. The extraction performance of PAHs was attributed to π stacking and hydrophobic effect. After optimization of main extraction and desorption conditions, the SPME-GC-FID method was established towards eight PAHs, and it provided low detection limits (0.005 μg L^-1, 0.010 μg L^-1) and wide linear ranges (0.016-20.00 μg L^-1, 0.033-20.00 μg L^-1) with good linear coefficients (0.9991-0.9998). The method was applied to detect trace PAHs in real water samples, with relative recoveries of 86.2-119.2%. Furthermore, PIL-hybridized silica aerogel exhibits some superiorities like higher sensitivity, shorter extraction time, and better repeatability over other extraction coatings. The present work not only extends the range of aerogel materials but also promoted their further applications in sample preparation. Graphical abstract.

Construction of hypercrosslinked polymers for high-performance solid phase microextraction of phthalate esters from water samples

Design and synthesis of novel coatings for solid phase microextraction (SPME) is urgently needed for sample pretreatment. In this study, three hypercrosslinked polymers (HCPs) were constructed by the facile Friedel-Crafts alkylation reactions between tetraphenylethylene (TPE) and 1,4-bis(chloromethyl)benzene (BCMB), 4,4'-bis(chloromethyl)-1,1'-biphenyl (BCMBP), and cyanuric chloride (CC), respectively. The newly-synthesized HCPs were employed as SPME coatings for the extraction of phthalate esters (PAEs). Various parameters influencing the SPME efficiencies, including extraction time and temperature, ionic strength, stirring rate, desorption temperature and time were optimized. Under the optimal conditions, low limits of detection (0.003-0.033 μg L ^- 1), wide linearity (0.01-10 μg L ^- 1) and good repeatability (4.1-9.3%) were achieved. The HCPs-based SPME method was successfully applied for the determination of eight PAEs in environmental water and bottled water samples with recoveries from 75.3% to 116%. This method provides a good alternative for monitoring trace level of PAEs in water samples.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

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.

Recent applications of carbonaceous nanosorbents for the analysis of mycotoxins in food by liquid chromatography: a short review

Carbonaceous nanomaterials (multi-walled carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO)) have attracted attention over the last decade as adsorbents suitable for the analysis of organic and inorganic pollutants. In the present paper we review methods of mycotoxin analysis that involve sample extraction with carbonaceous nanosorbents, reported from 2011 onwards. Recent studies have highlighted the advantages of magnetically modified MWCNTs and GO in mycotoxin analysis, which may enable sample isolation through magnetic separation, reduce the interaction of nanoparticles, and enhance the recovery of analytes. The papers covered in this review point to promising applications of functionalised carbonaceous nanosorbents in mycotoxin analysis. While GO based sorbents can be effective for the adsorption of relatively polar aflatoxins, MWCNTs with high specific surface area and reduced agglomeration achieved through modification with silica and magnetic particles are preferred for the extraction of less polar mycotoxins.

Green construction of Fe3O4@GC submicrocubes for highly sensitive magnetic dispersive solid-phase extraction of five phthalate esters in beverages and plastic bottles

A well-designed core-shelled Fe₃O₄@graphitic carbon (Fe₃O₄@GC) submicrocube was in situ constructed in a simple, relatively green and eco-friendly ways basing on one-step pyrolysis of low-cost waste napkins-coated Fe₂O₃ submicrocubes. The Fe₃O₄@GC submicrocubes showed unique architectures where in situ generated thin graphitic carbon layer wrapped on the surface of Fe₃O₄, resulting in excellent affinity to five phthalate esters (PAEs), good reusability and rapid magnetic separation, therefore were employed as magnetic dispersive solid-phase extraction material combined with HPLC to simultaneously detect five trace PAEs in beverages and plastic bottles. Under optimized conditions, recoveries (80.0%-112.8%), precision (RSDs ≤ 8.8%), and limits of detection (LODs) for beverages (0.09-0.28 μg L^-1) and plastic bottles (0.01-0.03 μg g^-1) were obtained. This work not only establishes an effective method for simultaneous determination of five PAEs, but also opens up a new strategy to design/construct magnetic graphitic carbon-encapsulated core-shell materials using low-cost/recyclable napkins as carbon source.

An organic-inorganic hybrid silica aerogel prepared by co-precursor method for solid-phase microextraction coating

In order to improve the extraction performance of silica aerogel, an organic-inorganic hybrid silica aerogel was developed as the coating of solid-phase microextraction (SPME). It was prepared via the co-precursor reaction between tris(triethoxysilylpropyl)amine and tetraethyl orthosilicate. Coupled with gas chromatography, the hybrid silica aerogel-coated SPME fiber was evaluated using polycyclic aromatic hydrocarbons (PAHs). Compared to silica aerogel, the hybrid silica aerogel displayed better extraction performance, peak areas of PAH analytes were increased by about 2 times. The affecting parameters including extraction time, extraction temperature, ionic strength, stirring rate and desorption time were optimized, and an analytical method was established with wide linear ranges (0.005-20 μg L^-1, 0.010-20 μg L^-1, 0.100-20 μg L^-1), good correlation coefficients (0.9967-0.9994), low limits of detection (0.001-0.030 μg L^-1) and limits of quantitation (0.005-0.100 μg L^-1). Satisfactory extraction repeatability (RSD≤6.1%, n = 3) and preparation repeatability (RSD ≤ 9.8%, n = 3) were also obtained. Compared to the reported coatings and the commercial coating, the organic-inorganic hybrid silica aerogel has higher or comparable sensitivity, better repeatability, and shorter extraction time and longer service life. The established method was used for the detection of lake water and rain water, and some targets were quantified successfully.

Ionic liquid-functionalized graphene quantum dot-bonded silica as multi-mode HPLC stationary phase with enhanced selectivity for acid compounds

A novel IL/GQD/SiO₂ stationary phase for reversed-phase/normal-phase/ionic exchange and hydrophilic interaction liquid chromatography.